J PL Quarterly
Technical Review
Volume 1 July 1971 Number 2
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JPl QiiortPriy Ti;chn:c<>' H<'\.i("w
Volume 1, Number 2
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JPL Quarterly
Technical Review
Volume 1 July 1971 Number 2
Contents
1 A Comparison Between Planar and Nonplanar Free-Flight Data
P. Jaffe
9 Aerodynamics of Vehicles in Tubes
D. W. Kurtz
17 Aerobraking of High-Speed Ground Transportation Vehicles
W. Marko
23 Nitric Oxide Emission Studies of Internal Combustion Engines
F. H. Shairand J. H. Rupe
36 An All-Carbon Radiating Nozzle for Long-Burning Solid
Propellant Motors
R. L. Bailey and J. I. Shafer
47 Mariner Mars 1971 Orbiter Propulsion Subsystem Type
Approval Test Program
J. F. Stocky
54 Prediction of Lipid Uptake by Prosthetic Heart Valve Poppets
From Solubility Parameters
J. Moacanin, D. D. Lawson, H. P. Chin, E. C. Harrison,
and D. H. Blankenhorn
61 Resequencing of the Structural Stiffness Matrix to Improve
Computational Efficiency
R. Levy
71 On the Statistical Distribution of Spacecraft iVIaximum
Structural Response
J.-N. Yang
80 Use of Pulsar Signals As Clocks
P. Reichley, G. Downs, and G. Morris
87 Characteristics of a Cigar Antenna
S. A. Brunstein and R. F. Thomas
96 Improvements in Deep-Space Tracking by Use of
Third-Order Loops
R. C. Tausworthe
107 Non-orthogonal Redundant Configurations of Single-Axis
Strapped-Down Gyros
A. K. Bejczy
119 Analytically Determined Response of a 300-/^m Silicon
Detector to a Polyenergetic Beam of Neutrons
M. Taherzadeh
131 Remote Examination of Rock Specimens
J. D. Burke, R. Choate, and R. B. Coryell
Bibliography of Current Reporting
146 Author Index With Abstracts
243 Subject Index
264 Publication Index
JPL Quarterly Technical Review Volume 1, Number 2 July 1971
A Comparison Between Planar and Nonplaiiar
Free-Flight Data
p. Jaffe
Environmental Sciences Division
Results from the first program designed to explore the difference between
the planar and nonplanar dynamic stability coefficient, using tlie JPL
developed bi-planar wind-tunnel free-flight system, are presented. Two
widely different configurations, a blunt 60-deg half-angle cone and a sharp
10-deg half-angle cone were tested. The overall accuracy of the data was
extremely high and firmly demonstrates the capability of die technique.
Although no dramatic difference in the coefficients was apparent from the
data, which was limited in number, they do suggest that there is a favorable
increase in the coefficient as the motion becomes more nonplanar.
Introduction
Predicting the angle-of-attack history of a body exhibiting nonplanar
motion from planar data can be erroneous since it presupposes that there
are no aerodynamic coupling forces and further requires that the con-
ventional aerodynamic forces which are observable in the planar mode
are the same in the nonplanar mode. The investigation of this last require-
ment vs^as the main purpose of an experimental program conducted in
the JPL Supersonic Wind Tunnel using a refined nonplanar free-flight
system. Specifically, the program was directed toward the question of
whether the dynamic stability coefficient is different in the two modes.
For this investigation two widely different configurations were chosen:
a short, blunt 60-deg half-angle cone and a sharp 10-deg half-angle cone.
This article presents the results of this test program.
Test Operation
The basis of the testing technique is to launch models upstream into
the oncoming flow with a pneumatic gun (Reference 1). In the case of
nonplanar flight, the models are released with an initial angle of attack,
yaw angular velocity, and spin rate. The proper combination of these
three initial conditions will produce any desired nonplanar motion. The
motion is recorded with a high-speed 35-min movie camera operating
at about 2000 frames per second. Two views of the model in flight are
obtained by splitting the schHeren strobe light and directing the two
beam halves through the test section, 60 deg apart, by means of a complex
minor system (References 2 and 3). Generally, about 250 frames of data
are obtained for a flight. Each pair of angles from a frame set is measured
and mathematically transformed to a vertical and horizontal set. Nominal
accuracies are 0.2 deg for the slender models and 0.5 deg for the blunt
bodies. In addition to this data, an independent measurement of the
model's spin rate is obtained by means of either a fiber optics lens system
mounted inside the tunnel, which transmits a picture of the model's
base to an outside camera, or a stripe painted on the model.
The data is processed in a manner similar to the procedure used in
a ballistic range, which is to numerically fit the angle data with the
tricylic equation of motion (Reference 4). From this fit the static stability
coefficient (C-mJ, the dynamic stability coefficient (C,„, + C,„j), and the
magnus moment coefficient (Cmp) are obtained. The drag coefficient
(C/j) is independently obtained from the model's translational history.
The 60-deg blunt body test was conducted principally at Mach 3.97
with a few shots at Mach 1.65. The 10-deg cone test was performed at
Macli 4.56. The diameters of the blunt models and of the sharp cones
were 3.81 and 2.54 cm (1.5 and 1.0 in.), respectively. The models were
designed to optimize the number of pitch cycles and angle-of-attack
decay during a flight. This is accomplished by constructing them with a
dense core and a light plastic exterior shell; in the case of the blunt cones,
gold was used for the cores. Typical weights for the models were 28 g
for the 60-deg cones and 10 g for the 10-deg cones. The blunt cones
were launched at spin rates varying from zero to 35 rev/s. The 10-deg
cone spin rates v/ere from 90 to 135 rev/s (resonance was about 60 rev/s).
A representative a-fi plot (angle of attack versus angle of yaw) from
both tests is shown in Figures 1 and 2 along with a frame of movie data
from each flight. The stars are the raw data points obtained from the
movie frames and the smooth curves are from the fit equations. The
standard rms angle-of-attack deviations were about 0.4 deg for the 10-deg
cone flights and 0.9 deg for the blunt body flights.
Test Results
Before proceeding to the dynamic stability data, it is wise to first
investigate the drag and static stability results since they provide a gage
as to the quality of the data. The drag and static stability coefficients
are the results of first-order driving forces and can be obtained much
more accurately than the dynamic stability coefficient which is the result
of second-order forces. If the static data from a flight looks good, con-
fidence in the value of the dynamic stability coefficient is increased.
10
...
RUN 10/659;;;
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::::::::
;
.. ,11.
» ::
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:. : : :::..::
:::: :::(:::
:: -.! :: ::: :::s :
:: :: \- ::: :::: ;
:: :: :: ;:: :::: s,
':': \i w :■; ;;;; ;
. . . .\
;: :::
s -■-
\k \
m
:: :^::
:: ::: ::
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:
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; ■■■
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: - :
— -
::::
Ifftmtn
\ ;;;;;;::;:;:;:;;:;;;;;:
:;:
IB
[:: ::::::
::: :
I T .
nTTT
;:::::;;;:;;;
,,
; ;
-25 -20 -15 -10
-5
20 25
Figure 1. Representative 10-deg cone data
Figure 2. Representative 50-deg blunt body data
The drag and stability data are best correlated with the mean-square
resultant angle of attack, S-, which is defined as
s-
(tj-) dx
where t] is the resultant angle of attack and x is the relative distance
between the model and free-stream. It has been shown that if a body
has local drag coefficient of the form Co = Cd„ + k-q-, then the effective
drag coefficient is Cb^,,. = Cc^ + fcS-. Figure 3 contains the effective
drag data from both tests. The data consistency for both configurations
is excellent, particularly the 10-deg cone where the deviation is less than
0.25%. The data also exhibit straight-line correlations with 8-, which
means that the drag coefficients for both configurations are quadratic
functions of the angle of attack.
0.4
1 1
1
jy (a) 10-deg CONE
0.3
- ^--''''^
Re^K 0.34 X lO"^
M= 4.56
—
0.2
- ^..-O-^^^""^
-
0,1^
ri^—- — PLANAR TEST (REFERENCE 5)
1 1
1 1
1.50
1 1
1 1 1
1
1
1 1 1
1.45
-
0.5%
±
(b)
60-deg BLUNT BODY
Re^ K 0.086 X 10* _
M = 3.97
1.40
-
^
1.35
-
^^-tP -
1 30
1 1
1 1 1
1
1
1 1 1
40
60
100
Sl deg'
140 160 180 200 220
Figure 3. Drag results
Figure 4 contains the static stability data from both tests as a function
of S'. The 10-deg cone data does not vary with 8-, indicating that the
pitching moment is dependent upon the angle of attack (at least through
the region tested). The data deviation from the mean is excellent, less
than 0.5%. The blunt body data shows a large increase in the static
stability coefficient at large 8-'s, indicating a highly nonlinear pitching
moment. From an examination of the flights themselves, it appears that
the coefficients are more accurate than the scatter on the plot would
indicate. Fart of the problem is due to the use of 8" as the correlator
since it is not necessarily the proper one for a nonlinear pitching moment.
A vehicle experiencing the same 8- during both planar and circular flights
0.72
0.70
0.63
0.66
a) lO-deg CONE i
O— O A ""
f 0.5%'-
-O-
c.g./i! = 0.549
M = 4.56
100
0.13
0.12
1
(b) 60-deg
1 1 1 1 1
BLUNT BODY
' ' '^%-
—
-^ c.g./d = 0.19
~
1 1 1 1 1
Rej =0.086x10*
M = 3.97
1 1 1 1
20 40 60 80 100 120 140 160 180 200 220
S , deg
Figure 4. Static stability results
will not necessarily have the same effective static stabiHty coefficients
for both of them. This has been demonstrated for the case of a cubic
pitching moment (Cm = Ca + ko?), where the appropriate correlator for
an. arbitrary nonplanar flight is a much more complicated function than
8- (Reference 4). Another factor that might relate to the scatter of the
data is the "phase difference"; i.e., there appears to be a difference
between the time the amplitude nodes generated by the fit equation
occur and those formed by the raw data occur. (See Run 22, Figure 2,
for an example.) After extensive study of this problem, it is now believed
to be primarily the result of the combination of a highly nonlinear
pitching moment and a trim angle due to an offset center of gravity (c. g.).
Fortunately, both the correlator problem and the phase problem have
a rather small influence on the values of the aerodynamic coefficients
obtained from the data reduction, and although the scatter of the data
is larger than it should be, it is still quite small. Nevertheless, efforts to
reconcile the differences are continuing.
The dynamic stability data for both configurations are presented as
a function of S- in Figure 5 and as a function of roll rate to velocity ratio
(p/V) in Figure 6. This last parameter relates to the degree to which
the motion is nonplanar and is merely a first attempt to use a nonplanar
correlation parameter. When presented as a function of 8- (Figure 5),
particularly in the case of the blunt body, the data does not correlate
well. However, presented as a function of p/V, the correlation for both
configurations is substantially improved. Interestingly, both sets of data
for two completely different configurations demonstrate the same trend of
an increase in the dynamic stability (a more negative dynamic stability
coefficient is favorable) as the roll rate is increased to a point, and then
3.0
1
(a) 10-deg CONE
= -Q Q 0---
'
1 1
c.g./« =0.549
2.0
-___.
--• o-
Re^ =0.34X10'' -
1 .0
o
M = 4.56
•a
E
1
1
1 1
0.3-
0.2-
1 1 1 1 1
(b) 60-deg BLUNT BODY
III!
c.g./d = 0.19
CO q.
Rej =0.086X10*
o
M = 3.97
OOOo
°0 -
o
1 1 1 1 1
1 i 1 1
20 40 60 80 100 120 140 160 18
8 , deg
200 220
Figure 5. Dynamic stability data as a function of the mean-square
resultant angle of attack
d eg/ft
4 8 12 16 20
24
28
32 36 40
3.U
2.0
I
I.O
n
1 1 1 1 1
(a) 10-deg CONE
^PLANAR TEST (REFERENCE 5)
1 1 1 1
1
1
1
1
1 1 ' 1
o.g./i = 0.549
Re, = 0.34 X 10
d ~
M = 4.56
1 1 1
15 30 45 60 75 90 105 120 135
deg/m
deg/ft
0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 4.0
.D- 0.4
0.3
i I I I I r
(b) 60-deg BLUNT BODY
O Oo
o
o
o.ip
p
0.1
o
o o~
:.g./d = 0.19
M= 3.97
10
12
p/V, deg/m
Figure 6. Dynamic stability data as a function of the roil
to velocity ratio
a decrease in the dynamic stability. The fact that the dynamic stability
coefBcient changes with roll means that it is dependent upon the type
of motion the body is undergoing, which is contrary to the traditional
supposition that it is only dependent upon the angle of attack. It should
be mentioned, however, that in order to investigate this subject
thoroughly and obtain definitive conclusions much more data is required.
More work oriented toward defining the key parameters, which determine
dynamic stability, is needed.
References
1. Dayman, B., Jr., Free-Flight Testing in High-Speed Wind Tunnels,
AGARDograph 113. Advisory Group for Aerospace Research and
Development, North Atlantic Treaty Organization, Paris, May 1966.
2. Prislin, R. H., and Holway, H. P., "A Wind Tunnel Free-Flight Testing
Technique for Nonplanar Motion of Spinning Models," AIAA Paper
66-774, Sept. 1966.
3. Jaffe, P., "Planetary Entry Flight Dynamic Research," in Supporting
Research and Advanced Development, Space Programs Summary
37-62, Vol, III, pp. 218-222. Jet Propulsion Laboratory, Pasadena,
Calif., Apr. 30, 1970.
4. Murphy, C. H., Free-Flight Motion of Symmetric Missiles, BRL Report
1216. Ballistic Research Laboratory, Aberdeen Proving Ground, Md,
July 1963.
5. Jaffe, P., and PrisKn, R. H., Effect of Boundary-Layer Transition on
Dynamic Stability, Technical Report 32-841. Jet Propulsion Laboratory,
Pasadena, Calif., Mar. 1, 1966. (Reprinted from /. Spacecraft Rockets,
Vol. 3, No, 1, pp. 46-52, Jan. 1966.)
JPL Quarterly Technical Review Volume 1, Number 2 July 1971
Aerodynamics of Vehicles in Tubes
D. W. Kurtz
Environmental Sciences Division
Currently many transportation systems are being studied which require
vehicles to operate in tunnels under conditions of high blockage. As a con-
sequence, a great deal of interest is being generated in the aerodynamic
characteristics of such transportation systems. Model testing should be per-
formed to better understand the aerodynamic aspects of such systems. This
article presents a brief description of a facility that was constructed to study
these systems and some of the initial results which have been obtained to
date.
Introduction
Currently many transportation systems are being studied which require
vehicles to operate in tunnels (tubes) under conditions of high blockage
(vehicle frontal area occupying a significant portion of the tunnel cross-
sectional area). When this condition exists, the vehicle drag can be one
to two orders of magnitude greater than the value in free air. In addition,
the air velocities in the tunnel ahead of and behind the vehicle can be
an appreciable ratio of the vehicle velocity. A proper understanding of
these aerodynamic characteristics is necessary in order to efficiently
design systems utilizing vehicles in tunnels, which in turn will make it
possible to choose an optimum transportation system. In conjunction with
theoretical studies by the Aeronautics Department at the California
Institute of Technology, an experimental program was initiated at JPL
on the aerodynamics of vehicles traveling in tubes.
Facility
Currently operational is a 21.5-m (70-ft)^ long, 5.3-cm (2-in.) diameter,
vertically oriented aluminum tube that utilizes gravity to propel the test
1 Values in customary units are included in parentheses after values in SI (Inter-
national System) units if the customary units were used in the measurements or
calculations.
'JTILIiY
TUlr
il:t
:rCriON
Figure 1. Installation of VICS-70 facility
models. This facility, referred to as VICS-70 (vehicles in constrained
spaces), and two typical models are shown in Figure 1.
The 21.5-m (70-ft) tube replaces an original 9.8-m (32-ft) long, 5.3-cm
(2-iii.) diameter, vertically oriented Plexiglas tube that was used to
develoj) the necessary testing techniques for the more advanced, high-
precision facility now in operation. The 21.5-m (70-ft) tube is instru-
mented along its length with magnetic-coil pickups which are triggered
when magnets in the model pass each station and indicate model position
along the tube as a function of time. This configuration yields data from
which model velocity, acceleration, and drag can be determined. Wall
pressure ports are provided for recording the pressure history along the
10
SEPARATE HERE
TO CONVERT
TO 15.3-m
{50-ft) TUBE-
VENT TUBE (TYPICAL)
0.019-m IDx 0.254 r
{3/4-in. IDX lOin.)-
MAGNETIC COILS
(TYPICAL) -
INSTRUMENTATION
SECTION ■
Figure 2. Schematic of VICS-70 facility
tube. The tube is aligned to within ±0.4 mm (±0.015 in.) over the
21.5-m (70-ft) length. A schematic of the tube is shown in Figure 2.
The present facility is a very versatile one; several geometiic char-
acteristics of the 21.5-m (70-ft) tube are readily alterable. The tube length
can be decreased to 15.3 m (50 ft) or effectively increased up to an infinite
length by placing restrictions or orifices at the exit. Tube lengths shorter
than 15.3 m (50 ft) require that sections of the tube be removed, and
hence necessitate tube realignment upon their replacement. Venting
ports are provided along the entire length of the tube. The interior walls
of the tube are aerodynamically smooth but controlled roughness of
the walls can be introduced. It can be pressurized up to 1.03 X 10"
N/m^ (150 psi) and can use different fluids to obtain data through a wide
range of Reynolds numbers. A model launcher is used, when testing at
atmospheric pressure, to vary the initial velocity of the test models up
to 15 m/s (50 ft/s). Also, the flow velocity in the tube at the time of model
launch can be controlled in order that equihbrimn test conditions can
be obtained as soon as possible. To date, only circular cross-section models
equipped with fine Teflon centering skids have been tested. The effects
of model eccentricity in the tube and several models traveling simul-
taneously in the tube can be investigated.
11
Experimental Results
Drag
The effects o£ tube length and model blockage on the drag coeiBcient
of the models tested are appreciable. Test section length effects are
presented for three blockage ratios in Figure 3. (See Table 1 for definitions
of symbols used.) It should be pointed out, however, that some Reynolds
number effects are superimposed. Here, the drag coefficient is based on
the model velocity relative to the test section wall. The drag coeiBcient in
free air is about 0.5. Model length effects are important but to a lesser
degree. This effect is not nearly as strong for higher blockage models
and diminishes as models become very long. Nose and tail shapes exhibit
distinct, although minor, effects on the drag coefficient. Streamlined nose
<
AIR AT ATMOSPHERIC PRESSURE
STEADY STATE
i/d = 15
ELLIPSOIDAL NOSE
BLUNT BASE
/
-7^
/
/
/
~cr TS'
0--0— ■
.■0--
O a- = 0.50
A a- = 0.74
D cj- = 0. 90
10 10
TUBE LENGTH L/D
Figure 3. Variation of drag coefficient with tube length for three blockage ratios
12
Table 1. Nomenclature
a model cross-sectional area, m-
d model diameter, m
Ca^ drag coefficient based on the model velocity relative to the tube,
Ct,^ = drag / — pv-a
L/D ratio of tube length to tube diameter
i/d ratio of model length to model diameter
Ret^^ Reynolds number based on the model velocity and model diameter,
Rei^ = pvd/ij.
V model velocity relative to the tube, m/s
fi viscosity of test gas, N-s/m^
p density of test gas, kg/m^
a ratio of model cross-sectional area to tube cross-sectional area ( some-
times expressed in percent)
and tail sections resulted in about a 10% drag reduction on models with
a blockage ratio of 0.5 but little or no reduction on models with a. 0.9
blockage ratio.
The average velocity of the flow ahead of (and behind) the model
increases with the blockage ratio and decreases with the tunnel length.
The drag which the model experiences is a direct result of this since it
must move (or attempt to move) part of this column of air surrounding it.
The drag coefficient is quite sensitive to test Reynolds number in the
lower Reynolds number region (Figure 4). However, the drag coefficient
becomes much less sensitive at Reynolds numbers that are near full-scale
conditions.
Pressure Signature of Mode! Traveling in Tube
Experimental investigations performed to date on tube-vehicle systems
indicate that the near-field flow is quite complex even for the ideal
case; i.e., steady-state, incompressible-flow conditions. The characteristics
of the near-field flow (flow extending from just ahead of the model to
just aft of the model) can, in part, be inferred from the pressure distribu-
tion along the tube as the model passes. The experimental data show the
near-field flow to consist of many clearly distinct regions. As few as four
and as many as seven of these regions have been observed in each model
pressure signature. A sample of a pressure signature at the test section
wall in the vicinity of a 50% blockage model traveling at its equilibrium
13
10
STEADY STATE
L/D = CO
i/d = 15
SYMBOL GAS
OPEN AIR
^^
FLAGGED N^
TBI-
~*~ SHADED Frl2
o- = 0.50
O °- = 0.71
A c- = 0.74
D Cf = 0.90
A
■<^^-^^-4
~0----c&-_
"~-«- —
1 1
FULL-SCALE REYNOLDS NUMBER = 7.4 X lo'
WHERE:
TRAIN DIAM = 3.66 m (12 ft)
TUNNEL DIAM = 4.88 m (16 ft)
o- = 0.56
TRAIN VELOCITY = 30.48 m/s (lOOft/s)
1 1
10 10
REYNOLDS NUMBER Re ,
10"
Figure 4. Variation of drag coefficient with Reynolds number for
three blockage ratios
velocity is presented in Figure 5. Although recorded on a time scale,
the figure has been converted to a pressure distribution along the test
section in order to indicate the relative position of the model. Regions 1
and 6 indicate the pressure gradient in the test section due to the flow
ahead and behind the model, respectively. Region 1 is essentially pure
pipe flow, whereas Region 6 has certain wake e£Fects embedded in the
flow. Region 2 is representative of the Bernoulli pressure drop as the
flow velocity increases over the nose of the model. Region 3 is the pressure
gradient along the model length. Sometimes this occurs as a definite
two-slope region, indicating the possible existence of laminar and turbu-
lent flow regimes. Region 4 is usually present but to varying degrees.
It is due to an over-expansion of the flow at the model base and acts
14
(+)
REGION
0©
{-)
-POSITION ALONG TEST SECTION -
Figure 5. Sample of a pressure distribution along the tube in the
vicinity of a 50% blockage model
to increase the drag. Region 5 is the pressure recovery as the flow velocity
decreases to downstream conditions.
A great deal of useful information can be obtained from the model's
pressure signature, such as;
(1) Velocity of flow in tube.
(2) Bernoulli pressure drop over model nose.
(3) Efliective flow skin friction coefficient along model and tube
immediately surrounding model.
(4) Pressure drop of flow expanding over base of model.
(5) Pressure recovery in flow downstream of model base.
(6) Eflrect of model wake on pipe flow friction factor.
The characteristics of the model pressure signature are greatly affected
by the model blockage ratio. The tube length affects the signature to
a smaller degree. For the 50% blockage model, there is both a relatively
large initial pressure drop and a large pressure recovery. For the 90%
case, the pressure gradient due to friction along the model and tube
is the dominant characteristic of the pressure signature.
The pressure drop over the nose of the vehicle is about as would be
expected from simple Bernoulli considerations for the 50% blockage
model, but becomes increasingly larger than expected as the model
blockage increases. The pressure recovery downstream of the model
decreases as the model blockage increases in a manner not far off from
the decrease expected from strict theoretical considerations.
15
Effective friction factors on the model and along the tube wall
immediately surrounding the model can be inferred from the pressure
signature of the model. Based upon the limited data analyzed to date,
it appears that the concentric pipe flow approach is better than the flat
plate approach. Not enough data have been analyzed to determine if
there are significant effects on the friction factor due to the variables
investigated (tube length, model length, model blockage, and gas).
16
JPL Quarterly Technical Review Volume 1, Number 2 July 1971
Aerobraking of High-Speed Ground Transportation
Vehicles
W. Marko
Environmental Sciences Division
A JPL-sponsored aerodynamic testing program has been initiated to per-
form initial investigations on the effectiveness of a series of aerodynamic
brakes on a long cylindrical body. The development of the experimental pro-
gram is presented in this article and a description of the model and test
configuration is given. Preliminary results from a low subsonic wind tunnel
test using three standard test techniques are also discussed. A mo^'ing-model
drop-wire facility has been constructed and initial testing is currently under-
way. This data, which more correctly simulates the viscous interactions of
the model with the ground plane, will be compared with the wind tunnel
data and used to develop analytical prediction methods.
Introduction
The significant amounts of kinetic energy present in high-speed ground
transportation vehicles present serious problems during both normal and
emergency operation. Friction braking systems adequate for trains oper-
ating at normal speeds, as well as some proposed nonfriction systems,
are complicated by heat dissipation systems that become even larger as
speeds increase. However, additional braking can be obtained by aero-
dynamic brakes, or panels, which can be attached to the train and
extended when necessary. All energy is dissipated directly to the air
and complicated coolers are not required. In addition, since aerodynamic
forces are proportional to the square of velocity, this type of braking
rapidly increases in effectiveness as speed increases. While the effect of
a single brake located near the front of a vehicle can be estimated with
confidence, little is known of the effects of a cascade of such brakes
spaced along the entire length of a long vehicle.
The flow disturbances created by a brake are expected to decrease the
effectiveness of any succeeding brakes. Recommendations have been
made in References 1 and 2 that an aerodynamic testing program be
17
undertaken in this area. Because such a small amount of reliable informa-
tion is available, a very simple experiment was developed utilizing ideal-
ized models to yield useful preliminary results that can be applied to
evaluation of the potential of aerodynamic braking as well as to indicate
specific configurations of most promise for further investigation.
Approach
Scale model aerodynamic tests are usually performed in wind tunnels.
In such cases where the vehicle in its normal operation travels near the
ground, the ground boundary is simulated by the insertion of a ground
board in the v/ind tunnel, thereby minimizing the influence of slow-speed
flow near the tunnel wall (boundary layer). Another wind tunnel tech-
nique is to mount two identical models in the unobstructed test area,
one as the mirror image of the other. Both techniques provide only an
imperfect simulation of the ground interaction effects and attempts have
been made with varying success to improve the ground board technique
by removing the boundary layer or providing a moving ground belt.
In the main efforts of this program, a direct approach to the interaction
problem has been undertaken because the turbulence induced by the
extended brakes complicates the problem and makes the need for a more
accurate simulation more important. This is achieved by using a moving
model while the ground plane is stationary. This first generation experi-
mental program uses a 15.24-m (50-ft)^ vertical guide wire in close
proximity to a ground plane and on which simple models of train-like
vehicles (long, circular cylinders) with arrays of extended brakes slide
by means of bearings on the model axis of symmetry. Braking effective-
ness of the arrays will be determined by model velocity measurements
under near-equilibrium conditions; high-speed photography will be used
to investigate local flow conditions on the model. A range of Reynolds
numbers will be obtained by varying the model velocity and the model
diameter. These tests are to be augmented by small-scale wind tunnel
tests.
Wind Tunnel Test Configuration
To minimize the length of the entire program, work was begun on the
small-scale wind tunnel tests while construction of the drop-wire appara-
tus was under way. These wind tunnel tests and the drop-wire apparatus
are now complete. The wind tunnel model is shown in Figures 1 and 2.
It is a basic cj/lindrical model which simulates a train consisting of four
25.908-m (85-ft) cars at a scale of 0.00854. The model length and diameter
1 Values in customary units are included in parentheses after values in SI (Inter-
national System) units if the customary units were used in the measurements or
calculations.
18
Figure 1. Wind tunne! model with brakes
0.8839 m _
(34.8 In.)
0. 868 m
(34.175 in.)
- FIRST BRAKE
■ 3. 1 75 cm
(1.25 In.)
HEMISPHERE NOSE
FLOW
l/MGE MODEL
y
"1 — 1
I
0.610 err
(0.240 in. )-J
3.962 cm
(1.56 in.)
*-
«
3.962 cm
(1.56 in.)
i
^3.175 cm
(1.25 in.)
Figure 2. Schematic of wind tunnel model
19
are 0.8839 m (34.8 in.) and 3.175 cm (1.25 in.), respectively. The rectan-
gular aerodynamic brakes were designed to approximate realistic full-
scale brakes and were also satisfactory from wind tunnel blockage
considerations. Each brake may be located at any point along the length
of the model to obtain the desired spacings.
Three types of tests were conducted. First, a single model was tested
in the center of the tunnel. Second, the original model and a mirror
image were tested in the tunnel. Finally, a single model was tested in
proximity to a fixed groimd plane. Brake spacings were repeated for all
three test configurations. The basic distance between the model and the
ground plane was 0.305 cm (0.12 in.) scaled down from 35.56 cm (14 in.)
full scale. This figure was doubled for the distance between image models.
A sketch of a typical installation in the JPL low-speed wind tunnel is
shown in Figure 3.
60.96 cm
(24 in.)
^ — "ill
SUPPORT
CLAMP
15.24 cm-
(6 in.)
t1
FLOW
I p 0.305 cm
l -i I (0.12 in.
0.610 cm 1 '
(0.24 in.)
IMAGE MODEL ■
30.48 cm — ' (_
(12 in.)
GI?OUND
BOARD
REFERENCE
Figure 3. Wind tunnel model installation
Preliminary Results and Discussion
The primary wind tunnel measurement, axial force, was made with
an internal three-component strain gage balance. Normal force and
pitching moment were also recorded. Data have been reduced to a drag
coefficient based on the model cylindrical cross-sectional area of 7.917 cm-
(1.23 in.-), which is approximately the same as that for one brake.
Figure 4 shows a typical data plot of the drag coefficient Co as a
function of the number of brakes installed on the model at a spacing of
12.7 cm (5 in.). All data with the exception of the first brake point may
be faired smoothly. Differences between the image and ground plane
models clearly illustrates the problem of selecting the proper method
of testing, in a wind tunnel, a vehicle moving over a fixed surface. All
of the results of the wind tunnel test vwU not be discussed here. However,
some effects are noteworthy. Three complete sets of brake spacings were
tested: 7.62, 12.70, 15.24 cm (3, 5, and 6 in.). The total drag on the four-
ear train model was highest for the 7.62-cm (3-in.) brake spacing because
20
z
UJ
U
6
5
/-t
U^^
^
4
3
^<hr- ^cr
^
u
f
Y'
t
y^^
2
_i^
r
12.7-cm (5-in.) BRAKE SPACING
SiNC
;LE MODEL
3E MODEL ~
r
1
D IMAC
4
n
f
O SINGLE MODEL + GROUND PLANE
1 1 1
3 4
NUMBER OF BRAKES
Figure 4. Effect of brake additions
SIDE VIEW
FRONT VIEW
Figure 5. Drop-wire installation
21
of the greater total number of brakes, twelve as compared to seven for
the 12.7-cm (5-in.) spacing. However, the drag increment per brake is
actually less for a 7.62-cm (3-in.) spacing. Other tests concerned the
effect of brake venting in an attempt to add high-energy air to each
succeeding brake in the cascade. The result was a decrease in drag when
10 and 15% of the surface area of each brake was ventilated. Increasing
the clearance between the model and the ground plane resulted in drag
increases which approach the data obtained for the single model in
free air.
The wind tunnel test completes the supporting information necessary
for evaluating the drop-wire program. The primary data, with the moving
model, is now being obtained on the drop-wire system shown in schematic
form in Figure 5. To operate, the model is raised to the top of the wire
guides and released. During the fall, the model interrupts the light beams,
and sensors register the time and distance for the model's passage.
Velocity and corresponding drag coefficient may be calculated from
these data. Model drops will be made with and without a ground plane
for varying brake spacings. A range of Reynolds numbers will be obtained
by varying model terminal velocity and model diameter. Comparison of
these data with those of the wind tunnel experiment is expected to give
significant insight into the problem of brake effectiveness beyond that
of the first brake with a minimum of ground plane viscous interactions.
References
1. Development of Nonfriction Braking Systems for High Speed Trains,
No. YM-2811-K-3. Cornell Aeronautical Laboratory, Inc., Vehicle
Research Department, Buffalo, N.Y., Apr. 1970.
2. High Speed Rail Systems Study by TRW Systems. TRW Inc., Redondo
Beach, Calif., 1969.
22
JPL Quarterly Technical Review Volume 1, Number 2 July 1971
Nitric Oxide Emission Studies of Internal
Combustion Engines
F. H. Shair
California Institute of Technology
J. H. Rupe
Propulsion Division
This article reports on the methods and results of preliminary experiments
that have been conducted with an ASME-CFR (American Society of Me-
chanical Engineers-Committee on Fuel Research ) engine in order to deter-
mine the effect of fuel composition on the emission characteristics of an
internal combustion engine. Initial emphasis was placed upon a comparison
of the nitric oxide emissions within the exhaust for various mixtures of
natural gas and gasoline. A pneumatically driven atomizer permitted tlie
CFR engine to be operated with gasoline fuel-air ratios down to 0.05. At
fuel-air ratios below 0.05, misfiring occurred when either natural gas or
gasoline fuels were used. In a natural gas-gasoline fuel mixture, the nitric
oxide concentration in the emissions decreased almost linearly with increas-
ing concentration of natural gas, based on a fuel-air ratio near 0.063. It is
shown, for the limited conditions investigated, that the concentration of NO^,
in the exhaust (on the basis of mass discharged for unit work done) is
always less when natural gas is the fuel, except for a limited range of
operation at very lean equivalence ratios where misfiring precluded a direct
comparison. However, the emissions were never reduced by more than V4,
and were limited to approximately 20% over a substantial part of tlie
equivalence ratio range (1.0 < < 1.3).
Introduction
The development of a low pollution engine for automotive applications
that will meet or surpass the 1975-1980 standards set forth in the Cali-
fornia Pure Air Act of 1968 (AB 357) is fraught with compromise.
Proposals varying from minor modification of the internal combustion
engine, including add-on devices for exhaust gas treatment, to outright
substitution with, for example, external combustors (fossil-fueled steam
engines) or electric cars (ultimately based on nuclear reactors as an
23
energy source) are many and varied. Although the latter approach may
ultimately be implemented, it seems clear that the current national invest-
ment in the internal combustion engine and the substantial half-life (3
to 5 yr, assuming 100% changeover for all new units starting at some
arbitrary time) of this system dictates a near-term solution based on the
former approach. Thus, it is essential that the potential improvements
that are available with minor engine modifications (preferably suitable
for retrofit to existing vehicles) and/or fuel composition be thoroughly
evaluated. It was to this end that a series of experiments were initiated
as a part of the activity of the "Low Pollution Vehicle Study Group,"
wMch includes JPL staff and California Institute of Technology (Cal-
tech) faculty. The bulk of the experimental work is being carried out
by Caltech students.
In view of the recent interest in the use of natural gas (NG) as a
substitute for gasoline, the first set of experiments was devised to com-
pare emission characteristics from a given engine when run alternately
on gasoline and natural gas. Previous results have demonstrated sub-
stantial improvements for multicylinder engines where manifolding (1)
introduces severe complications for liquid-fueled systems (based on
normally aspirated carburetors), and (2) enhances mixing for gaseous-
fueled systems. These results may be more representative of manifolding
effects than "composition"; hence, an investigation to determine whether
or not composition per se would materially alter emission characteristics
was initiated.
The results reported here are concerned only with the formation of
NOx as a function of inlet fuel composition for a given set of engine
operating conditions. Analogous measurements of CO, CO2, and unburned
hydrocarbons were also obtained but these results are not included in
this report.
These initial experiments have shown that mixtures of natural gas
and gasoline do not produce a significant synergistic effect and that
replacing gasoline with natural gas results in reductions in peak levels
of about 24% in terms of NO^; in grams per kUowatt-second (g/kW-s)
(see discussion of results for this extrapolation). However, the reduction
in available power is substantial. Further, it is shown that with well-
atomized gasoline, it would be possible to control mixture ratio so as to
achieve even lower NOi emissions at greater efficiencies with gasoline
than with natural gas.
It should be emphasized that these results in themselves cannot
preclude the desirability of utiMzing natural gas in internal combustion
engines. As noted above, the emissions of NOi are reduced, and it can be
argued that the compromises associated with reduced power output can
be offset by reductions in hydrocarbon reactivity index for emissions
from natural gas combustion. Any particular conversion must also con-
24
sider such factors as economy of operation, availability of natural
resources, and fuel supply and distribution.
It is noted that these observations are for a limited set of operating
conditions and are therefore restricted by those limits.
Experimental Methods
The experiments reported here were conducted with an ASTM-CFR
(American Society of Mechanical Engineers-Committee on Fuel Research)
single cylinder engine running throttleless (full throttle) at a constant
900 rev/min. The engine was motored except when brake-horsepower
measurements were being made. Initial testing was done with a com-
pression ratio of 7 and with a constant spark advance of 10 dag.
The original variable float level carburetor was replaced by a fuel
injection system to allow the blending of air, natural gas, and gasoline.
To this end the induction system was modified to incorporate a pneu-
matically driven liquid atomizer of conventional design (Spraying
Systems Company Model No. lA). The atomizer was operated so as
to assure a mean drop size less than 20 fxm^ and to yield a mixture that
would behave essentially like a gas. In addition it was mounted in a tube
bolted directly to the inlet flange of the engine so that liquid deposition
on walls was minimized.
Provisions were made to vary the composition of the fuel from 100%
gasoline to 100% natural gas in an attempt to (1) evaluate the potential
of the so-called mixed or dual systems that are being proposed
(Reference 1), and (2) determine whether or not adding small amounts
of natural gas to gasoline could yield disproportionate benefits for a
fuel comprised of a mixture of natural gas and gasoline. For these latter
experiments the working fluid for the pneumatic atomizer became a
mixture of natural gas and compressed air (infinitely variable from
to 100% natural gas) so that the atomization characteristics of the gasoline
were maintained nearly constant. Thus, in summary, the induction system
provided a common source for the injected fuel which could be composed
of any ratio of natural gas/gasoline at any desired fuel-air ratio. The
system will also be utilized in future experiments to evaluate the effects
of mean drop size per se on combustion and emission characteristics.
Fischer-Porter rotameters were used to monitor the mass flow rates.
A disc brake torquemeter was installed to allow measurement of the
output power developed by the engine. A mixing tank (with a volume
equal to approximately 35 cylinder volumes) was installed in the exhaust
line to eliminate problems of concentration stratification.
^Presumed from manufacturer's specifications alone; not proven.
25
On-line analysis of the exhaust products was achieved with a high-
speed, quadrapole, mass spectrometer (E.A.I. Quad 300) monitoring the
effluent from a, sampling probe installed downstream of the mixing tank.
This system was used to measure, with relative precision, the concentra-
tions of NO, CO, CO2, CH4, and CMo.
In order to aid in the measurements of the higher hydrocarbon
emissions, a Carle Model 9000 gas chromatograph (with a flame ionization
detector) was also arranged so as to permit on-line sampling of the
exhaust. The electrical signals from the gas chromatograph were: (1) inte-
grated by means of an Infotronics Model CRS-100 digital integrator,
and (2) displayed on a Hewlett-Packard Model 7127A strip chart recorder.
This system is providing excellent data on hydrocarbon emissions, but,
as indicated previously, this information is not included in this report.
As shown in Figure 1 a control panel is used to control and monitor
flow rates of air and fuels flowing to the CFR engine; the disc brake
and the on-line mass spectrometer are in the background, whereas the
on-line gas chromatograph system (although present) is not visible in
the picture.
Figure 1. CFR: engine and instrumentation for determining exhaust emissions
Experimental Results
The concentration of NO^ in the exhaust versus fuel-air ratio for this
engine is shown in Figure 2; the curve with a maximum at approximately
2S
z
o
o
z
5000
4500
4000
3500
3000
2500
1500
1000
500
0.04
0.05
0.06 0.07 0.08
FUEL-AIR RATIO
C.09
0.10
Figure 2. NO^. concentration in exhaust of an internal combustion engine
burning natural gas or gasoline
4200 ppm is that obtained for several gasolines purchased at random
from local outlets, whereas the other curve is for natural gas, nominally
composed of 90% CH4 + 9% C^He + residual CH + H,. The stoichio-
metric fuel-air ratio for these gasolines is near 0.0645 and for natural
gas is 0.0578. Where there is overlap, there is good agreement between
27
these results and those reported previously (for example, see Figure 4
of Reference 2).
Figure 3 indicates how the concentration of NOa, varies with the per-
cent of natural gas in the fuel. These data are being analyzed with respect
to tlieoretical models put forth by Newhall (Reference 3) and by Lavoie,
Heywood, and Keck (Reference 4). Tests are planned to determine the
comparable lean limit equivalence ratio associated with the original
CFR carburetor system.
4000
o
CFR ENGINE
FULL THROTTLE
900 rev/min
SPARK ADVANCE = lOdeg
COMPRESSION RATIO = 7.0
FUEL-AIR RATIO = 0.0633 ±0.0016
250C
2000
1000
40 60
NATURAL GAS IN FUEL, %
Figure 3. NO^. concentration in exhaust of an internal combustion engine
burning mixtures of gasoline and natural gas
A comparison of engine performance, in terms of brake horsepower
and specific fuel consumption versus fuel-air ratio, for natural gas and
gasoline is presented in Figure 4. Clearly, the characteristic reduction
in horsepower and the associated increase in specific fuel consumption
(which is partially offset by the increase in heat of combustion) when
burning natural gas are not negligible. Therefore, a proper comparison
28
0.16
5
<
0.14
0.12
0.10
0.08
o
z
o
z
0.04
0.05
0.06 0.07 0.08
FUEL-AIR RATIO
0.09
0.10
Figure 4. CFR engine performance with gasoline and natural gas
of the emission characteristics of these two fuels should incorporate the
effects of this compromise.
It should be emphasized that Figures 2 and 3 deal excliisivel)/ with
NOj; formation; other data are being reduced wherein consideration is
given to the photochemical reactivity associated vwth the hydrocarbon
product distribution.
Discussion of Results
When these data are presented as in Figure 2, it is observed that: (1)
gasoline produces substantially greater quantities of NO^ than does
natural gas for fuel-air ratios greater than about 0.057; (2) for fuel-air
29
ratios leaner than about 0.057, the emission levels for these two fuels
are similar; and (3) for fuel-air ratios less than about 0.053, gasoline
actually produces lower emission levels than does natural gas. Thus, it
can be argued that emission levels for natural gas are similar to gasoline
for lean, fuel-£iir ratios but substantial reductions in NO^ formation are
available for fuel-rich operation — even though, as illustrated in Figure 4,
the compromises in terms of fuel economy (cost) and horsepower (engine
size) are costlier for fuel-rich operation. It follows, then, that with well-
atomized gasoline, the benefits to be derived by substituting natural
gas for gasoline as an automotive fuel must stem from operation in the
fuel-ricli condition, not the lean condition, as is commonly stated.
It is of interest to point out that these conclusions must be modified
somewhat if the comparison is based on the equivalence ratio rather
than the fuel-air ratio. Thus, when the concentration data of Figure 2
are converted to an emissions rate, in terms of NOj, in grams per hour
(g/h), and the comparison of emissions and engine performance por-
trayed as a function of fuel equivalence ratio- (as illustrated in Figures 5
and 6), it can be seen that the emission levels for natural gas always fall
below those for gasoline. Further, substitution of natural gas for gasoline
produces a nearly constant 28-30% reduction in available horsepower
over the entire range of equivalence ratios, and the compromise asso-
ciated v/itti inel economy is no longer so mixture ratio dependent — except
that it is "desirable" to operate at or near equivalence ratio unity where
the penalty, in terms of increased specific fuel consumption, for converting
to natural gas is limited to approximately 14%.
It is interesting to note that, on an equivalence ratio basis, the lean
stability limit for the "well-atomized" gasoline system is even lower than
that for natural gas. Hence, the potential for controlling emissions by
operation with "Lean air-fuel mixture carburetion . . . achievable by
means of air-fuel mixture homogenation," as concluded by Kopa (cf
Reference 5), is also demonstrated in these experiments with the CFR
engine. Note that a similar conclusion is not strictly true when natural
gas is the fuel. As seen in Figure 5, substantial amounts of NO^^ are still
being produced at the lean stability limit and it follows therefore that
the only way to reduce these emissions further is to operate in the
relatively rich, region where the fuel-air equivalence ratios exceed
approximately 1.18.
If the data of Figures 5 and 6 are combined to reflect the emission rate
in terms of the work done, as shown in Figure 7, then the relative ad-
vantages associated with substitution of natural gas for gasoline are
further reduced. It can be seen that if the comparison is made at their
respective maxima, natural gas produces approximately 76% as much
-'Fuel equivalence ratio (p is equal to the fuel-air ratio divided by the stoichiometric
fuel-air ratio.
30
1.
2
O
<
O
2
64
56
48
40
/~
/
\ FULL THROTTLE
\ 900 rev/min
\ SPARK ADVANCE = lOdeg
\ COMPRESSION RATIO = 7.C
f (STOICHIOMETRIC FUEL-AIR
\ RATIO = 0.0645)
32
^
NiATURAL GAS
(STOICHIOMETRIC FUEL-AIR
RATIO = 0.0578)
/
/
/
/
24
\ \
/
\ \
\ \
\
\
\
f f
\
\ \
1
J^ — LEAN LIMITS
/
y^
f
FUEL RICH —
\ \
\
■\ ^~^
"~~-
0.6
0.8 1.0 1.2
Figure 5. NO^, emission from CFR engine for two fuels
31
z
o
z
4.U
3.5
^^
^ —
3.3
~/
/
.
2.5
/
2£
%
/
_
/
/
/
/■
/
/
/
' FUEL RICH —
1.5
1 1
0.6
1.0
1.4
1.6
Figure 6, CFR engine performance as a function of fuel equivalence
ratio with gasoline and natural gas
NOj; as does gasoline. However, this ratio rises to approximately 90%
over most of t'he fuel-rich region.
The "relative" emission rates for the two fuels is illustrated in Figure 8,
where it can be seen that gasoline always produces more NO^. However,
the difference is only about 8% at the minimum and does not exceed
20% for a rather broad range of equivalence ratios. Further, the data
do not allow a comparison at the lean limit where the ratio would
32
28
24
FULL THROTTLE
900 rev/mi n
SPARK ADVANCE = lOdeg
COMPRESSION RATIO = 7.0
0.6
1.4 1.6
Figure 7. NOj, emission as a function of fuel equivalence ratio from
CFR engine for two fuels
33
z
^
CI
u
z
<r
Qi
O
u
n
z
Lu
u
7
O-l
n
—
i
^
o''
^
z
<)
Z
,
2.2
2.0
".S
1.6
1.4
1.2
1.0
0.8
CFR ENC
,INE
raTTLE
Tiin
DVANCE= 10
SSION RATIO
1
FULL TH
900 rev/
SPARK A
COMPRE
deg
= 7.0
1
1
1
1
1
1
\
/
1
/
1
\
1
1
1
v^
1
K
1
1
.^—EXTRAPOLATED BEYOND LEAN
STABILITY LIMIT FOR NG
FUEL RICH — »-
0.6
1.0
1.2
1.4
1.6
Figure 8. Relative NO^. emission for gasoline and natural gas fuels
doing same work
(apparently) be less than 1.0. One should also note that in the fuel-rich
regions the absolute emission levels are small for both fuels (see Figure 7).
Conclusions
Preliminary results of this study have shown that:
(1) The substitution of natural gas for gasoline as the fuel for an in-
ternal combustion engine:
(a) Yields fractional reductions in peak NO^ emissions for a given
amount of work done.
(b) Compromises available horsepower by about 28%.
(c) Imposes a requirement that the engine be run rich (not lean)
in order to minimize NO^.
34
(2) The lean stability limit equivalence ratio for gasoline is less than
that for natural gas if an efficient atomizer is utilized.
(3) The figure-of-merit for any pollutant cure must reflect the useful
work done.
(4) Mixtures of natural gas and gasoline do not produce any appre-
ciable synergistic effect insofar as reduction of NO-c is concerned.
References
1. Mcjones, R. W., and Corbeil, R. J., "Natural Gas Fueled Vehicle Ex-
haust Emissions and Operational Characteristics," SAE Paper 700078,
presented at the Automotive Engineering Congress, Detroit, Mich.,
Jan. 12-16, 1970.
2. Eyzat, P., and Guibet, J. C, A l<Iew Look at Nitrogen Oxide Formation
in Internal Combustion Engines, SAE Report 680124. Society of Auto-
motive Engineers, New York, 1968.
3. Newhall, H. K., "Kinetics of Engine-Generated Nitrogen Oxides and
Carbon Monoxide," presented at the 12th Symposium (International)
on Combustion, the Combustion Institute, Pittsburgh, 1968.
4. Lavoie, G. A., Heywood, J. B., and Keck, J. C, "Experimental and
Theoretical Study of Nitric Oxide Formation in Internal Combustion
Engines," Combustion Science and Technology, Vol. I, pp. 313-326,
1970.
5. Kopa, R. D., "Control of Automotive Exhaust EmissioiQ by Modifica-
tions of the Carburetion System," SAE Paper 660114, presented at the
Automotive Engineering Congress, Detroit, Mich., Jan. 10^14, 1966.
35
JPL Quarterly Technical Review Volume 1, Number 2 July 1971
kn All-Carbon Radiating Nozzle for Long-Burning
Solid Propeilant Motors
R. L Bailey and J. I. Shafer
Propulsion Division
Three 27 -kg solid propeilant motors have been static-fired in three tests
to demonstrate the feasibility of using nozzles based on all-carbon composite
materials for long-burning, high-performance solid rocket propulsion systems
suitable for planetary orbit-insertion applications. The successful completion
of these firings represents a significant advancement in long-burning solid
propeilant nrotor technology in that : ( 1 ) the motor burning times are com-
parable to tliose required for space missions; (2) the nozzle weights are
about 0.4-0.6 that estimated for equivalent flight-vi^eight ablative nozzles;
and (3) unlike the ablative nozzles, the all-carbon radiating nozzles can be
reused without, or with only very limited, refurbishment. Additionally,
thermal analysis indicates that the nozzle design is acceptable when ap-
plied to a scaled-up 355-kg motor with a total burning time of 150 s (the
desired time). The all-carbon radiating nozzle design, fabrication, testing,
and analysis activities are described in this article.
Introduction
For solid propeilant motors to meet the requirements of attitude-
stabilized spacecraft for planetary orbiter missions, they must have both
high performance and abnormally long burning times of up to 125-250 s
(References 1-3). For a given motor, as the burning time is increased,
one intuitively believes that a non-ablating radiative nozzle would, at
some point, prove to be superior (Hghter) than the ablative nozzles now
in use. This assumes, of course, that the nozzle can be efficiently isolated,
or insulated, from its thermally sensitive rocket motor chamber and that
the severe thermal environment can be made acceptable to nearby space-
craft components.
A non-ablating radiative nozzle that utilizes all-carbon composite
materials recently developed by industry has been designed and fabricated.
36
Feasibility tests have been conducted on a 27-kg (60-lb)' flight- weight
sohd propellant motor having a burning time of about 45 s. Ultimatel]/,
a scaled-up version of the nozzle will be used in a demonsti-ation firing,
at simulated altitude, of a 355-kg (780-lb) orbit insertion motor with a
burning time of 150 s. (An artist's rendering of the demonstration motor
with the proposed all-carbon nozzle is given in Reference 4.)
Nozzle Design
Carbon filaments belong to a class of materials typically prepared
from synthetic (e.g., rayon) fibers that, under controlled thermal decomposi-
tion in an inert atmosphere (i.e., pyrolysis), yield the desired carbon class
of filaments. When advantageous, the carbon filaments may be graph-
itized in order to orient the carbon crystal structure to alter mechanical
and thermal properties in preferred directions.
Carbon (graphite) filaments have been available for some time. How-
ever, the all-carbon composite class, i.e., the carbon (graphite) filaments
or cloth in a carbon (graphite) matrix, is quite new, and there are several
preparation processes under development by various manufacturers. The
nozzle design described here capitalizes on the unusual properties of these
carbon composites.
The mechanical strength and elongation of these materials increase
with increasing temperature up to and above 3030 K (5000 °F). The me-
chanical and thermal properties are anisotropic; e.g., heat transfer across
the fibers is significantly lower than that along the fibers. The tensile
and compressive strengths are reasonably high, but the interlaminar
shear, at present about 1380 N/cm^ (2000 psi), is the weakest property
and strongly influenced the design. These materials, as fabricated, are
somewhat porous (density of about 1.44 g/cm^ versus 1.9 for high-
density bulk graphite), but the strong reinforcement fibers contribute
markedly to toughness, an important factor during handling and ignition
of the motor.
In the chemically reducing atmosphere typical of solid rocket com-
bustion gases, these composites are relatively inert so nozzle erosion was
expected to be low. Sublimation temperature reportedly is about 3922 K
(6600 °F), well above the flame temperature of the propellant system
used for the design.
The nozzle assembly (Figure 1) includes a laminated nozzle body of
pyrolyzed graphite tape fabricated by the rosette pattern technique, a
high-density graphite insert for the throat for maximum erosion resist-
ance, and a laminated conical transition section of graphite tape oriented
^Values in customary units are included in parentheses after values in SI ( Interna-
tional System) units if the customary units were used in the measurements or
calculations.
37
PROPELLANT
IFLAME TEMPER-
ATURE = 3161 K
(5230°F)|
Figure 1. Configuration of all-carbon nozzle for feasibility testing
to minimize heat transfer. The transition, when mated to the chamber,
supports the nozzle in a submerged position. Its gas seal at the chamber
is a silicone 0-ring; the seal at the threaded nozzle joint is a graphite
gasket and ceramic cement. The thickness of most of the expansion cone
is only 0.165 cm (0.065 in.), the minimum that could be fabricated with
confidence at the time the nozzle was produced.
In the design philosophy adopted, the extremely hot nozzle was
retained by providing a long enough heat path along the conical transi-
tion section such that the heat-treated chamber would not be weakened
unacceptably during the heating transient of the required burning time.
Obviously, the transition section, with this design requirement, must be
insulated on its lateral surface from propellant combustion gases of
3161-K (5230°F) temperature. A low-density (0.9-g/cm^) ablative com-
posite based on a phenolic-impregnated paper carbon serves as insulation.
Nozzle Fabrication
Success of the all-carbon nozzle work depended strongly on the knowl-
edge and experience of industry, especially regarding material choice
and nozzle fabrication procedures; design and feasibility testing were
JPL's responsibility. Early development efForts were based on a filament-
wound graphite nozzle body, but it was found that, during a late
processing step (high-temperature graphitizing), significant cracks or
delaminations developed or porosity proved to be unacceptably high
38
in the pyrolyzed part. Subsequently, Reflective Laminates, a division of
Fansteel, Inc., succeeded in producing satisfactory nozzle components
by using graphite cloth in place of the filament-vi^ound graphite.
Materials and procedures were specially designed for the fabrication
of the carbon-to-carbon bonded structures. During processing, the inter-
laminar bond strengths are reduced, and the shrinkage stresses of the
components increase. Therefore, procedures had to be tailoj-ed to process
the components through these critical cycles without producing cracks
or delaminations. The fabricator reported that the final part must be
stress-relieved if interlaminar shear values in excess of 1380 N/cm-
(2000 psi) are to be produced.
Figure 2 illustrates the method used for producing the oriented lam-
inated transition and the rosette-pattern laminated nozzle body. In
essence, the procedure for producing these components consists of:
(1) making a large flat-plate laminated block and a thick-walled rosette-
patterned laminated cone out of graphite cloth impregnated with phenolic
resin, (2) rough-machining the two components from the block and cone,
(3) subjecting these components to temperature pyrolyzing cycles, and
(4) machining the components to their final configuration. The laminates
are oriented in the block to increase the thermal resistance between
the inside and outside diameters of the transition. The rosette pattern
FINAL CONFIGURATION
OF NOZZLE TRANSITION
(NOT TO SCALE)
-FLAT-PIATE
LAMINATED
BLOCK
FINAL CONFIGURATION
OF NOZZLE BODY
(NOT TO SCALE)
ROSETTE-PATTERN
LAMINATED
CONE
Figure 2. Layup step in nozzle transition and body fabrication
39
in the thick cone helps minimize shrinkage stresses and delaminations
during the pyrolyzing steps.
The selection of a preimpregnated graphite cloth for making the
block and thick-walled cone of Figure 2 was based on special require-
ments to produce uniform pyrolyzed components. The fabric must be
selected for weave conditions and thermal stability of the fibers. The
impregnating resin must have good char-forming characteristics with
minimum shrinkage during polymerization. The resin solids content,
volatiles, and flow must be carefully controlled in the preimpregnated
stage. The product meeting those requirements was a highly heat-treated
graphite cloth impregnated with a phenolic resin with a solids content
of 20--30% and a maximum volatile content of 4%; the cured minimum
density was 1.4 g/cnr''.
To obtain the required minimum density in the block and cone, several
debulking cycles were performed at increasing pressures, but at tempera-
tures low enough to prevent cure in the preimpregnated material. The
block and cone were then cured at high pressure at 436 K (325°F) and
subsequently post-cured at 506 K (450°F).
Following cure, the individual nozzle components were rough-machined,
radiographed for cracks or delaminations, and subjected to a series of
pyrolyzation cycles that carbonized the resin. Reimpregnation with a
plienol-furfurol-based material after each cycle gradually raised the
component density to that required. A final graphitization cycle was
performed at 3030 K (5000°F).
The components were again radiographically inspected for cracks or
delaminations and were then machined to finished dimensions. Another
radiography inspection preceded the assembly of the components into
the final configuration.
Static-Firing Test Results
The two finished nozzles were subjected to a total of three static-firing
tests using flight-weight motors; the test conditions and results are sum-
marized in Table 1. During the first test, conducted March 26, 1970,
using nozzle SN-1, much of the nozzle body operated in a "white hot"
mode for approximately 35 s of the 47-s burning time. After the firing, an
inspection revealed no cracks or delaminations in the all-carbon transi-
tion and nozzle body sections and only small delaminations in the
phenolic -impregnated paper carbon insulation. The nozzle was, in fact,
judged to be in such good condition that it was subjected to another
static firing test without refurbishment.
40
Table 1. Static-firing test conditions and results
All-carbon nozzles
Ablative
nozzle
Item
Test 1
(SN-1)
Test 2
(SN-1)
Test 3
(SN-2)
Propellant weight, kg
Simulated altitude, km
26.65
Sea level
25.42
Sea level
26.65
15.90
27.57
15.90
Motor burning time, s
Nozzle expansion ratio e
Maximum chamber pressure,
N/cm2
47
53.5
196.6
45
40.3
146.3
48
40.4
157.4
20
35
172.5
Nozzle weight, kg
Initial
1.069
0.909
0.987
1.981
Final
0.928
0.869
0.924
1.776
Throat diameter, cm
Initial
2.533
2.920
2.916
4.445
Final
2.635
2.998
2,954
4.465
The second firing resembled the first, except that the nozzle throat
diameter was increased in order to test the motor and nozzle at pressure
conditions closer to those desired for the ultimate flight application. The
motor performed as expected. However, after an estimated 30-35 s of
burning, a small rectangular hole (ultimately about 2.5 cm X 5 cm)
developed in one side of the exit cone, at an expansion ratio e s; 9, just
downstream from the nozzle attachment ring plane. Since thrust was not
being measured, the hole had no adverse effect on the motor performance.
After sectioning the nozzle, the thickness at the edge of the hole was
found to average 0.095 cm (compared with a fabricated thickness of
0.165 cm); no change in the internal diameter of the nozzle was noted.
It was concluded that, since the nozzle was exposed to the air during
the test, rapid oxidation on the outer surface of the cone i-esulted in the
weak area and subsequent formation of the hole. It is believed that the
nozzle would not have failed if the atmosphere had been inert or absent.
The rest of the nozzle, especially the transition section, showed no
abnormal effects after a cumulative 91 s of testing.
A third test, using nozzle SN-2, was made under simulated altitude
conditions in order to test the high-expansion-ratio cone at full flow
and to verify that the cone thickness, without oxygen exposure, would
remain unchanged. Figure 3, a photograph taken about 30 s into the
firing, shows the nozzle exhausting downward into the diffusor and illus-
trates the typical temperature gradient along the expansion cone. This
nozzle was also found to be in excellent condition after testing, as shown
in Figure 4. No cracks, delaminations, or changes in cone thickness from
oxidation could be detected upon post-fire inspection. It is currently
planned to refire this nozzle.
41
■-: .-.
■is.
Figure 3. All-carbon nozzle during simulated altitude firing
(b)
-2'4i^^^.'
Figure 4. All-carbon nozzle (a) before and (b) after simulated altitude firing
42
These all-carbon nozzles are about the same size as the flight nozzle
used successfully on the JPL Syncom apogee kick motor (SR-12-1). Typi-
cal 1964 test results of the Syncom nozzle are also presented in Table 1
for comparison purposes. The Syncom motor used an ablative nozzle
that was fabricated with a randomly oriented carbon-phenolic material.
It was approximately 100% heavier than the all-carbon nozzles. It
should also be noted that the Syncom nozzle could be used for only one
motor firing of 20-s duration.
Figure 5 illustrates the nozzle surface temperature variation with
time as measured by two infrared radiometers during the second SN-1
firing and the SN-2 firing at altitude. During the SN-1 nozzle test, the
radiometers were focused at station 1, where 6 = 7 (i.e., about 2.5 em
downstream from the nozzle-to-transition joint). During the SN-2 nozzle
test, one radiometer was focused at station 1 and the other was focused
at station 2, where e ^ 27 (i.e., 7.6 cm upstream of the nozzle exit), The
maximum temperature measured at station 1 was about 1845 K (2860°F);
that at station 2 was about 1666 K (2540°F). These values agree within
about 55-83 K (100-150°F) to the predicted temperatures at those sta-
tions-good agreement considering the limited data available on the
thermal properties of these newly developed materials and the radiom-
eter accuracies under the test conditions.
Conservative calculations were made to determine whether radiation
losses would contribute significantly to a loss in specific impulse. They
E = EXPANSION RATIO
STATION 1,
ALTITUDE FIRING
-STATION 1, SEA- ALTITUDE FIRING ^-~C:^^
LEVEL FIRING "~ ~^^^-?.5. :~ ~ _
h END OF FIRING -=■■==-:=.;
J LJ L_ L L,^_J \ J
100 1/ 200 400 600 800
20 40 60 80
TIME, s
Figure 5. Measured nozzle surface temperatures during and after static
firing of flight-weight motor
43
showed that: (1) such losses, based on measured heat fluxes from the
nozzle, did not exceed 0.6%; and (2) total nozzle heat losses did not
exceed 1.2%, a typical value for small ablative flight -weight nozzles. A
separate determination of the loss in specific impulse due to combustion
gases flowing radially outward through the relatively porous walls of
the nozzle cone revealed that such a loss was insignificant (<0.1%).
Thus, the use of all-carbon radiating nozzles would not appear to have
a deleterious effect on motor performance.
Thermal Analysis of Scaled-Up Nozzle
Ultimately, a 355-kg motor utilizing a scaled-up version of these all-
carbon nozzles will be tested. In preparation for the firing of this motor
with a 150-s burning time, a thermal analysis of a full-sized nozzle was
made. Basicalty, the design used the same materials and concepts as
those of the small-nozzle design. However, a sandwich-type heat shield
[i.e., 1.3-cm-thick, low-density (0.08-g/cm'') carbon felt between alumi-
num plates, each 0.051 cm (0.020 in.) thick] was introduced to protect
the aft end of the motor case. In addition, a 0.63-cm-thick (0.25-in. -thick)
layer of low-density carbon felt was incorporated as a thermal barrier
between the transition and nozzle cone. The thermal model was set up
and analyzed by Dr. L.-C. Wen of JPL, using the CINDA computer
program, which is capable of handling combined conduction, convec-
tion, and radiation for transient and steady-state conditions.
Figure 6 plots the predicted temperature versus time at five stations
on the nozzle body and five stations on the conical transition member.
The calculations indicate that, at the end of burning, the nozzle cone
temperature will vary from 2390 K (3842°F) near its junction with the
transition to 1140 K (I592°F) near the nozzle exit. The transition mem-
ber easily provides the pronounced temperature gradient needed to
protect the chamber. The temperature of the chamber at the nozzle
attachment point is expected to be only 375 K (215 °F), an acceptable
design value. The aluminum heat shield at node 184 should reach 547 K
(525 °F), well below its melting point. The temperature of the shielded
case will rise an insignificant amount due to heat from the nozzle; e.g.,
node 150 should rise about 1-2 K.
Separate computer runs revealed that motor burning times up to
200-225 s are feasible with the indicated basic design for very small
increases in insulation weight, provided the chamber pressures are kept
low. It is of interest to note that the total nozzle, including insulation
and heat shield, is estimated to weigh 9.8 kg (21.5 lb). That weight can
be compared with 16.6 kg (36.5 lb) for a lightweight ablative nozzle
designed as an alternative to the all-carbon nozzle.
44
00 120 140
TIME, s
Figure 6. Predicted nozzle temperatures during firing of
355-kg demonstration motor
45
Conclusions
From tlie information obtained thus far, it can be concluded that:
(1) Fabrication technique is a critical factor affecting the integrity of
all-carbon nozzles; Reflective Laminates has demonstrated a satis-
factory technique for nozzles of the size tested.
(2) An all-carbon nozzle can be reused several times, which, in effect,
compensates for its initial high cost.
(3) The use of submerged all-carbon radiating nozzles for high-
performance solid propellant motors is technically feasible and
very promising.
References
1. Robillard, C. L., and Cork, M. J., "Mission Analysis for Solid Propellant
Motors on Unmanned Spacecraft," AIAA Paper 68-815. American
Institute of Aeronautics and Astronautics, 1290 Avenue of the
Americas, New York, N. Y. 10019.
2. Don, J, P., and Shafer, J. I., "Outer Planet Orbiter Propulsion," CPIA
Publieatioa 196, Vol. I. Chemical Propulsion Information Agency,
Johns Hopkins University, 8621 Georgia Ave., Silver Spring, Md.
3. Shafer, J. L, "Long-Burning-Time Motors for High Incremental-
Velocity Maneuvers at Low Acceleration," CPIA Publication 188,
Vol. I. Chemical Propulsion Information Agency, Johns Hopkins Uni-
versity, 8621 Georgia Ave., Silver Spring, Md. (Confidential).
4. Shafer, J. L, Strand, L. D., and Robertson, F. A., "Low Acceleration
Rate Ignition for Spacecraft," in }PL Quarterly Technical Review,
Vol. 1, No. 1, pp. 35-44. Jet Propulsion Laboratory, Pasadena, Calif.,
Apr. 1971.
46
JPL Quarterly Technical Review Volume 1, Number 2 July 1971
Mariner Mars 1971 Orbiter Propulsion Siubsystei
Type Approval Test Program
J. F. Stocky
Propulsion Division
A new propulsion subsystem was used on the Mariner Mars 1971 orbiter
spacecraft to provide the necessary impulse for trajectory corrections, Mars
orbit insertion, and Mars orbit trim maneuvers. The type approval test pro-
gram that provided the functional, structural, and environmental qualifica-
tion of this subsystem and demonstrated its performance marg:'n in excess
of flight mission requirements is described. A brief discussion of the prob-
lems encountered is included.
Introduction
The Mariner Mars 1971 spacecraft is designed to use the basic vehicle
employed on previous Mariner (fly-by) missions with the incorporation
of a new and larger propulsion subsystem (Figure 1) to decelerate the
spacecraft from a hyperbolic approach trajectory and place it into an
elliptical orbit about Mars. The schematic diagram of this pressure-fed,
bipropellant subsystem is shown in Figure 2. A regulated supply of filtered
nitrogen gas is used to expel the hypergolic fuel (monomethylliydrazine)
and oxidizer (nitrogen tetroxide), each of which is contained in a Teflon
expulsion bladder, from the propellant tanks through a filter to the
rocket engine. Braided, Teflon-lined, flexible hoses are used to permit
gimballing of the rocket engine to provide spacecraft pitch-yaw control.
Positive isolation of the pressurant and propellants is achieved vv-itli
explosively actuated gate valves, which are actuated by ground commands.
Because this propulsion subsystem was new and diflrerent from those
previously used, it was required that it be subjected to a type approval
(TA) test program. Successful completion of this test program would then
qualify the subsystem for the 9-mo mission for which it was designed.
Components identical to those used on the flight spacecraft were
employed in the assembly of the propulsion subsystem to be used for
47
ROCKET ENGINE ASSEMBLY
OXIDIZER ISOIATI ON
VALVE ASSEMBLY
PRE3SURANT CONTROL
ASSEMBLY
FUEL TANK
t^.^..
-STRUCTURE ASSEMBLY
-.1 TROGEN TANK
Figure 1. Fueled and pressurized TA propulsion subsystem ready for vibration
the type approval test program. After assembly this test subsystem was
subjected to the same flight acceptance tests to which the flight sub-
systems were exposed.
The TA test program was conceived and conducted to demonstrate
functional and structural margin and performance capability in excess
of that which will be required of those subsystems to be used for the
flight mission. To this end the test conditions listed below were planned.
(1) Higher level and increased duration for mechanical vibration.
(2) Operation at extreme temperature limits.
48
^
PRESSURANT CONTROL ASSEMBLY
PRESSURANT TANK ASSEMBLY
PYRO-VALVE ASSEMBLY
^ PRESSURANT CHECK AND RELIEF
V ASSEMBLY - OXIDIZER
m
PROPELLANT ISOLATION
ASSEMBLY - OXIDIZER
E = NORMALLY OPEN EXPLOSIVE VALVE
(?) = TEMPERATURE TRANSDUCER
(m) = MANUAL VALVE
K— PROPELLANT ISOLATION
ASSEMBLY - FUEL
(s) = SOLENOID VALVE
[?] = PRESSURE TRANSDUCER
DO -"^ FILTER
iff = REGULATOR
Figure 2. Schematic of Mariner Mars 1971 propulsion subsystem
(3) Two-mission duty cycles.
(4) Extra handling and servicing.
(5) Additional functional and component checks.
(6) Other extended operating limits, such as high tank pressures,
extreme non-operating temperatures, and extreme engine valve
temperatures prior to firing.
Description of Events
The sequence of the TA program v^^as as listed below.
(1) Component acceptance tests.
(2) Flight acceptance tests of subassemblies, conducted to verify proof
of workmanship, quality, and performance characteristics of the
subassemblies.
(3) Flight acceptance tests of the propulsion subsystem, vi'hich included
the tests listed below.
(a) Subsystem fabrication and assembly.
(b) Proof pressure test.
(c) External leakage test.
(d) Functional test (regulator, valves).
(e) Vibration test, loaded with solvents to simulate propellant mass.
(f) Acoustic test, simulating launch environment.
(g) Bladder leakage test.
(h) External leakage test.
(!) Functional test.
(j) External leakage test.
The above tests were the same as those that all flight subsystems
experienced prior to the actual mission. Then, to simulate mission
conditions, Test Series 1 and 2, as outlined in Tables 1 and 2, were
performed.
Test Series 1 and 2 simulated two-mission duty cycles. The fact that
the pyro valves were irreversible in operation precluded a complete
simulation, so the sequences were folded, as shown in Tables 1 and 2.
The total engine firing time of each test series exceeded that expected
for flight. Therefore, the engine, filters, bladders, and service valves
demonstrated margin in capacity and cycle capability. The extra handling
and servicing required for two propellant loadings and unloadings
50
Table 1. Test Series 1 (high temperature)
Test sequence
Simulated mission sequence
1. Propellant vibration (Saxes)
2. Installation in vacuum chamber
3. Open and close engine valve
4. Pyro valves open (-1 series)
5. 8-s firing
6. 1-day hold
7. Pyro valves close ( -2 series )
8. 1-day hold
9. Pyro valves open (-3 series)
10. 10-s firing
11. 1-day hold
12. 900-s firing
13. 2-day hold
14. 0.4-s firing
15. 3-day hold
16. 40-s firing
17. Not performed
Laxmch
2-wk coast
Liquid line vent
Pyro valves open ( -1 series )
Midcourse 1 firing
1-wk coast
Pyro valves close ( -2 series )
6-mo coast
Pyro valves open ( -3 series )
Midcourse 2 firing
20-day coast
Orbit insertion firing
2- to 4-day coast
Orbit trim 1 firing
2- to 4-day coast
Orbit trim 2 firing
' Coast
; Pyro valves close
, Orbit planet
qualified the techniques and subsystem in the case of offloading propel-
lants for repairs prior to launch. The engine was heated to 338.7 K
(150°F)^ prior to the first midcourse firing, approximately 11 K (20°F)
hotter than that predicted from solar radiation; the subsystem was heated
to 303.7 K (87°F), near the maximum of its specified range [305.4 K
(90°F)] and 6.7 K (12°F) warmer than that predicted for the first mid-
course maneuver. Cold propellants were then loaded for Test Series 2,
and the propellants were at 280.3 K (45 °F) at the time of the orbit
insertion firing, compared to an expected temperature of 297 K (75 °F).
These temperature extremes were intended to demonstrate margin for
bladder collapsing, engine valve operation, check valve operation, and
the operation of other temperature-sensitive components. Saturated pro-
pellants were not used for testing, since analysis had shown that the
predicted level of saturation at the time of orbit insertion would be well
1 Values in customary units are included in parentheses after values in SI (Inter-
national System) units if the customary units were used in the measurements or
calculations.
51
Table 2. Test Series 2 (Sow temperature)
Test sequence
Predicted mission sequence
1. Not performed
Launch through midcourse 2 firing
2. 900-s fcing
Orbit insertion firing
3. 3-day hold
2- to 4-day coast
4. 16-s firing
Orbit trim 1 firing
5. 1-day hold
2- to 4-day coast
6. Not performed
( Orbit trim firing
1 Coast
7. Pyro valves close
(-4
series )
Pyro valves close ( -4 series )
8. 1-day coast
Orbit planet
(End of
nominal sequence )
9. Pyro valves open
(-5
series )
\
10. 10-s firing
11. 1-day coast
{ Margin demonstration
( operations
12. 20-s firing
)
below the threshold required to affect performance. The orbit insertion
firing of Test Series 2 was performed with propellant tank pressures
initially 17 N/cm^ (25 psi) higher than expected, simulating tank heating
or regulator gas leakage.
Results and Conclusions
Tv/o problem areas were discovered in the subsystem TA program. A
beryllium tube supporting one of the pressurant tanks failed during
vibration with solvents. This occurred at the resonant frequency of the
pressurant tanks, and was due to a higher than expected tank response.
The pressurant tank support tubes were replaced with steel tubes and
were qualified. The oxidizer check valve partially opened during the
first engine firing of Test Series 1, and the oxidizer tank supplied pro-
pellant in a blowdown mode. Operation for later engine firings was
satisfactory. A detailed component test program determined the cause
of the check valve sticking to be interference between the Teflon poppet
and the metal poppet guide, due to oxidizer absorption and thermal
growth of the poppet. Predicted temperatures during the actual mission
are 19.3 K (35 °F) lower than the check valve temperature at the time
of the observed sticking. This, combined with the fact that momentary
sticking would have little possibility of degrading the mission, resulted
in the decision to not change the flight check valves.
52
All other components functioned as expected. All specification require-
ments were satisfied. Reliability of the propulsion subsystem was demon-
strated and all interfacing equipment, such as pyro, thermal, structure,
and support equipment, operated and functionally interfaced satisfactorily.
53
JPL Quarterly Technical Review Volume 1, Number 2 July 1971
Prediction of Lipid Uptake by Prosthetic Heart
¥ai¥e Poppets From Solubility Parameters
J. Moacanin and D. D. Lawson
Propulsion Division
H. P. Chin, E. C. Harrison, and D. H. Blankenhorn
University of Southern California
Most prosthetic heart valves currently implanted consist of a silicone rub-
ber poppet situated within a metallic cage. Recent reports indicate that
gradual deterioration of the poppet can occur and lead to serious valve mal-
function. Physical changes (variance) observed in recovered prostheses in-
clude discoloration, swelling, and cracking. A major cause of variance is
believed to be Mpid accumulation. This article presents an assessment of the
solubility of lipids in silicone rubber and other commonly used poppet ma-
terials. The analysis is based on solubiHty parameter theory that is based on
principles derived from thermodynamic considerations. The results of this
analysis predict that highly polar compounds, such as phospholipids or pro-
teins, should not be present in silicone rubber poppets, which is in agree-
ment with observations.
Introduction
Most prosliietic heart valves currently implanted consist of a silicone
rubber poppet situated within a metallic cage. Recently, reports have
indicated that gradual deterioration of the poppet can occur and lead to
serious valve malfunction (References 1-6). Physical changes (variance)
observed in prostheses recovered at autopsy or surgery include dis-
coloration, swelling, and cracking; these may be accompanied by altera-
tions in resiliency and specific gravity (References 1, 2, 4, 7, and 8).
A major cause of variance is believed to be lipid accumulation. Several
laboratories have reported that all blood lipids are found in implanted
valves, and occur in roughly the proportions usually found in human
plasma (References 3, 6, 9, and 10). In our recent studies, however, no
phospholipids or lipoproteins were found in any of the silicone poppets
that were assayed, while the other lipids occurred in widely varying
54
proportions (Reference 11). These results strongly suggested that lipid
infiltration is selective and that it may be influenced by the poppet
material.
This article deals with an assessment of the solubility of lipids in
silicone rubber and other commonly used poppet materials. The analysis
is based on solubility parameter theory that is based on principles derived
from thermodynamic considerations. The results of this analysis predict
that highly polar compounds, such as phospholipids or proteins, should
not be present in silicone rubber poppets, in agreement with observations.
Solubility Parameters for Poppet Materials and Lipids
In general, solubility, or miseibility, of two substances is to be expected
if there is a decrease in the free energy of mixing, viz.,
Inasmuch as the entropy of mixing ASmix is always positive (i.e.,
— TASmix < 0), the enthalpy of mixing AH^ix will virtually determine
solubility. The latter term for non-polar substances is positive and its
magnitude is proportional to the difference of the respective solubility
parameters 8 (i.e., square root of the cohesive energy density):
AHmix ~ (Si ~ 82)-
Thus, the closer the solubility parameter values, the smaller the AH,aix
will be and, consequently, the greater the decrease in AF^ij (References
12 and 13). For polar substances and those with strong tendency for
hydrogen bonding, the definitions are somewhat tenuous. B[owever, semi-
empirical correlations are possible nevertheless. It follows from the above
considerations that a lipid will dissolve in the poppet polymer material
if the respective values are close to each other. Equal 8 values, of course,
will favor solubility most. However, mutual miseibility will exist for a
range of values in the vicinity of the polymer solubility parameter Sp.
This range will depend in general on the particular polymer, but as a
rule of thumb solubility will be likely for lipids whose solubility param-
eters Sj are in the range Sj = Sj, ± 2. Inasmuch as the solubility parameter
is a measure of intermolecular forces, it defines a number of molecular
characteristics besides solubiHty. Consequently, there are a variety of
methods to determine its value. Heats of vaporization data are commonly
used for compounds which can be volatilized, whereas for polymers 8
is usually determined indirectly from swelling measurements. For this
work, literature data were used when available (Reference 14). However,
for lipids such information could not be found. For these, estimates were
made using semi-empirical correlations between the solubility parameter
and refractive index (Reference 15).
55
Table 1 shows 8 values for silicone rubber and other polymeric mate-
rials that are being used for valve poppets, M^hereas Table 2 shows values
for a variety of lipids.
Table 1. Solubility parameters for poppet materials (References 14 and 16)
Material
Repeat unit , , (calories/cm^)'''"
g/cm^
Poly ( tetrafluoroethylene )
Poly ( dimethylsiloxane )
-CFj-CFj- 2.3-2.4
CH,
— Si— O—
CH,
1.13
6.2
7.3-7.6
Poly (ethylene), high density
-CHj-CHo-
CH3
0.99
7.9-8.4
Poly ( propylene )
1
-CH-CH^-
0.90-
■0.94
8.2
Poly (ethylene terephthalate )
CeH^-COO-
1
COOCH^CH^-
CH,
1 ^
1.46
9.7-10.7
Poly ( methyltrifluoropropylsiloxane )
1
-Si-O-
1
C,H,CF3
1.4
8.5-11.0
Poly ( formaldehyde ) , crystalline
-CHj— 0—
1.50
10.2-11.0
Discussion and Analysis
Most of the available information on the efiFect of blood on valve
materials pertains to poly(dimethylsiloxane) elastomer, because most
valves currently implanted have poppets made from this material. This
elastomer contains about 20% silica filler. However, the powder, being
crystalline and dispersed in the elastomer matrix, is very impermeable
and is rather inaccessible to blood constituents. Thus, lipid uptake must
be controlled by the properties of the elastomeric matrix, which has a
solubihty parameter 8 of about 7.5.
Examination of Table 2 shows that 8 values for lipids fall in two groups:
for the weakly polar lipids, such as cholesteryl esters, triglycerides, and
cholesterol, S is about 9; whereas for the more polar phospholipids, 8 is
in excess of 16. Likewise, solubility parameters for proteins are again
high, i.e., 8 > 18. It is apparent that 8 for the first group is less than 2
units from that for the silicone elastomer and, consequently, well within
the range necessary for miscibility. On the other hand, both phospholipids
56
Table 2. Solubility parameters of possible blood lipids estimated from
refractive index data (Reference 15)
Lipids ( calories/cm3 ) ''
Cholesterol and esters:
Cholesteryl palmitate 8.4
Cholesteryl oleate 8.4
Cholesteryl stearate 8.4
Cholesterol 8.9
Triglycerides, a-glycerol ether esters and
fatty acids ( tripahnitin, tristearin, selachyl
dioleate, oleic acid, stearic acid) 8.0 to 8.3
Lipid soluble vitamins 8.6 to 10.9
Hydrocarbon lipids (isoprene based and
related alcohols) 8.2 to 8.5
Lipid bases (phosphorous and nitrogenous
materials) >16
Proteins > 18
Water 23
and proteins are far outside this range and therefore are insoluble. These
considerations provide a straightforward explanation for our observations
on recovered silicone rubber valve poppets (Reference 11), which showed
the presence of the first group of lipids and absence of both phospholipids
and proteins in poppets after implantation.
It has been reported that the extent of the vulcanization procedure
affects Hpid uptake (Reference 9). Vulcanization should not have a signif-
icant effect on 8, whereas it may greatly affect the crosslink density and
the sol fraction, i.e., amount of soluble siHcone. For given S, the maximum
(i.e., equilibrium) extent of swelling depends on these two factors
(Reference 17). In general, a decrease in crossHnk density and increase
in sol content (both likely consequences of insufficient vulcanization) will
increase the tendency to swell, or, in other words, favor lipid uptake. A
similar effect may result from chemical degradation caused by excessive
heating during vulcanization.
There is little information on variance in poppets made from other
materials. We have examined recently two poly(formaldehyde) poppets
which were implanted for rather short times. The results are preliminary
but it was interesting to note that even though there appeared to be little
foreign matter, some organic phosphorus was detected in one of the
poppets. The 8 value of near 11 for poly(formaldehyde) makes this result
plausible, but it is still sufficiently far from 16, the value for phosphoHpids,
to expect significant infiltration.
57
For the iuorosilicone elastomer we were able to arrive only at a
range for 8. Calculations gave a low value, whereas solubility experiments
(Reference 18) favor higher values. The higher value also seems to sup-
port the much lower lipid uptake for this elastomer as compared to
sihcone (Reference 9). Fluorosilicones would therefore appear to be
promising. But their undesirably high density precludes their use in
conventional configurations because for proper functioning the overall
poppet density must approximate that of blood. Fluorocarbons have low
S, and their density is very high. Hydrocarbons such as poly(ethylene)
and poly (propylene) do not have a favorable S. However, their density
is acceptable, and the highly crystalline forms of these polymers should
be more impervious to lipids than silicone.
The presence of certain lipids and the absence of phospholipids and
protein from silicone elastomer poppets is thus explained from considera-
tions of solubility properties. However, the mechanism by which these
hpids reach and infiltrate the poppet remains unknown. Lipids are present
in plasma as spherical lipoprotein complexes that vary in size from a few
hundred to perhaps 5000 A and contain from about 1 to as much as
50% protein. The physico-chemical properties of lipoproteins appear
to be dominated by the protein moiety, which suggests that their surface
must be covered by protein. When the protein content is insufficient to
form a monomolecular surface layer, it is believed that then the surface
consists of a mixed protein-phospholipid layer, the latter being oriented
with their charged groups at the surface (see, for example, References 19
and 20).
The silicone surface, like any foreign body in contact with blood,
becomes covered with a protein layer. Inasmuch as lipid components
exhibit considerable equilibration and exchange among the difl:erent
lipoprotein classes (Reference 20), it is likely that they would behave
similarly with respect to the protein layer on the silicone. Once on the
surface, their solubility, which is higher in silicone than in plasma, will
provide the necessary driving potential for permeation into the elastomer.
The importance of the blood flow to lipid uptake is suggested by the
fact that most known cases of poppet variance are for the aortic valve;
the blood flow velocity through this valve is the highest. The importance
of the flow profile to the rate of collision with a surface has been analyzed
in detail for the case of platelet deposition (Reference 21). Also, high
shear forces would tend to deform lipoproteins and consequently increase
the surface area, with the possible destruction of the continuity of the
protein layer, thus favoring lipid deposition upon collision with the
polymer surface. The fact that in vitro tests using lipid mixtures could not
duplicate the extent of in vivo uptake (Reference 6) suggests that surface
wetting by proteins and/or phospholipids is necessary for spreading of
lipids at the surface. The importance of spreading at the surface could
58
be tested by studying in vitro the effect of various emulsifying and
emulsion-breaking agents on lipid uptake.
Acknowledgment
The authors thank R. F. Landel and J. D. Ingham, JPL, for their
comments and suggestions regarding this study.
References
1. Starr, A., Pierie, W. R., Raible, D. A., Edwards, M. L., Siposs, C. G.,
and Hancock, W. D., Circulation, Vol. 33, Supplement I, p. 1-115,
1966.
2. Laforet, E. G., New Eng. }. Med., Vol. 276, p. 1025, 1967.
3. Pierie, W. R., Hancock, W. D., Koorajian, S., and Starr, A., Ann. N. I.
Acad. ScL, Vol. 146, p. 345, 1968.
4. Roberts, W. C., and Morrow, A. G., Am. J. Cardiol, Vol. 22, p. 614,
1968.
5. Lee, S. J. K., Zaragoza, A. J., Callaghan, J. C., Couves, C. M., and
Sterns, L. P., Circulation, Vol. 41, p. 479, 1970.
6. McHenry, M. M., Smeloff, E. A., Fong, W. Y., Miller, G. E., Jr., and
Ryan, P. M., /. Thorac. Cardiovasc. Surg., Vol. 59, p. 413, 1970.
7. Bonnabeau, R. C., and Lillehei, C. W., /. Thorac. Cardiovasc. Surg.,
Vol. 56, p. 258, 1968.
8. Hameed, K., Ashfaq, S., and Waugh, D. O. W., Arch. Paihol, Vol 86,
p. 520, 1968.
9. Carmen, R., and Kahn, P., /. Assoc. Adv. Med. Instr., Vol, 314,
p. 14, 1969.
10. Noiret, R., Penther, P., Bensaid, J., Beaumont, J. L., and Lenegre, J.,
/. Athero. Res., Vol. 8, p. 975, 1968.
11. Chin, H. P., Harrison, E. C, Blankenhorn, D. H., and Moacaiiin, J.,
Circulation, Vol. 43, Supplement I, p. 1-51, May 1971.
12. Hildebrand, J. H., and Scott, R. L., The Solubility of Nonelectrolytes,
3rd Edition. Reinhold Publishing Co., New York, 1950.
13. Gardon, J. L., "Cohesive Energy Density," in Encyclopedia of
Polymer Science and Technology, Vol. 3, p. 844. Interscience Pub-
hshers. Inc., John Wiley & Sons, Inc., New York, 1965.
14. Burrell, H., and Immergut, B., "SolubiUty Parameter Values," in
Polymer Handbook. Edited by J. Brandrup and E. H. Immergut.
Interscience Publishers, Inc., John Wiley & Sons, Inc., New York, 1966.
59
References (contd)
15. Lawson, D. D., and Ingham, J., Nature, Vol. 223, p. 614, 1969.
16. Lewis, O. G., Physical Constants of Linear Homopolymers. Springer-
Verlag, New York, 1968.
17. Fiory, P, J., Principles of Polymer Chemistry, Chapter XIII. Cornell
University Press, Ithaca, N. Y., 1953.
18. Lewis, F. M., Rubber Chem. Technol, Vol. 35, p. 1222, 1962.
19. HasMin, S. A., Felch, W. C, and Van ItalHe, T. B., "Lipid Metabo-
lism," in Handbook of Physiology, Circulation, Chapter 34. Edited by
W. F. Hamilton and P. Dow. American Physiological Society,
Washington, D. C, 1963.
20. Cornwell, D. G., "Lipoproteins," in Lipids and Lipidoses, pp. 168-189.
Edited by G. Schettler. Springer- Verlag, New York, 1967.
21. Friedman, L. I., Liem, H., Grakowski, E. F., Leonare, E. F., and
McCord, C. W., Trans. Am. Soc. Arti. Int. Org., Vol. 16, p. 63, 1970.
60
JPL Quarterly Technical Review Volume 1, Number 2 July 1971
Resequencing of the Structural Stiffness Matrix
to Improve Computational Efficiency
R. Levy
Telecommunications Division
Improved computational elRciency and reduction in core storage require-
ments in large-capacity structural-analysis computer programs are achieved
by taking advantage of the typical sparseness in the stiffness matrix. In many
cases, the favorable effects can be enhanced by resequencing the intercon-
necting terms of the stiffness matrix. This produces a relatively large empty
region that can be bypassed and a relatively small, compact region that is
moved into the core for computations.
In the past, the goal of resequencing has been to minimize the stiffness
matrix bandwidth. A favorable alternative resequencing procedure that has
the goal of reducing the matrix wavefront is described in this article. Com-
parisons are supplied to show the relative compactness that can be achieved
for practical structural models with wavefront sequencing and with bandwidth
sequencing. Examples show that wavefront sequencing can produce a savings
in tlie time required for subsequent decomposition of the stiffness matrix.
Introduction
Conventional finite-element analysis of structures is typically imple-
mented by any of the several currently available computer program
packages that perform matrix interpretive analysis. When the structure
to be analyzed entails many degrees of freedom, it becomes important
to develop the analytical model to fit efficiently within the computer
program capacity and to avoid excessive computation time for processing.
Ground-based radar antenna structures in the 26-m and larger classes are
practical examples from a wide range of structures that contain 1000 or
more degrees of freedom for which judicious modeling can provide
substantial computational benefits.
Large-capacity computer programs for structural analysis operate most
efficiently when the computational procedure is formulated to capitalize
on the typical sparseness of the structural stiffness matrix. Sparseness is
61
used to advantage by confining the computational operations to a com-
pact region densely populated with non-zero coefiBcients and by omitting
operations for the empty region in which the coefBcients are zero. Conse-
quently, it is often desirable to reorder a given stiffness matrix to make
the region for computations as compact as possible and to make the
empty region as large as possible. Traditionally, the compactness of
the stiffness matrix has been measured by the matrix bandwidth, but an
apparently more efficient equation-solving approach has been formulated
to perform the computations within the region delineated by the matrix
wavefront (Reference 1). The wavefront approach is attractive because
the maximum wavefront is often considerably less than the maximum
bandwidth, and it can never be greater.
The purpose of resequencing for an analytical model of a particular
structure is to minimize the number of degrees of freedom that determine
the maximum of the bandwidth or the wavefront of the stiffness matrix.
Frequently, the number of degrees of freedom per node is approximately
the same for all nodes. Therefore, it is reasonable to perform resequenc-
ing on the basis of the nodes and nodal connectivity, which is consider-
ably simpler than resequencing on the basis of degrees of freedom and
stiffness matrix connectivity. Algorithms of Rosen (Reference 2), Akyuz
and Utku (Reference 3), and Cuthill and McKee (Reference 4) were
designed to reorder nodes for bandwidth reduction. An algorithm to be
described here has been found effective for wavefront reduction. A recent
independent development by King (Reference 5), although described dif-
ferently, appears to be related to the present method.
Resequencing procedures, either for bandwidth or wavefront reduction,
do not ensure achievement of the optimal sequence. Results could be
considered acceptable if there is an improvement from an initial sequenc-
ing in a local optimum sense, rather than convergence to an absolute
minimum in a global sense. For this reason, it is sometimes useful to
perform, resequencing several times, with each cycle starting from a
different initial sequence. This provides the opportunity to select the
most favorable of the several local minimums that will be developed
from the various cycles.
Wavefront Counting
The wavefront at a row of the nodal connectivity matrix is the number
of active columns that follow the diagonal element; a column becomes
active at the row containing the first entry for that column, and it remains
active until that column is absorbed into the diagonal of the connectivity
matrix. As shown in Figure 1, wavefront counting is accomplished by
drawing heavy vertical lines for each column, beginning at the row at
which the column becomes active and ending at the diagonal. To obtain
the wavefront at each row, it is necessary only to count the heavy lines
crossing each row.
62
(a) EXAMPLE STRUaURE
(b) NODAL CONNECTIVITY MATRIX
Figure 1. Wavefront counting example
Alternatively, the wavefront at any row can be computed as equal to
the wavefront at the preceding row, plus the number of new columns
that become active. If the column corresponding to the row is currently
in the wavefront, then the wavefront is reduced by one. The subtraction
is made to account for columns that leave the wavefront by virtue of
reaching the diagonal. This method of wavefront counting is explained
for the rows of Figure la as follows:
Row 1: The wavefront is 4, because columns 6-9 become active at this
row and the wavefront at the non-existent preceding row is defined to be 0.
Row 2: Columns 3 and 5 become active; therefore, the wavefront is
2 + 4 = 6.
Row 3: Column 4 is added to the active list; because Column 3 was in
the wavefront, 1 is subtracted. Therefore, the wavefront is 6 + 1 — 1 = 6.
63
Rows 4-9: All columns have been activated (matrix has filled), and no
new columns can enter the wavefront. Therefore, at each row 1 is sub-
tracted from the preceding wavefront, since one column always reaches
the diagonal and leaves the wavefront.
The isolated colimin to the right of the connectivity matrix in Figure lb
gives the wavefront at the row. The maximum wavefront is 6, which
occurs at both the second and third rows. It will be shown that this can
be reduced by resequencing.
Wavefront Sequencing
A resequencing approach that is recommended here for its conceptual
simplicity can be called a "minimum growth" method. That is, assuming
that resequencing has already been used to identify the nodes that will
constitute the new first i nodes, the node to be selected as the new
{i + l)th node is the one for which the wavefront at the (i + l)th node
will represent the smallest increase with respect to the wavefront at the
ith node. In accordance with the alternative method just described for
wavefront counting, the increase can be a positive integer, zero, or nega-
tive unity. Very often, any one of several nodes will give the same mini-
mum wavefront increase for the (i + l)th node, and, when this happens,
the first node encountered is chosen. This tends to make the new
sequencing as close as possible to the original. The question remains, of
course, as to how to choose the node to be first in the new sequence. The
choice could be based upon one of the following alternatives:
(1) Choose the node that v^dU give the minimum wavefront for the first
row. This is equivalent to choosing the node with the minimum
number of connections. Break ties by picking the first node en-
countered.
(2) When the connectivity matrix involves n nodes, perform resequenc-
ing n times, picking each node in turn to be the first. At the end,
select the most favorable of the n sets of resequences. This method
is feasible if the number of nodes is not excessive.
(3) Perform resequencing k (where fc < n) times. Each time, pick at
random the node that is to be first. This procedure is suggested if
n is very large; nevertheless, more than one cycle of resequencing
should be tested for possible improvements.
(4) Assign one particular node to be the first in accordance with prior
inspection and reasoning.
The resequencing operations can be conveniently organized in a
tableau format for manual execution. This format employs the original
nodal connectivity matrix and a new table listing the change in wave-
front for each possible selection of the next node to be placed in the new
64
sequence. Tableau resequencing will be demonstrated for the structure
of Figure 1. Figure 2 shows the progressive changes (hea^/y lines) in the
combined tableau as each next node is selected to be placed within
the new sequence. For clarity, the figure is subdivided into the stages
associated with selecting one successively ascending node at a time. The
general procedure that is employed repetitively for selection of the suc-
cessive nodes is described below.
Wavefront Change Table Operations for Figure 2
Step 1: Enter the number of the new node that is about to be selected
in the new sequence heading list.
Step 2: Count the number of new connections at each ro^v. This is equal
to the sum of the entries in the connectivity matrix that do not occur at
columns already in the wavefront. The columns that are in the wave-
front are identified by vertical lines previously drawn through these
columns. The change in wavefront at each row is the sum of the new
connections. The change is reduced by one if the row is already in the
wavefront. Enter the change in wavefront in the column of the node to
be selected and opposite the associated row.
Step 3: Select the smallest change in wavefront from the column of
wavefront changes (first occurrence in case of ties). Circle the row entry
and draw a horizontal line across the wavefront change table. This is the
new row to be placed in the sequence. Add the wavefront change to
the preceding wavefront and enter the value at the space provided at the
bottom of the table.
Connectivity Matrix Operations for Figure 2
Step 1: Strike the column of the node just selected (a double line used
in Figure 2). Enter the new sequence number at the bottom of this
column in the space provided.
Step 2: Strike the row of the node just selected.
Step 3: Strike all unstruck columns that have connections in this row.
Additional Notes on Figure 2
Stage 1: The first node is selected with the objective of minimum wave-
front in the first row of the new sequence. Original node 2 is the first one
encountered with the minimum number of 3 connections. Original node 2
becomes the new first node, the wavefront at the new first row of the
connectivity matrix is 3, and columns 3, 5, and 7 of the connectivity
matrix become activated.
65
y. /AVEFRONT CHANGE TABLE NODAL CONNECTIVITY MATRIX
(STAGE 1)
NEW SEQUENCE
}
T
6
7
8
9
4
LU
:3:
u
i
O
3
3
'",
3
<
z
4
o
4
o
4
4
2 3 4 5 6 7
w
1
2
/
n
a
4
^
5
<r
6
z
V
8
9
WAVEFRONT
NEW SEQUENCE
X
X
X
X
<-
—
—
■A-
"-
x|
X
X
X
X
X
xl
X
X
X
X
X
X
X >{\
X
X
X
X
X
X
X
X
X
X
NEW SEQUENCE
(STAGE 2)
1 |2 1 1 1 1 1 1 1
4
3
X
ifc
3
:o
i&
3
1
3
1
4
2
4
2
4
2
4
4
3KI 1 1 1 M 1 1
1 2
3 4 >
3
6
7
8 9
1
1
X
X
X X
2
X--^-
A
3
— -X--
X
4
X _X
X
5
X
X
X
6
X
X
X
X
7
X X
X
X
8
X
K
X
X
9
X
X
X
X
h |2M 1 1 1 1 1
WAVEFRONT
NEW SEQUENCE
(STAGE 3)
2 3
in
J_
2
3
4
5
6
7
8
9
4
3
2
UJ
;3;
Z.
3
h
l»
i
3
1
;o:
0*
lyi
3
1
<
7
4
2
2
O
4
2
1
4
2
1
4
4
2
NEW SEQUENCE
1 2 3 4 5 6 7
|4 |4|
X
X
>(
T
.
X
~ X -
y
:><.
-
X
....'J~-
■x.
*
X
X
X
X
x"
X
X
X X
X
X
X >
>
c
>
<
X
X
X
X
WAVEFRONT
NEW SEQUENCE
Figure 2. Tableau resequencing example
66
WAVEFRONT CHANGE TABLE NODAL CONNECTIVITY MATRIX
(STAGE 4)
NEW SEQUENCE
2 3 4
I
2
3
4
5
6
2_
8
9
4
3
2
1
UJ
»
U
*
/.
3
:o
9,
*
3
1
;o^
m
3
1
:o)
_)
*
1
4
2
2
1
o
4
2
1
1
o
4
2
1
4
4
2
|3444 1
WAVEFRONT
NEW SEQUENCE
||2]345 1
1 ^
k
X
i
-■-■X--
k-
X--
,
-
,
,^
X----
X
X
X
X
X X
X
X
X X
X
X
X
X X
X
1 2| 3 4 I
NEW SEQUENCE
(STAGE 5)
I
2
3
4
_5_
_6_
7
8
9
4
3
2
1
:o)
*
■X
^
3
b)
3
1
'o)
3
1
>;
^
*
4
2
2
1
4
2
2
1
4
2
1
4
4
2
1 2 3 4 5 6
7
8
?
<-
■X
■X-
■^]
Ji
— X--
-
X-
3 - -X-
-
^\
5 - -X--
-x X
6 X
X ij
X
x|
7|^ X
>(
X
^1-- +
t ■---T
X
x|
'iL....
.A...JL
X
1
3 4 4 4 4
WAVEFRONT
NEW SEQUENCE
Figure 2 (contd)
Stage 2: Original node 3 causes columns 4 and 8 to become activated,
but node 3 has been activated previously; thus, the net increase in wave-
front is only one. Original node 3 becomes the new second node. Columns
4 and 8 are added to the active list, and column 3 leaves the wavefront.
Stage 3: Original node 4 activates column 9, but there is no net in-
crease in wavefront because column 4 was in the wavefront. Original
node 4 becomes the new third node, and column 4 leaves the wavefront.
Stage 4: Original node 5 activates column 6, but there is no net increase
in wavefront because column 5 was in the wavefront. Original node 5
becomes the new fourth node, and column 5 leaves the wavefront.
Stage 5: Original node 1 does not activate any additional columns, but
there is no net decrease in wavefront because column 1 was not on the
active list. Original node 1 becomes the new fifth node.
67
At the completion of stage 5, there are no remaining colimms to be
activated, and the wavefront has filled the connectivity matrix. The
remaining nodes can be added to the new sequence in arbitrary order,
and the veavefront will decrease by unity at each successive stage.
Results and Conclusions
Tableau resequencing can be performed without difficulty for matrices
with orders of 20 to 30. When the order becomes much larger, the
tableau becomes cumbersome, and it is advisable to perform resequenc-
ing by computer. A program has been written to automate the procedure
by performing essentially the same operations as those for executing the
tableau. The largest model for which the program has been used to date
has a connectivity matrix with over 500 nodes. In one test of the program
for this model, the initial sequencing was developed by inspection and
study of the connectivity. The maximum wavefront was 43. One rese-
quencing computer cycle reduced the initial maximum wavefront to 30.
In another test, the initial sequencing was scrambled at random, which
produced a maximum wavefront of 92. One computer cycle reduced this
to 40. As the result of six additional computer cycles, the maximum
wavefront was reduced to 27; in these, the starting node for each cycle
was chosen at random.
On the UNI VAC 1108 Exec-8 computer, the computation time for this
structure averaged about 15 s/cycle. For a structure with 75 nodes, the
program averaged more than 2 cycles/s. The computation time per cycle
varies considerably, depending upon how quickly the connectivity matrix
fills or upon the number of nodes processed before it can be determined
that the current cycle is to be aborted because there will be no reduction
of an existing maximum wavefront.
Table 1 shows some additional comparisons for resequencing tests to
reduce either bandwidth or wavefront. These tests were performed for
Table 1. Effects of resequencing on bandwidth and wavefront^
Component type
Nodes
Initial size
Size after resequencing
Bandwidth Wavefront Bandwidth Wavefront
Antenna pedestal
56
40
Quadripod
66
41
Coarse grid reflector
83
73
Azimuth— elevation
466
200
reflector
Polar reflector
506
—
20
18
30
52
92
23
16
24
75
11
8
12
29
28
^Bandwidth sequencing metliod described in Reference 2; wavefront sequenc-
ing method described in tliis article.
68
the analytical models of structural components used on ground-based
radar antenna systems. The table shows that, after sequencing, the wave-
front tends to be less than half of the bandwidth, which can provide
definite computational advantages in subsequent analysis. The savings in
computation time depends to some extent on the type of analytical prob-
lem to be solved and the eflSciency of the approach used to process the
stiffness matrices. For statics problems, comparisons have shown that
about 20% savings in stiffness matrix decomposition time could be
achieved by using wavefront sequencing instead of bandwidth sequencing.
In eigenvalue problems, the possible savings appears to be considerably
greater. Table 2 shows a few cases from Table 1 where the comparable
decomposition times were available for both types of sequencing.
Table 2. Stiffness matrix decomposition times
Component type
Problem type
Decomposition time, s
Bandwidth
sequencing
Wavefront
sequencing
Coarse grid reflector
Azimuth-elevation reflector
Statics
Statics
Eigenvalue
10.4
260.1
3604.5
7.5
215,2
635.4
The experience with the computer program indicates that minimum
growth sequencing is effective, rapid, and capable of producing worth-
while economies. The savings occurs in the reduction or elimination of
lengthy effort to study a particular structural model for the purpose
of generating an acceptable sequencing pattern, as well as in the reduc-
tion of computation time as the result of processing a relatively compact
stiffness matrix.
References
1. Melosh, R. J., and Bamford, R. M., "Efficient Solution of Load-
Deflection Equations," /. Struct. Div., Proc. ASCE, Vol. 95, No. ST4,
pp. 661-676, Apr. 1969.
2. Rosen, R., "Matrix Bandwidth Minimization," Proceedings of the 23rd
National Conference of the ACM, p. 585. Brandon/Systems Press, Inc.,
New Jersey, 1968.
3. Akyuz, F. A., and Utku, S., "An Automatic Node-Relabeling Scheme
For Bandwidth Minimization of Stiffness Matrices," AIAA J., Vol. 6,
No. 4, pp. 728-730, Apr. 1968.
4. Cuthill, E., and McKee, S., Reducing the Bandwidth of Sparse Sym-
metric Matrices, Applied Mathematics Laboratory Technical Note
69
References (contd)
AML-40-69. Naval Ship Research and Development Center, Washing-
ton, D.C., June 1969.
5. King, I. R., "An Automatic Reordering Scheme For Simultaneous
Equations Derived From Network Systems," Int. J. Numer. Meth.
Eng., Vol. 2, pp. 523-533, 1970.
70
JPL Quarterly Technical Review Volume 1, Number 2 July 1971
On the Statistical Distribution of Spacecral
Maximum Structural Response
J.-N. Yang
Engineering IViechanics Division
In most aerospace engineering applications, the finite number of flight
data accumulated in the past is not sufficient to characterize Donstationary
random excitations resulting from each flight event, such as booster engine
ignition or burnout. In this article, a direct statistical analysis of spacecraft
maximum structural response is performed and the spacecraft structural
rehability is obtained. It is found that the Gumbel Type I asymptotic
distribution of maximum values provides a reasonably good statistical model
for spacecraft maximum structural responses. The current approach makes
it possible to perform the reliability-based optimum design of spacecraft
structures.
Introduction
Flight data taken on a number of past flights indicate that major
spacecraft excitations and responses resulting from booster engine
ignition or booster engine shutdown are nonstationary random processes
(e.g., References 1 and 2). These excitations not only are highly transient
but may also produce some of the most severe spacecraft vibrations in
the entire mission. A typical example taken from Reference 2 is given in
Figure 1 in v^^hich three sample functions of nonstationary random pro-
cesses applied at the base of the launch vehicle are given. In Figure 1,
two random forcing processes resulting from two booster engines have
been converted into a resultant thrust process F(t) and a bending
moment process M{t).
For the reliability prediction and the design of spacecraft structures,
the rigorous random vibration approach, unfortunately, suffers from a
number of difficulties as follows:
(1) The number of sample functions accumulated from past flights for
the same type of booster engine is not sufficient for the statistical
characterizations of F{t) and M{t), as well as their correlations.
Thus far, 27 samples are available.
71
Figure 1. Typical sample function of nonstationary random excitation
(from Reference 2)
(2) Because of the complexity of the entire space vehicle structure
and the excessive computational cost involved, the redesign of the
spacecraft structure is usually made separately from the vehicle, us-
ing the resulting six random acceleration processes, gi(t),i — 1,2,- • -,6,
at the spacecraft/boost vehicle (S/BV) interface as input excitations
for approximation (Reference 1). Therefore, even if the number of
samples is sufficient to characterize random excitations F{t) and M(t),
the computer storage space required for all the digitized data of
covariance functions Kg^g. (t^, to), or generalized spectra S,jj,. (wi, wo),
of all the six random processes, gi (t), i = 1,2, • • • ,6, may easily
exceed the computer capacity. Furthermore, the numerical opera-
tions involved in computing the statistics of responses and response
derivatives, such as covariance functions, are quite involved. Pre-
liminary investigation indicates that the cost of spacecraft redesign
(many cycles of redesign) becomes intolerable when the rigorous
random vibration approach is employed.
(3) The prediction of structural reliability or failure, such as the first
excursion probability, under nonstationary random excitations is
still in the primitive stage. Hence, the final reliability figure usually
72
involves two kinds of approximations: (a) the ap]3roximation of
known random processes, such as gaussian processes, to the actual
processes, and (b) the approximation made in estimating the
rehabihty from the response statistics.
It is due to these theoretical, as well as practical, difBciilties that other
possible approaches appear to be highly desirable. In fact, some attempts
have been made from the viewpoint of deterministic analysis. The premise
of deterministic analysis approaches, so far, is to obtain an upper bound
of the maximum response under a specified class of excitations. In this
connection, the upper bound of the maximum structural response based
on the excitation energy (Reference 3), the response envelope in the
frequency domain analysis (References 1 and 4), and the response
envelope in the time domain analysis (Reference 5) should be mentioned.
Although the foregoing deterministic analyses provide useful information
for structural design, there are two inherent discrepancies; (1) the upper
bound obtained may be too high and there is no indication of how
conservative it may be, and (2) the estimated upper bound is not associ-
ated with any probability statement. Since the excitations are random
processes, the probability statement is important in design.
It has been realized that the source of randomness in excitations is
due to the fact that the properties of rocket motors are associated with
considerable statistical variation. Thus, a sample of a rocket motor
generates a sample of random excitations which, in turn, produces a
sample value of maximum response at certain points of the spacecraft.
Hence, there is a one-to-one correspondence between the maximum
spacecraft response and the property of the rocket motor. Since the
underlying physical process describing how the ignition or shutdown
of the random rocket motor is related to the random excitation processes
is not clear, the assumption of certain types of nonstationary random
processes, such as random processes obtained by passing a modulated
short noise through a filter (Reference 1), is difficult to be justified. It,
therefore, appears that a direct statistical analysis of the spacecraft
maximum response may be a reasonable approach when 27 sample
functions are available.
Statistical Analysis of Maximum Response
The advantages of the direct statistical analysis of spacecraft maximum
responses can be summarized as follows; (1) the cost of analysis and
redesign is within practical limitation, (2) the accuracy of the reliability
estimate increases as the number of samples increase, and (3) it admits
to a reliability -based optimum design of spacecraft sti-uctures.
Let the structural system of the space vehicle be characterized by
a linear time invariant operator L, which relates the spacecraft stress
73
response vector Y(f), consisting of component Yft(*), k = l,2,---, to the
excitation vector process X(t) through the following equation:
L[Y(*)] = X{t) (1)
where X{t) consists of the thrust process F{t) and the bending moment
process M{t) at the base of the launch vehicle, i.e.,
X(t) = [F(t) M{t)y
V/hen the redesign of spacecraft structures is separated from the space
vehicle, L represents the spacecraft characteristics and
is the acceleration vector process at the S/BV interface.
The stress response vector Y{t) can be written as
Yit)= rHt-T)X{r)dr (2)
Ylt) = i- /"" H(a>)X(a>)e-i<"*c^» (3)
ill which b(t) and M{w) are, respectively, the impulse response matrix
and the frequency response matrix or transfer matrix. Both h{t) and M{oi)
are Fourier transform pairs, and they are functions of natural frequencies,
modes, generalized masses, and dampings of the structure (e.g., Reference
1). X(w) is the Fourier transform of X(f). The solution of Equation 2 is
referred to as the time domain analysis, while the solution of Equation
3 is referred to as the frequency domain analysis.
Let X^(t), X'((o), and Y|(<-) represent the /th samples of X(*), X{m), and
Y;c(t), respectively, where Y]c{t) is the spacecraft stress response at point
k. The absolute maximum, Z, of Yje{t) for * > is a random variable
whose /th sample value Zj follows from Equations 2 and 3 as
Zj = max I Yl{t) | = max
= TT— max
r Kit - r)X'{r) dr (4a)
'H;,(co)X''(»)e-^'"*tL (4b)
where H7;(&)) and hj,{t) are the kth row of H(«>) and h{t), respectively.
74
Then, rearrange Z,-, / = 1,2, •••, 27, in an ascending order such that
Zi <Z2 •■• <Z27.
Some investigations (Reference 6) indicate that when the excitation
X(*) is nonstationary gaussian, the distribution of the peaks or troughs
within a time interval [0,T] is approximately the Weibuli distribution,
which is a distribution of exponential type. Furthermore, large peaks or
troughs, being of particular interest in design, are approximately inde-
pendent; and if the number of peaks or troughs in the response history
approaches infinity, the asymtotic distribution of the maximum response
Z can be shown (References 6 and 7) to follow the Gnmbel Type I
asymptotic distribution of maximum values as follows:
F2(a:) = Pr[Z < x] — exp{ — exp [ — o-(x — [i)]}
cr>0, — oo<X<oo,— 00<11<00 (5)
where F^(x) is the distribution function of the maximum stress response
Z, and or and fx are distribution parameters.
If the samples Zi,Z2, • • •, Z,? follow the distribution of Equation 5, they
should be scattered around a straight line when plotted on Gumbei
extreme-value probability paper. The empirical distribution function
Fm(Z;c) for the sample values Zi,Z2, •••,Z27 can be established as
F^Zk) = {k- 0.5)/n (6)
where n is the total number of samples and is equal to 27 herein.
The first quadrant of a preliminary design of a spacecraft is shown
schematically in Figure 2 (four quadrants are symmetrical). Sample values
of maximum stresses Zi,Z2, • • • , Z,? in each structural member, due to
27 samples of excitation vector X(f) at the base of the launch vehicle
during the stage 1 shutdown, are computed. These sample values are
then plotted on both the Gumbei extreme-value probability paper and
the cumulative probability paper; five of these typical plots are given in
Figure 3. In Figure 3, members 1 and 2 are capsule members, members 3
and 4 are spacecraft members, and member 5 is a member supporting the
fuel tank (see Figure 2). All the plots indicate that the Gumbei Type I
asymptotic distribution of maximum values is a reasonably good model.
Results of the Kolmogorov-Smimov test (e.g.. Reference 8) indicate that
the hypothesis that the sample data of maximum stress responses in each
member follow the distribution of Equation 5 can be accepted at least at
the 20% level of significance.
Other distribution functions, such as normal, lognormal, Weibull, and
gamma, etc., have been tried; it was found that the plots associated with
75
Figure 2. Schematic configuration of a spacecraft
these distributions exhibit a clear departure from linearity, and the asso-
ciated Kolmogorov-Smirnov statistics are higher than those associated
with the distribution of Equation 5. This is an indication that Equation 5
may be the best to fit the samples of maximum stress response. Indeed,
the Gumbel Type I asymptotic distribution of maximum values (Equa-
tion 5) is a logical choice for the maximum response in approximation,
although the conditions for the distribution that peaks are independent
and that the number of peaks approaches infinity are not satisfied. In
fact, some investigators (Reference 9) in earthquake engineering have
shown that Equation 5 provides a reasonable statistical model for max-
imum structure response due to earthquakes, where the conditions for
the distribution are clearly violated. Gumbel has also shown problems
(Reference 7) where the distribution conditions are not satisfied but where
the distribution of Equation 5 is a good model.
The probability of first excursion failure pu of the kth. structural member
follows from Equation 5 as
(1 - exp {-exp [ — <Tf:(x -lift)]}) /ft(x) dx
(7)
where f],{x) is the probabihty density of the ultimate strength of the kth
member, and aj, and fiji are the associated distribution parameters which
76
4.0
1 1
1 1 U->
MEMBER 1
^^ o
2.0
-
^^o
0.0
ESTIMATED GUMBEL
TYPE I DISTRIBUTION
? n
d^
SAMPLE DISTRIBUTION
1 1 1
1.5 1.6 1.7 1.8 1.9 2.0
1.0
0.8
0.6
0.4
0.2
0.0
1
- MEMBER 1
^^ -
: /i
SAMPLE -
/
DISTR!- ^
/
BUTION
V
estimated
gumble'
TYPE I 1
"/
DISTPxl- ■"-
-I 1
BUT ED -
_l ! t
.8 2.0
4.0
1 1 1
_MEMBER2
1 1 !
..r<^^^^
t> -
2.0
^
9-^^^
-
0.0
- ^
-
-2.0
^ ,
I 1 1
1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8
4.0
1 1 1 1
^MEMBERS
1 j 1 1
1
^o -
2.0
^
j,--''^
-
0.0
- ^^
-
2.0
r, , ,
1 1 1 1
1
3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2 4.3
2.0
-2.0
2.7 2.8 2.9 3.0
3.2 3.3 3.4
4.0
1 1 1
_MEMBER 5
' '
1 1
1 ^
2.0
«^
O-""'^
'O
-
0.0
~ .^^"^
-
7.0
< , ,
1 1
1 1
1
9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.S 13.0 13.5
MAXIMUM STRESS, 10'^ N/cm^
9.0 10.0 n .0 12.0 13. c
Figure 3. Distribution of maximum stress responsie
77
can easily be estimated from Figure 3. The material used for each struc-
tural member of the spacecraft (Figure 2) is aluminum with a mean
ultimate strength of 20.68 X lO'' N/cm^. Results of this analysis indicate
that the probability of failure of each member is negligibly small except
member 5, which has a probabihty of failure 0.45 X 10"", when the statis-
tical dispersioa of the ultimate strength of aluminum is negligible.
It follows from Equation 4 that the computation of 27 samples of
maximum stress response Z,-, / = 1,2, ■••,27, for each structural member
requires neither heavy computational effort nor excessive storage in com-
puter. In fact, using the fast Fourier transform, TLj can easily be computed
(Equation 4b). Therefore, the cost involved in computing the structural
reliability, Equation 7, as well as redesign of spacecraft structures, is
within practical limitation.
While it is not difficult to compute structural reliability, one can pro-
ceed to perform the reliability-based optimum design of spacecraft struc-
tures (e.g., Reference 10), and minimize the structural weight subject to
the constraint that the overall probability of failure of the spacecraft p;
should be less than certain value p^. The feasibility of incorporating the
notion of reliability in optimum design is another advantage of the cur-
rent approach. It should be mentioned that much research work remains
to be done before the rigorous nonstationary random vibration approach
can be incorporated in optimum structural design.
Conclusion
Under nonstationary random excitations resulting from booster engine
shutdown, a direct statistical analysis of spacecraft maximum responses is
performed and the spacecraft structural reliability is obtained. It is found
that the Gumbel Type I asymptotic distribution of maximum values
provides a reasonably good statistical model for spacecraft maximum
responses. The current approach makes it possible to perform the
reliability- based optimum design of spacecraft structures.
Acknowledgment
The author gratefully acknowledges valuable information and discus-
sions by B. K. Wada and J. Garba of the Jet Propulsion Laboratory.
References
I. Marx, M. H., et al, "Evaluation of Techniques for Estimating Titan
III-C Flight Loads," paper presented at the AIAA 3rd Communica-
tion Satellite Systems Conference, Los Angeles, Calif., Apr. 6-8, 1970.
78
References (contd)
2. Titan Launch Vehicle — Stage I Thrust Transient Data Book,
MCR-70-8. Martin Marietta Corp. Aerospace Group, Denver, Colo.,
Jan. 1970.
3. Drenick, R. F., "On the Model-Free Design of a Seismic Structure,"
/. Eng. Mech. Div., Proc. ASCE, Vol. 96, No. EM4, pp. 483-493,
Aug. 1970.
4. Shinozuka, M., "Maximum Structural Response to Seismic Excita-
tions," /. Eng. Mech. Div., Proc. ASCE, Vol. 96, No. EMS, pp.
729-738, Oct. 1970.
5. Yang, J.-N., and Heer, E., "On Maximum Dynamic Response and
Proof Testing," Preprint 1372, presented at the ASCE Annual Meet-
ing on Structural Engineering, Baltimore, Md., Apr. 19-23, 1971, to
appear in /. Eng. Mech. Div., Proc. ASCE, Aug. 1971.
6. Shinozuka, M., and Yang, J.-N., "Peak Structural Response to Non-
stationary Random Excitation," Proceedings of the AIAA/ASME
12th Structural, Structural Dynamics and Materials Conference, Ana-
heim, Calif., Apr. 19-21, 1971.
7. Gumbel, E. J., Statistics of Extremes. Columbia University Press,
New York, 1958.
8. Lindgren, B. W., Statistical Theory. The Macmillan Company, New
York, 1962.
9. Wirsching, P. H., and Yao, J. T. P., "Distribution of Response to
Simulated Earthquakes," J. Eng. Mech. Div., Proc. ASCE, Vol. 96,
No. EM4, pp. 515-519, Aug. 1970.
10. Heer, E., and Yang, J.-N., "Structural Optimization Based on Fracture
Mechanics and ReHability Criteria," AIAA J., Vol. 8, No. 4, pp. 621-
628, Apr. 1971.
79
JPL Quarterly Technical Review Volume 1, Number 2 July 1971
Use of Pulsar Signals As Clocks
p. Reichiey, G. Downs, and G. Morris
Telecommunications Division
The pulses of energy from pulsars are regarded as ticks from a clock. By
comparing this pulsar clock with an earth-based atomic clock, several varia-
tions in the pulsar clock's frequency are noted. The major effect is due to
the motion of the atomic clock in relation to the pulsar clock and contains
information on the pulsar's position, elements of the earth's orbit, and solar
relativistic effects. Another effect is the slowly varying frequency of the
pulsar clock and contains information on the physics of the pulsar. In this
article, the measurements of these effects and their present and future appli-
cations are discussed.
Introduction
One of the remarkable properties of pulsars is the emission of periodic
pulses of energy. The periods of the known pulsars vary from 0.033 to
4. s. The periods are also slowly increasing with a typical value of
200 ns/yr. If these pulses are regarded as ticks of a clock, this pulsar
clock can be calibrated with great accuracy.
Shortly after the discovery of pulsars, a program was started in order
to see how well these pulsar clocks could be calibrated. The Venus
Deep Space Station (DSS 13) at Goldstone is an ideal environment in
which to conduct the measurements. The low-noise maser receiver and
the high-rate sampling ability of the station are ideally suited to the
measurements, The S-band operating frequency also minimizes charged-
particle effects on the received pulse train.
The observations of the arrival times of the pulses are made using a
26-m parabolic reflector at a frequency of 2388 MHz. The atomic clock
used to record the time-of-arrivals is a cesium standard, which is com-
pared monthly with the master clock at the National Bureau of Standards.
80
The observational technique has been described elsewhere (References 1
and 2) and will not be described here. The sampling resolution of the
pulses is typically on the order of 100 ixs.
The determination of the arrival time for each pulse is accomplished
by correlation techniques. The signal-to-noise ratio for the pulses is
improved by coherently adding at least 500 pulses. The pulse is then
correlated with a template which approximates the pulse shape. The
determination of the arrival time has been described more fully in Ref-
erences 1 and 2. Typically, they have a standard deviation on the order
of 100 lis.
An initial application of the pulsar clock was the synchronization of
earth-based clocks. The application of this technique to the Deep Space
Network seemed attractive since only an antenna to receive and a corre-
lator are needed, i.e., a passive measurement. The technique is not
presently competitive with the moon-bounce technique, due to the present
limitation on sampling resolution and the noise on the pulses. Work is
currently being done to develop a technique to sample the pulses faster.
The determination of the pulsar's positions and period characteristics
has proved of value to the scientific community. Several groups of optical
observers have used our positions and periods to try to detect pulsars
optically. The period characteristics have been used by the scientific
community to try to explain some of the physics of pulsars.
An attempt has also been made to measure the sun's gravitational red
shift. The magnitude of the effect is easily within the measurement accu-
racy but has so far eluded detection due to correlation problems. A tech-
nique to eliminate these correlations and make a definitive measurement
is currently being worked on.
With improved sampling resolution, elements of the earth's orbit can
be improved. At present most of the measurable parameters are better
measured by planetary radar. The parameter of the earth's orbit that can
best be measured by pulsar clocks is the orientation of the orbit with
respect to the celestial sphere. These measurements are currently made
using a combination of optical and radar measurements.
Problem Formulation
The period characteristics of the ticks from the pulsar clocks, as ob-
served at Goldstone, are different from those of the emitted ticks, Of
interest are the differences, as well as the period characteristics, of the
emitted ticks. The differences between the emitted and received period
81
characteristics can all be attributed to the motion of Goldstone in the
ineitial frame of the solar system (within measm-ement accuracy).
The inertial frame used for the calculations is a right ascension-
decHnation system for the epoch 1950.0 centered at the barycenter of the
solar system. The ephemeris used to describe the motion of the geocenter
about the barycenter is JPL ephemeris DE-69 (Reference 3). The motion
of Goldstone about the geocenter, the conversion from ET (ephemeris
time) to UTC (universal time coordinated), and the reduction to the epoch
1950.0 were computed by means of standard equations using parameters
developed at JPL (Reference 4).
To remove the effects of Goldstone's motion, the arrival times of the
ticks were reduced to the barycenter of the inertial frame. The line
element used to make the reduction is the Robertson isotropic line ele-
ment which is consistent with DE-69. This allows us to account for
relativistic eflFects on the arrival times, such as delay in the solar gravita-
tional field and the red shift of the atomic clock as it moves in the solar
gravitational field.
The pulsar's angular position is needed in order to make the reduction
to the barycenter. Changes in the period due to changes in the relative
distance between the barycenter and the pulsar are indistinguishable
from the emitted period for motion on the order of galactic rotation
(Reference 2). This is not true if the distance varies in a rapid (in the
galactic sense) manner such as if the pulsar were in orbit. Proper motion
and distance can also be detected in a manner similar to optical tech-
niques.
The period characteristics are described by means of a polynomial
that is equivalent to a Taylor series expansion of the period. The period
is given as a function of time from some initial epoch. This form of
representation is convenient since other models can be related to our
model by simply comparing the derivatives.
A mathematical model has been constructed which includes all of the
above-mentioned effects as free parameters. This model is used to predict
the time-of-arrival of ticks at the barycenter of the inertial frame. These
predictions are compared with the observations and the model is then
differentially corrected by least-squares techniques.
Currently, 20 pulsars are being observed on a regular basis. Solutions
of the parameter sets for 12 pulsars have been obtained (References 2
and 5), and work is continuing on the remaining 8, as well as on the first
12 for improved solutions. Since the major solar system effects on the
arrival times of the ticks are tied to the earth's motion about the sun, a
year's worth of data is typically required to obtain a minimal correlation
solution.
82
Results
Specific numerical values for the results that were obtained in this
study are given in References 2 and 5. Our main interest here will be
with the precision of the results and the limits of this precision. Our
discussion wiU be limited to only typical results and not for any one
pulsar.
Regarding position determination, definitive results have been ob-
tained for angular position only. After a year's worth of data, the typical
limitation is the accuracy of the ephemeris of 0.1 seconds of arc in right
ascension and declination. This limitation is due to the uncertainty in
reducing the data to the inertial frame. The typical relative uncertainty
is on the order of a few hundredths of a second of arc. Bounds have
been determined for proper motion and distance (Reference 6). A
typical lower bound for the distance is on the order of 50 light years and
a typical upper bound on proper motion is on the order of 0.1 seconds of
arc per year. These measurements are limited by the noise on the
arrival-time data.
The period characteristics of most pulsars are described quite well by
a simple polynomial, i.e., a constant plus a linear term. The constant
term corresponds to the period at some epoch and the linear term
corresponds to the rate of change of the period. The uncertainty in the
period determinations is typically a few parts in 10" (a few hundredths
of a nanosecond). The uncertainty in the rate of change determinations
is typically a few parts in 10^ (~10-" seconds per second). The accuracy
in determining period characteristics is limited by noise on the time-of-
arrival data and the length of the data span. There are two pulsars for
which the linear model does not describe their period characteristics.
They are discussed in the next section.
Definitive results have not been obtained in our attempts to measure
relativistic effects. A highly correlated measurement of the gravitational
red shift of the sun was obtained (Reference 7), which agrees with
theory to within a few percent. The limitation on the measurement was
the use of data from one pulsar only. By using as many pulsars as
possible, the correlation of the result could be reduced significantly. An
attempt was made to measure the time delay of the ticks of the pulsar
clock as they passed through the sun's gravitational field. However, the
accuracy in arrival time needed to make the measurement was not
achieved. The basic Hmitation was noise on the data.
Discussion
The noise on the data has been blamed for the basic limitation in the
majority of the measurements discussed in the previous section. The noise
83
can be thought of as having two components, discrete and random. The
random component is due to the random noise that is inherent in the
received signal. This causes random errors in the measurements of
the pulse arrival times. For pulsars with stronger signals, the discrete
component of measurement error shows up. Since there is a limit to the
speed at which the pulses can be sampled, the error then becomes de-
pendent on the length of time between samples.
Currently, work is being done on methods in which to reduce the noise.
The obvious solution to the discrete component is to sample at a rate fast
enough such that the noise is indeed random. Therefore, equipment
which will sample at a faster rate is being designed and constructed.
The random noise can also be reduced somewhat. As mentioned in the
introduction, the arrival times are estimated by correlating an approxi-
mate pulse shape with the data. These estimates can be improved by
correlating with the true pulse shape. By adding all the pulses for a
particular pulsar and using this as the "true" pulse shape, it is hoped that
this improvement can be attained. Just such a technique is currently
being worked on.
As mentioned in the last section, the limitation to angular position
determination was the accuracy of the ephemeris, mainly the rate of
precession. If the measurement accuracy of the data can be improved,
then this limitation would disappear for then the rate of precession can
be solved for.
The length of the data span was mentioned as the limitation in the
determination of period characteristics. The solution to this, of course, is
to take data for a long time. But this, then, opens the door to other
unknowns which must be solved for. It has been observed that two
pulsars do not have a period described by a linear period model. These
two pulsars are described by higher-order polynomials. It is predicted
that other pulsars will also exhibit this behavior. The measurement of
the quadratic term, or second derivative, is important in determining the
radiation process of pulsars. Our estimates show (Reference 2) that for
some of the pulsars which are being observed, this effect should be
observable after approximately 5 yr.
Another error source that will show up over a length of time is the
uncertainty in planetary masses. Since the inertial frame used in the data
reduction is solar system barycentric, it involves all the planetary masses.
If there is significant error in a planet's mass, this efFect will show itself
in a period of time roughly comparable to half of the planet's period of
revolution. Much care must be exercised in solving for these effects,
especially the longer period ones. Galactic rotation could contribute
similar effects. This means that measurements should be taken for at
least two periods of a particular planet's orbit before an attempt is made
to improve its mass determination.
84
As mentioned, there are two pulsars whose period characteristics are
not described by linear polynomials. A more accurate description would
be that they are not described by polynomials at all. The periods of the
Crab Nebula pxilsar and the Vela pulsar are not only not described by
polynomials but also exhibit discrete jumps in their periods (see, for
example. Reference 5). These effects are ideal for determining the physics
of the pulsars themselves but make them very unreliable as pulsar clocks.
These pulsars are believed to be much younger than other pulsars and
to be in an unstable state. All the other pulsars have exhibited stable
periods for the 3 yr that they have been under observation.
There are other applications of pulsars in determining the unknowns
of the galaxy and the solar system. The observation of dispersive effects
on the pulsar signals has yielded information on the electron content of
the interstellar medium. The observations of scintillations on the signals
has yielded information on the size and density of election clouds and
their movements. Some scintillation measurements have been made (Ref-
erence 8) and more are being planned.
It is concluded that the calibration of pulsar clocks is indeed a useful
concept, and that there is a wealth of knowledge that can be gleaned
in the process.
References
1. Downs, G. S., Morris, G. A., and Reichley, P. E., "Average Pulsar
Energies at Centimeter Wavelengths," Nature, Vol. 222, No. 5200,
pp. 1257-1258, June 28, 1969.
2. Reichley, P. E., Downs, G. S., and Morris, G. A., "Time-of-Arrival
Observations of Eleven Pulsars," Astrophys. /., Vol. 159, pp. L35-L40,
Jan. 1970.
3. O'Handley, D. A., Holdridge, D. B., Melbourne, W. G., and Mulhol-
land, J. D., JPL Development Ephemeris Number 69, Technical Report
32-1465. Jet Propulsion Laboratory, Pasadena, Calif., Dec. 15, 1969,
4. Melbourne, W. G., MulhoUand, J. D., Sjogren, W. L., and Sturms,
F. M., Jr., Constants and Related Information for Astrodynamic Cal-
culations, 1968, Technical Report 32-1306. Jet Propulsion Laboratory,
Pasadena, Calif., July 15, 1968.
5. Reichley, P. E., and Downs, G. S., "Observed Decrease in the Period
of Pulsar PSR 0833-45," Nature, Vol. 222, No. 5190, pp. 229-230,
Apr. 19, 1969.
6. Reichley, P. E., "Pulsar Astrometrics and Period Characteristics," Pro-
ceedings of International Symposium on Pulsars and High Energy
Activity in Supernovae Remnants, Accademia Naziortale de Lincei,
Rome, Dec. 1969.
S5
References (contd)
7. Reichley, P. E., "Tests of General Relativity Using Pulsars," Proceed-
ings of Conference on Experimental Tests of Gravitational Theories,
California Institute of Technology, Pasadena, Calif., Nov. 1970 (in
press).
8. Downs, G. S., and Reichley, P. E., "Observations of Interstellar Scin-
tillations of IPulsar Signals at 2388 MHz," Astrophys. ]., Vol, 163, pp.
L11-L16, Jan. 1, 1971.
86
JPL Quarterly Technical Review Volume 1, Number 2 July 1971
Characteristics of a Cigar Antenna
S. A. Brunstein and R. F. Thomas
Telecommunications Division
Dual-frequency propagation experiments will be performed using tlie Deep
Space Network 64-m antennas and the Mariner Venus-Mercury 1973 and
Viking orbiter 1975 spacecraft. For such experiments, the 64 -m antennas
must be capable of receiving and transmitting at S-band and simultaneously
receiving at X-band. One possible configuration involves placing an X-band
feed inside the S-band feed horn.
A cigar (metallic-disc-on-rod) antenna was investigated for this application
because this type of antenna is physically thin and would have minimal effect
on the radiation from the S-band feed horn. A cigar antenna design obtained
using new phase velocity data is described in this article. The new phase
velocity measurements were required when it was found that the available
published data for diso-on-rod structures were in error. The new measure-
ments and the experimental results obtained with the resulting design are
also described.
Introduction
Dual-frequency propagation experiments will be performed using the
Deep Space Network 64-m antennas and the Mariner Venus-Mercury
1973 and Viking orbiter 1975 spacecraft (Reference 1). For these experi-
ments, the 64-m anteimas must be capable of receiving and transmittlDg
at S-band and simultaneously receiving at X-band.
Several configurations are being investigated to implement this cap-
ability. One involves a coaxial feed in which an X-band radiator is placed
inside the S-band feed horn on the centerline. The obvious requirement
is that the X-band device must be diametrically small to avoid distortion
of the fields in the S-band horn. The X-band feed must also have a radia-
tion pattern that is very similar to that of the S-band feed (Reference 2)
in order to achieve essentially identical aperture efficiencies at both fre-
quencies.
87
Investigation of antenna types that could be used led to the class of
long, thin, endfire antennas typified by the polyrod (dielectric) antenna
(Reference 3, pp. 16-23). These antennas are slow-wave structures that
achieve their gain by length rather than by aperture size. Scale-model
experiments showed that this type of antenna of the approximate required
size could be placed in the S-band feed horn with negligible effect on
the radiation pattern. Specifically, it was decided to investigate a relatively
little known form known as the cigar or disc-on-rod antenna. This
antenna, essentially a metallic analogue to the polyrod antenna, was
chosen because of concern for the effect on S-band system noise tempera-
ture if a dielectric rod was introduced into the S-band horn. A cigar
antenna is shown in Figure 1.
■**>■•»=
"*^«,
Figure 1. Cigar antenna
General design criteria for lengths, phase velocities, etc., required to
achieve a given result with a slow-wave endfire antenna are thoroughly
discussed by Jasik in Reference 3. Jasik also discusses phase velocity as
a function of physical dimensions of disc-on-rod structures, based on the
work of Simon and Weill (Reference 4). Based on the material in
Reference 3, investigation of a cigar antenna was begun.
However, the initial results achieved with the cigar antenna did not
meet expectations. Since the general phase velocity design criteria had
been amply proven in polyrod antennas, the phase velocity data for the
disc-on-rod structures became suspect; thus, an experimental program
was undertaken to obtain new phase velocity measurements for these
structures .
Phase Velocity Measurements
Phase velocity measurements were performed by three diflFerent tech-
niques over a frequency range of 7-10 GHz. In all cases, the disc-on-rod
88
structure was fed from a circular X-band waveguide, excited by the
linearly polarized TEn mode. The inside diameter of the waveguide was
3.477 cm. The first disc of the disc-on-rod structure was located in the
waveguide aperture. No discs were inside the waveguide, but the support
rod extended several centimeters into the waveguide, and the disc-on-rod
structure was supported by two thin Micarta discs inside the waveguide.
The disc-on-rod structures had disc diameters ranging from 1.397 to
2.159 cm, with center-to-center spacings of 0.635, 0.953, and 1.270 cm.
Two support rod diameters were used: 0.635 and 0.953 cm. The discs
had a thickness of 0.0762 cm in all cases. Although difficulty was experi-
enced with spatial harmonics throughout the measurements, the results
were sufficiently conclusive to demonstrate that the data of Simon and
Weill are substantially in error.
Measurements were first performed by moving a large metal plate with
a hole for the cigar structure along the cigar and measuring the relative
phase of the reflected energy with a Hewlett-Packard network analyzer
to establish the wavelength on the cigar. The results of this measurement
appeared to disprove Simon and Weill, so further investigation was felt
to be in order.
The next technique used a small probe to measure the relative phase
along a cigar structure that was terminated into free space with a taper;
the last technique was identical, except that the cigar was terminated
into a block of microwave absorber.
All of the measurement techniques suffered from the usual problem
whereby the methods upset the fields sufficiently to affect the measure-
ments. The difficulty was especially acute when the velocities on the
structure approached the free-space velocity. Nevertheless, all three sets
of measurements showed substantial agreement, and the results were
quite different from those of Simon and Weill. The belief in the correct-
ness of the measurements is substantiated by the fact that the cigar
antenna designed from these data worked precisely as anticipated.
The results of the measurements are shown in Figure 2, along with the
curves of Simon and Weill. The parameter limits for which the results
are considered valid are shown on the figure. During the course of the
measurements, it was found that the phase velocities were reasonably
well-behaved until either the spacing of the discs or the diameter of the
support rod approached 0.25 wavelengths. At values greater than about
0.21 wavelengths, the data became quite erratic, and it appears that the
phase velocity is not a smooth function of physical diraensions above
this value. Values smaller than 0.15 wavelengths were not investigated,
nor were the effects of disc thickness.
The data shown by the points on Figure 2 did not justify more than
a single phase velocity curve. It appears that the disc spacing does not
89
0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40
(D - d)/\
Figure 2. Ratio of free-space wavelength to wavelength on the cigar
antenna as a function of normalized disc depth
significantly affect the phase velocity within the parameter limits shown.
Significant data could not be taken below (D — d)/X = 0.18 because of
the measurement problems previously indicated. Certainly, the assump-
tion of the j)oint at zero seems justified, but the curve between there and
the first data point must remain suspect.
Cigar Antenna Design
Using the general phase velocity criteria for a low-
slow-wave antenna of about 22-dB gain (Reference 3),
was designed. Some empirical manipulation of the disc
constant velocity section where the velocity is near the
was necessary to achieve the best results, indicating that
region of the phase velocity curve may indeed be in
certainly not grossly so.
sidelobe endfire
a cigar antenna
diameter in the
free-space value
the interpolated
error, although
The final design is shown in Figure 3. The waveguide inside diameter
in regions A through E is 3.477 cm; in region I, it is tapered linearly to
8.192 cm. This small flare was found to substantially reduce the wide-
angle radiation,. The diameter of the center conductor in region A is
linearly tapered from a point to 0.635 cm. The diameter in region B is
constant at this value. In region C, the diameter tapers linearly to 1.415
em. Region D is constant at this value, and region E has a diameter
of 1.080 cm. The center conductor dimensions were determined empiri-
cally such that a low voltage standing-wave ratio would be achieved.
The disc-on-rod structure begins at the right side of region F in
Figure 3. With the exception of the taper at the radiating end, it consists
entirely of discs of thickness 0.0762 cm, spaced 0.625 cm, on a rod of
90
Figure 3. Cigar antenna physical configuration
diameter 0.625 cm. The first disc at the right of region F has a diameter
of 1.704 cm. The disc diameter is tapered Hnearly over a length of
10.160 cm to a diameter of 1.549 cm and over a further distance of
45.72 cm to a diameter of 1.080 cm. This diameter is then held constant
over a length of 33.020 cm. The disc diameter is then linearly tapered
into the support rod over a distance of 3.810 cm. Region G has the
constant diameter of the support rod, and, in region H, the diameter is
linearly tapered to a point. The cigar is supported by foam plugs with
a dielectric constant of about 1.02.
Experimental Results
The antenna was fed with a linearly polarized TEu mode in the
circular waveguide, and radiation pattern and voltage standing-wave
ratio measurements were taken. Results were found to be good over
the range of 7-9 GHz.
A typical radiation pattern is shown in Figure 4. While only the
H-plane pattern is shown, the E and H planes are virtually identical over
the main lobe and very similar over the full sphere. In both planes,
radiation beyond an angle of 50 deg is more than 40 dB below the peak
of the beam, except near 7 GHz, where it is down about 35 dB.
Directivity and beam efficiency were computed by pattern integration
over the full sphere. While the directivity of 21.5 dB is significantly less
than the 22.5-dB measured gain of an X-band feed horn, it is shown in
Figure 5 that, at the edge of the Mars Deep Space Station antenna
subreflector (29-deg included angle), the same amount of energy is
included in the beam of the cigar as in the beam of the feed horn, and
that the beam efficiencies are quite similar over the entire subreflector.
This leads to the assumption that, while the beam shapes are difiFerent,
the antenna efficiency will be essentially the same with either feed.
91
'\
A
A
/\l
1
I
-180
-60 -30 30 60 -20
ANGLE FROM CIGAR ANTENNA BORESIGHT AXIS, deg
Figure 4. Relatiye amplitude and relative phase as functions of angle from the
cigar antenna boresight axis (typical of both E and H planes at 8500 MHz)
92
Figure 5. Fraction of the total radiated power contained
in a cone about the antenna boresight axis
93
It must be pointed out that no actual gain measurements have yet
been made with the cigar, and nothing is yet known of the possible
losses on the disc-on-rod structure. Integration o£ the X-band horn
pattern gave a directivity of 22.5 dB, in good agreement with measure-
ments. This gives confidence in the pattern integration technique, pro-
viding the radiator is virtually lossless.
Figure 6 shows the 10-dB bandwidth, phase center location, and voltage
standing-wave ratio of the cigar antenna as functions of frequency. Of
70
40
30
(b) DISTANCE OF ANTENNA PHASE
CENTER FROM FIRST (LARGEST)
DISC, cm
^^^
-^
.30
.20
1.10
.05
.00
(c) VOLTAGE STANDING-WAVE RATIO
AT WAVEGUIDE INPUT TO ANTENNA
/\
\
\
rx /
V/^
/^ V.
/
v.^
7.0
FREQUENCY, MHz
Figure 6. 10-dlB beamwidth, phase center location, and voltage
standing-wave ratio of cigar antenna as functions of frequency
94
particular interest is the virtual frequency independence of the beam-
width compared to the usual inverse frequency relationship demonsti-ated
by the curve for the feed horn. Unfortunately, the phase center is not
as well-behaved.
Conclusions
The phase velocity curves of Simon and Weill are in error. Using the
phase velocity curves generated experimentally, a cigar antenna can be
designed with good gain and sidelobe characteristics. If the losses on
the disc-on-rod structure are small, the cigar will make a good feed
device for cassegrain antennas or a good medium-gain lightweight
antenna for other applications.
References
1. Levy, G., Dickinson, R., and Stelzried, C, "S/X Band Experiment,"
in Supporting Research and Advanced Development, Space Programs
Summary 37-61, Vol. Ill, pp. 93-95. Jet Propulsion Laboratory, Pasa-
dena, Calif., Feb. 28, 1970.
2. Brunstein, S. A., "A New Wideband Feed Horn with Equal E and H
Plane Beamwidths and Suppressed Sidelobes," in The Deep Space
Network, Space Programs Summary 37-58, Vol. II, pp. 61-64. Jet
Propulsion Laboratory, Pasadena, Calif., July 31, 1969.
3. Jasik, Antenna Engineering Handbook, Chap. 16. McGraw-Hill Book
Company, Inc., New York, 1961.
4. Simon, J. C, and Weill, G., "A New Type of Endfire Antenna," Ann.
Radioelectricite, Vol. 8, p. 183, 1953 (in French).
95
JPL Quarterly Technical Review Volume 1, Number 2 July 1971
Jmprovements in Deep-Space Tracking
by Use of Third-Order Loops
R. C. Tausworthe
Telecommunications Division
Third-order phase-locked receivers have not yet found wide application in
deep-space communications systems because the second-order systems now
used have performed adequately on all past spacecraft missions. However, a
survey of the doppler profiles for future missions shows that an unaided
second-order loop may be unable to perform within reasonable error bounds.
This article discusses the characteristics of a simple third-order extension to
present second-order systems that wiU not only extend their doppler-tracking
capability, but will widen the pull-in range, decrease pull-in time, lower the
voltage-controlled oscillator noise detuning when no signal is present, and
lessen the susceptibility to voltage-controlled oscillator drift.
Introduction
Second-order phase-locked receivers, used both in spacecraft and in
ground tracking stations, have performed their function so satisfactorily
that, up until now, there has been little or no reason to consider the
installation of a more complicated system. Their performance character-
istics have become well-understood, analyzable, and easily optimized rela-
tive to almost any criterion in a straightforward, well-defined way. Their
capability to track incoming signals over a great range of signal levels
and doppler profiles and to maintain lock and coherence at very low
signal-to-noise ratios has become an accepted engineering fact.
As the more diiBcult deep space missions come into being, however,
there is a corresponding stringency of requirements placed on the track-
ing instrument, as well as corresponding need to reevaluate the best
ways of performing the tracking function technically, economically, and
operationally. The Mariner Mars 1971 orbital missions and the Pioneer F
Jupiter flyby mission, for example, have doppler rate profiles that may
cause up to 30-deg steady-state phase error in the unaided second-order
96
loops now implemented. Such stress in receivers decreases the efficiency
with which command or telemetry data are detected (by 1.25 dB at
30 deg), makes acquisition of lock difficult and faulty, and increases the
likelihood of cycle slipping and loss of lock.
The way to avoid these problems is clear: eliminate or diminish, the
offending loop stress. This can be done by widening the loop bandwidth,
by programming the uplink and downlink frequencies to correct these
effects, or by increasing the order of the tracking loop. Widening the
loop bandwidth increases loop noises; hence, it cannot be accepted as a
general solution for the diminution of loop stress. Programming the
uplink frequency and ground station local oscillator in accordance with
the predicted doppler profile is certainly a valid solution, but it is costly
to implement and introduces difficulty in reducing the two-way doppler
data for navigation purposes. It also may require accurate predicts
during critical phases of a mission where an a priori doppler profile is
uncertain.
A third-order loop, however, will track the actual phase deviations
presented to it without the need for accurate predicts. Raising the order
of the loop to three would thus seem to be an ideal, even if only partial,
solution because of its simplicity and possible economic factor.
The basic characteristics of third-order phase-tracking systems have
been known since the first works of Jaffee and Rechtin (Reference 1), but
these systems have not found wide application in the past due to vv-hat
seemed to be poor acquisition and stability characteristics. Design seemed
more complicated and was not well-understood. However, these potential
problems have been overcome to the extent that a loop of the third
order can now out-perform a second-order loop not only in its ability to
track a frequency ramp with practically zero phase error, but also in its
ability to acquire lock more quickly and from greater offsets. Even when
synthesized with imperfect integrators within the loop filter, the third-
order system will out-perform a perfect second-order system by orders-
of -magnitude improvement in steady-state phase error, lock-in time, and
pull-in range. One further advantage to the third-order system is that
there is less of a requirement for the long time constants dictated by the
high loop gains needed in the second-order loop to maintain small
tracking errors.
Other advantages are that the loop filter configuration is a simple
extension of presently mechanized loops, so required modification is
minor; the role of the receiver operator subsequent to lock is essentially
eliminated; several bandwidths are not needed to acquire rapidly; and
frequency drifts in the loop voltage-controlled oscillator (VCO) cause
essentially no degradation in performance. This last advantage may
97
remove the need to have the VCOs in ovens and thereby further extend
the usefulness of the system.
Third-Order Loop Synthesis
When minimizing the total transient distortion plus noise variance by
the Wiener filtering technique (Reference 1), one is led to the following
optimum loop iilter for tracking an input phase acceleration 6(t) = Aot-/2:
F{s) = -— +
Values are chosen so the parameter r = AKtI/t-^ is equal to 2. In usual
notation, A refers to the rms input signal ampUtude and K is the loop
gain. The first part of this filter resembles that used in the second-
order loop (Reference 2). Based on this resemblance, one may conceive
(References 3 and 4) a two-stage loop design: acquisition by the second-
order loop to avoid any of the problems that a third-order system out
of lock might supposedly have, and subsequent addition of the other
pole to remove loop stress. As will be shown, such a configuration is
particularly useful for unattended receivers; henceforth, it will be referred
to as a hybrid design.
However, perfect integrators are not usually practical, so modifications
are necessary. The loop filter to be considered in the remainder of this
article may be synthesized in many ways, three designs of which are
shown in Figure 1. These aU have the same transfer function,
n^) = T-T—: +
1 -I- ns (1 -I- ns) (8 + r^s)
With the same loop transfer function, the designs operate identically
once the loop is locked; they di£Fer in their lock-in transient behaviors,
however, because of the possibly different initial capacitor voltages. If
all C's are shorted at if — 0, they are again identical (within limits intro-
duced by hardware imperfections). However, when the loop is operating
as a hybrid, i.e., as second order {Co, or Cz and C3 shorted) during the
acquisition phase and third order (C2, or C^ and C3 released) after lock.
Circuit I exhibits a different transient phenomenon than do Circuits II
and III because of the placement of the capacitors.
In a Circuit I hybrid, the charge on Ci at the end of the acquisition
phase is related to the loop frequency mistuning, Oq = 27rAf. It causes
the transient shown in Figure 2 in the third-order loop, which, if too
large, can knock the loop irrecoverably out of lock. Such a characteristic
leads to the conclusion that Circuit I is not generally suitable for hybrid
loop design. Circuits II and III, however, exhibit no such transient away
from lock and thus make excellent hybrids.
98
CIRCUIT I: EXTENSION OF SECOND-ORDER
LOOP BY ADDITION OF ONE INTEGRATOR
SOUTION
AMPLIFIER
"3
ISOIT^TION
AMPLIFIER
HH
(I — ^A/v— <i
'2' '3
R,
CIRCUIT II; EXTENSION OF SECOND-ORDER
LOOP BY ADDITION OF TWO INTEGRATORS
>R, ISOUTiON
AMPLIFIER
€ -
- ^/-l
^r
(R, + R,
)C
R5C3
^2'
«2S
^3 =
R3C2
8 =
^3/^4
l< =
^2/^3
CIRCUIT III: NOT AN EXTENSION OF
USUAL SECOND-ORDER LOOP
,^h'
ISOLATION
AMPLIFIER
■^
e—
l<= ,/t_
Figure 1. Third-order loop filters
The two-sided noise bandwidth in the simplified, but usual, case
e = to/ti « 1 and 8 « 1 is given by
Wl
r /r -k + 1\
l^\ r-k )
99
c
-0.1
-0.3
^^
/
/
r = 2
« « 1
'
8 =
k = 0.5
---o.sstV^
3.42
1
10
TIMEtw,
20
Figure 2. Circuit I hybrid loop transient caused by final
lockup voltage on Ci
The parameter fc is the time-constant ratio rjr^. As compared with the
loop bandwidth formula of the second-order loop, the simplified expres-
sion above is only slightly increased in complexity, and, of course, the
two merge to the same result as fc — » 0.
The primary determining factors of Wi, are still t2 and r, just as in the
second-order loop. The phase error variances of any two loops due to
input noise are, of course, the same as long as their loop bandwidths
are the same.
Acquisition and Lock-In Behavior
The phase-plane technique, which is useful in visualizing the lock-in
behavior of second-order loops (Reference 5), does not readily extend the
same advantage to third-order systems, partly because there are three
initial conditions — phase, frequency, and frequency rate — needed to
specify a unique trajectory, and partly because this trajectory lies in a
three-dimensional, difficult-to-imagine, hyperplane. By analogy, however,
one still can visualize that, if there is a beat frequency between the
incoming sinusoid and the VCO, there will be a small dc voltage at the
detector output tending to force the loop toward lock. The extra integra-
tion in the loop accumulates this force, accelerating the loop toward lock.
There is thus an understandable reduction in the time required to reach
the zero-beat lock-in region, and there is a corresponding increase in the
loop piill-in-frequency range, as compared to that with a second-order
system.
100
If loop damping is not set properly, the great velocity acquired by the
loop phase and the momentum associated with the two integrations of
the error may carry the loop frequency error past the lock region, perhaps
out of lock so rapidly that recovery is not possible. Proper setting of the
system roots can reduce this velocity through the zero-beat region enough
to prevent frequency overshoot or irrecoverable loss of lock. In fact, if
the loop has no underdamped roots, there is no transit past the zero-beat
region.
The theory developed for computing the pull-in range of a second-
order loop is easily extended to account for effects in the third-order loop;
there is an enhancement in the acquisition range by approximately the
square root of the added integrator dc gain. In fact, experimental evi-
dence (Figure 3) verifies this formula exceedingly well aU the way out to
the point where IF filtering or minute equipment bias imperfections
begin to limit the loop pull-in.
f=0.05
1 1
SECOND-ORDER LOOP
1 e= 0.005
1 1
1 /"'
f
= 0.01
f=0.05
a=o.02
^
€= 3.05
8 =--3
!•
- — €=0.05
y^
, 1
8= O.I
y^
1
/
«= 3.01
1
y^
8= 3
1.
y^
£= 3.005
1
y
y^
8= 3
1
jl
/
^
^
i
'A
20
30
LOOP FREQUENCY OFFSET ilQ/27rW|_
Figure 3. Measured acquisition time as a function of loop
frequency offset (normalized axes)
101
Steady-State Errors
Due to imperfect integrations, there are steady-state phase errors that
build up because of the instantaneous frequency detuning and the rate
of change of this detuning. Compared with the corresponding expression
for a second-order loop, the steady-state error <^ss due to an instantaneous
frequency offset is reduced by a factor of about 8, and the error caused
by a frequency rate is diminished by a factor of about S + (e/k). Such a
comparison reflects the desirability not only of making e and S very small,
but also of keeping k as large as other factors will permit. Figure 4 de-
picts the steady-state phase errors that result from frequency offsets and
frequency rates.
Root Loci
For a given set of loop constants, the loop gain K or signal level A may
be varied and the position of the poles of the transfer function L{s)
plotted. Since r = AKt-Jti is proportional to both A and K, it may be
used as the independent variable. The system roots start at the poles of
F{s) at f = and finally terminate at the zeros of F(s). These loci take on
different characteristics, depending on the value of fc = tz/ts.
Th.e six loci illustrated in Figure 5 show, for various increasing k:
(a) When k > fc^ax, there are two underdamped (complex) and one
overdamped (real) roots for all r > rose-
(b) When k = fc^ax, there are two underdamped and one overdamped
roots for all r > r^sc except at r «i 3, at which point all three roots
become equal.
(c) When /c, < A: < fc^ax, there is a region where two roots pass from
underdamped to critically damped, to overdamped, to critically
damped, and finally to underdamped.
(d) At k = ko, the system roots are always critical or overdamped for
f > 3.375.
(e) The k < kg case is similar to the k — ko case, except there is a root
nearer the origin, indicating a more sluggish response when
j'c < fco.
(f ) When k = 0, the zero cancels the pole near the origin, producing
a second-order loop.
The cases illustrated in Figure 5b and 5d are of special interest. Fig-
ure 5b depicts the maximum value of k (i.e., fcmax) that can be used when
no underdamped roots are desired. In such a design, there is only one
fixed operating signal level (i.e., r = 3). Figure 5d shows the maximum
102
10
10
1
NORMALIZED STEADY-STATE
FREQUENCY-RATE PHASE
ERROR </.;j w^Ag
S=0.1 ^.——— — ■"'
^
0.05
Xy/
y
0.02 _.— —
CK0J_____
0.005 —
0.001 /
/^
V
8=0.1 /
/A .
/ n it; /
NORMALIZED STEAC
FREQUENCY-OFFS
ERROR 0^^W|_/ao
Y-STATE /
ET PHASE /
/ / /
/ 0.02 /
/ 0.01 /
/ O.DK /
/^
/ / /
-/ 0.00/ /
/ O.OOI /
/ 0.0005 /
^
/ / /
/ 0.0002 /
/ 0.0001 //
/ n nnnn=; /
/ /
/ / /
/ 0.00002 /^
^^ 0.00001
n-3
' = "2/^1
Figure 4. Normalized phase errors due to frequency offsets anc
frequency rates as functions of loop filter imperfections
103
r = 1/3 -
Figure 5. Root loci of the third-order loop as a function of r = AKtI/ti for
various values of the parameter k = t./ts
104
value of A: (i.e., ko) that can be used if no underdamped roots are desired
at any signal level above a design point producing r^ = 3.375.
To minimize the possibility that acquisition is faulty, it is necessary
that damping be critical or beyond; to minimize steady-state error once
lock is achieved, k should be as large as possible. These two conditions
are met in slightly different ways according to the type of signals to be
tracked. If the design is to be for signals of a fixed level, then k should
be set to kma^c and r should be set to produce critical damping at this
level (Figure 5b). If the design is to be for signals of various intensities,
then k should be made equal to k^ and r should be set for critical damp-
ing (Figure 5d) at the weakest expected signal level to ensure that the
roots are never underdamped.
The gain margin is the ratio r/r„s„ which is about 22 dB for variable
signal level designs, 19 dB for fixed signal level designs and 12 dB for
hybrid designs.
Effect of Internal and VCO Noise
The effect of VCO and other noises internal to the loop can be
modeled as an equivalent noise voltage, n„(t), appearing at the VCO
input. The form of the phase-error it causes greatly resembles the cor-
responding equation for second-order loops, but the phase error variance
is about 10 to 18% higher than that for the second-order case. Hence,
there is no relaxation in the requirement for spectral purity in the VCO
to be used. However, there are other effects in the VCO not well modeled
spectrally; one such effect is a steady drift in rest frequency due to some
change in the oscillator operating condition, such as temperature or bias
voltage. These appear to the loop error detector as slight alterations to
the frequency offset or rate of the incoming sinusoid. Such effects can
be analyzed as part of the loop overall transient. Because the third-order
loop minimizes the effect of such transients, the drift requirement on
VCOs may be greatly relaxed.
Noise-Detuning of the VCO (Out of Lock)
When acquisition begins with the loop filter capacitors having the
initial random charges as deposited in them by input noise prior to
application of signal, there are random voltages which deviate the VCO
from its rest frequency by perhaps 1/S times as far as that in a second-
order loop with the same loop gain K. This comparison is somewhat
unfair, as it fails to recognize the increased tracking capability of the
third-order system. To judge performance between second- and third-
order systems fairly, it is necessary to raise the gain of the second-order
loop by this same 1/8 to equate the static phase errors due to detuning.
(There will be little change in the second-order loop's ability to track
105
an acceleration, however.) The frequency wanderings of the second-
order system will then always exceed those of the third-order system
by at least a factor 1 + (e/fcS). When k8 is smaller than e — t^/ti, the
advantage is obvious.
Concluding Remarks
This summary article has indicated the tracking performance gains that
can be obtained by simple modifications or redesign of existing receivers.
The interested reader desiring more detail may consult Reference 6,
which develops the theoretical performance of practical third-order track-
ing systems; presents design methods and procedures by which they may
be synthesized; discusses hardware configuration and implementation
factors; and indicates, by actual observed data, that the design goals and
performance measures are as specified by the theory.
References
1. JafFee, R., and Rechtin, E., "Design and Performance of Phase-Lock
Loops Capable of Near-Optimum Performance Over a Wide Range
of Input Signal and Noise Levels," Trans. IRE, Vol. IT-1, pp. 66-76,
Mar. 1955.
2. Tausworthe, R. C, Theory and Practical Design of Phase-Locked
Pieceivers, Technical Report 32-819, Vol. I. Jet Propulsion Laboratory,
Pasadena, Calif., Feb. 15, 1966.
3. Tausworthe, R. C, "A Second/Third-Order Hybrid Phase-Locked
Receiver for Tracking Doppler Rates," in Deep Space Network
Progress Report for November-December 1970, Technical Report
32-1526, Vol. I, pp. 42-45. Jet Propulsion Laboratory, Pasadena, Calif.,
Feb. 15, 1971.
4. Gardner, F. M., Phaselock Techniques, pp. 12, 15, 22, 31, 50, 52, 72,
and 74. John Wiley and Sons, Inc., New York, 1966.
5. Viterbi, A. J., Principles of Coherent Communications, pp. 64-72.
McGraw-Hill Book Company, Inc., New York, 1966.
6. Tausworthe, R. C, and Crow, R. B., Practical Design of Third-Order
Phase-Locked Loops, JPL Internal Document 900-450. Jet Propulsion
Laboratory, Pasadena, Calif., Apr. 27, 1971.
106
JPL Quarterly Technical Review Volume 1, Number 2 July 1971
Nofi-orthogonal Reduridaiit Configurations
of Sirigle-Axis Strapped-Down Gyros
A. K. Bejczy
Guidance and Control Division
The functional reliability of the inertial reference unit of a three-axis
stabihzed spacecraft for long lifetime missions is of speciJic concern. Realiz-
ing the highly efBcient redundancy potential inherent to non-orthogonal
emplacements of more than three single-axis strapped-down gyros, and con-
sidering practical implementation and performance criteria, 45-deg skew-
sjonmetric six- and four-gyro configurations based on the geometry of a
regular octahedron are presented in this article. These configurations result
in optimum performance, exhibit unique simplicity in gyro output processing
requirements, allow high-density packaging, and require reasonable fabri-
cation and test procedures. The redundancy potential of an octahedron six-
array gyro configuration is twice as high as that of six gyros in an orthogonal
emplacement. An octahedron-based skew emplacement of four gyros can
provide minimum redundancy for the inertial reference unit, which, for an
orthogonal emplacement, could only be obtained by six gyros.
fntroductiofi
For three-axis stabilized spacecraft designed for long lifetime (8-12 yr)
missions, the functional reliability of the inertial reference unit (IRU)
constructed of single-axis strapped-down gyros is of specific concern, since
the IRU has an irreplaceable functional assignment in the following
critical guidance and control system operations: celestial reference
acquisition, commanded turns, midcourse thrusting, planet encounters,
and celestial reference occupations or disturbances in the field-of-view of
the electro-optical attitude reference sensors. In addition to the critical
in-line functions, the IRU can also provide a significant backup for the
celestial attitude reference sensors in any phase of a mission.
Because of the very mechanism of attitude sensing through single-axis
strapped-down gyros, increasing the functional reliabilit>' of the IRU
must be sought not only on the component level of the single gyro instru-
ments, but also on the instrument level of the total IRU by employing a
107
redundant number of gyros. The physics of attitude sensing by single-
axis strapped-down gyros indicates two geometrically different ways to
employ a redundant number of gyros in the IRU: (1) paralleling two or
more gyros on each of the three orthogonal control axes of the spacecraft,
and (2) emplacing the sensitive axes of more than three gyros in a linearly
independent non-orthogonal configuration. Simple combinatorial calcula-
tions show that the redundant non-orthogonal gyro configurations are
much more efficient in increasing the functional reliability of the IRU
than are conventional redundancy techniques that simply parallel two or
more gyros on the spacecraft's three orthogonal control axes.
The highly eifective redundancy in full attitude reference inherent to
the non-orthogonal gyro configurations is physically based on the coupled
properties of attitude information obtainable through a linearly indepen-
dent non-orthogonal emplacement of the sensitive axes of a redundant
(n > 3) set of gyros. In such configurations, no one gyro is restricted to
replace the function of any specified gyro. For example, out of six gyros,
any three can fail without losing full attitude reference. This would
practically result in triple redundancy for attitude information on each
of the three orthogonal control axes of a three-axis stabilized spacecraft.
General Properties of Non-Orthogonal Gyro Configurations
For n > 3 single-axis strapped-down gyros in a non-orthogonal config-
uration, the total measurement vector in a compact vector-matrix notation
is
h = Aw (1)
or, in component form,
/ii = Ai^.to^ + At,jW,j + Ai^w- (la)
h-. = Ai^Wx + AoyWy + A2~w~ (lb)
where
h,t = An^^w^ + AnyWy + A„~w^ (In)
(hi,- ■ -Jiji)', an n-dimensional column vector representing the
outputs of the n gyros. Depending on the mode of operation of
the gyros, h is the angular rate or integrated rate (angular dis-
placement) measured by the 1,2, --^n gyros along the 1,2, ■•■,«.
gyro input-axis directions.
108
A = (Aij), an n-by-3 matrix of direction cosines relating the n gyro
input-axis orientations to the x,y,z (pitch, yaw, roll) orthogonal
control axes of the spacecraft (Figure 1).
w = {Wx,Wy,Wsy, a 3-dimensional column vector. Depending on the
mode of operation of the gyros, w represents the Aree angular
rates or integrated rates (angular displacement) along the x,y,z
spacecraft control axes.^
The quantities of interest for attitude control are Wx,Wy,w~, which now
are not measiued directly, but should be computed from Equations la-
in. Out of the n equations, only three are needed to determine the three
"unknowns" w^,Wy,w,. In fact, any group of three linearly independent
equations yield solutions for Wx,Wy,w~. (Linear independency means that
the input axes of the corresponding three gyros are not colinear or co-
planar.)
^For rate integrating gyros, the linear relationship given by Equation 1 will accu-
rately relate the measured angular increments hi to the x,y,z body-axis angular
increments Ww,tVp,w^ if the angular rates are low. This condition is satisfied for the
intended application.
INPUT-AXIS DIRECTION
FOR THE ";"TH gyro
h. = A. w + A. w + A. w
I IX X ty y iz z
A, =sin a. sin B.
.y 1 1
Figure 1. Orthogonal projections of one gyro in a
skew emplacement
109
Having a set of n linearly independent non-orthogonal gyro orientations,
there are nl/3! (n— 3)! possible combinations of three out of n gyro
measurements to determine ifj;,if j^tf^. That is, n = 4 gives 4, n — 5 gives
10, and n = 6 gives 20 different vi^ays to determine the three quantities of
interest. In contrast, an orthogonal emplacement of n = 6 gyros (parallel-
ing two gyros on each of the three orthogonal control axes of the space-
craft) yields only 8 ways to determine Wx,Wy,to^. Thus, in combinatorial
terms, six gyros in a linearly independent non-orthogonal emplacement
provide 2.5 times higher redundancy for full attitude reference than six
gyros in an orthogonal emplacement.
Selecting any three (hi,hj,hic) out of the n gyro measurements, the
computation of "equivalent" ■Wx,Wy,tv~ measurements requires the imple-
mentation of three equations of the following general form:
Wx = Bxihi + Bxjhj + Bxkhi: j
Wy — Byihi + Byjhj + Byl^K \ (2)
w^ = B^hi + B~jhj + B^TcK )
where Bi.i,---,B«ft are elements of the inverse of the 3-by-3 A'"''' sub-
matrix of A, the elements of which are the direction cosines of the
selected i,j,k gyro input-axis orientations. Clearly, each group of three
gyros has its own transform matrix B'"''''. It is noted that Bn,---,Bat are
precomputed constants determined by the fixed direction cosines
Aij.,--,Afe. The implementation of Equation 2 is depicted in Figure 2.
For low angiular rates and digital outputs of rate integrating gyros,
Figure 2 can be interpreted as follows : Process the hi,hj,h], gyro pulses as
they occur and count them in the Wa!,Wy,Wg adders according to the cor-
responding constant transform gains Bji,---,^^^.
Practical Criteria for Constructing Non-Orthogonal
Redundant Gyro Configurations
Theoretically, for a selected number n>3 of single-axis strapped-down
gyros, an unlimited variety of linearly independent non-orthogonal con-
figurations is possible. Practical considerations, however, will substan-
tially limit the possibilities of constructing appropriate configurations that
also match mission requirements and spacecraft constraints. The practical
construction criteria are as follows:
(1) Minimal transformation of the inherent (random and non-random)
instrument errors to the computed equivalent Wx,iVy,w^ measure-
ments. Assuming equal, independent, and normal random error
characteristics for each gyro, the random error transformation in
terms of the variance for the x axis is
-I = (Bi, + Bl, + Bl^)al (3)
110
<!>
<i>
V
-0-
Figure 2. Mechanization scheme for measurement transformation
where o-^ denotes the variance of a single gyro. The transformation
of the non-random instrument errors (drift, misalignment) is, in the
"worst case" and for the x axis, proportional to
I B^i I + I B.j I + I B.S I (4)
Clearly, similar expressions are valid for the y and z axes.
(2) Simple gyro output processing to obtain the equivalent Wx,w,j^tVg
measurements. This requires some cyclic symmetry for the values
of the transform gains. (For example, for six gyros in a linearly
independent non-orthogonal but otherwise unrestricted emplace-
ment, there exist 180 different transform gain values througli
which to obtain equivalent Wx,Wy,Wg measurements from the 20
three-gyro combinations.)
(3) Possible compact packaging for thermal control of the gyros and
economical use of spacecraft volume.
(4) Reasonable fabrication and test procedures.
References 1-5 represent the total reported works on non-orthogonal
gyro configurations. With the exception of Reference 2, they mainly con-
sider Criterion 1 and emphasize specific modes of operation or restrict
111
the configuration. Reference 1 considers only one four-gyro configuration
and one five-gyro configuration. Reference 2 considers two orthogonal
triads skewed relative to each other. References 3 and 4 describe the
dodecahedron six-array configuration of the Massachusetts Institute of
Technology. This work is the most elaborate and has reached the testing
phase; however, its main emphasis is on a self-contained failure monitor-
ing technique that can isolate any two failed gyros out of the six gyros,
and it assumes that the IRU operation starts with six gyros turned on.
Reference 5 considers mainly gyro arrays equally spaced on a 54.75-deg
cone. The reported works do not emphasize Criterion 2 in any specific
manner.
In this article, both Criteria 1 and 2 are basic concerns, and specific
attention is paid to Criteria 3 and 4.
45-deg Emplacement Symmetry for Four and Six Gyros
A 45-deg emplacement symmetry for four and six gyros offers great
advantages in processing gyro outputs to obtain the equivalent Wx,tOy,w~
measurements. Furthermore, such configurations provide optimal per-
formance regarding instrument error transformation, require reasonable
fabrication and test procedures, and can be emplaced in a high-density
package.
Six-Gyro Case
Let the six gyro input-axis directions, taken one by one and identified
with numbers 1 to 6, be oriented perpendicular to the opposite facing
parallel edges of a regular octahedron. Let this octahedron be emplaced
with its center at the origin of an x,y,z orthogonal reference system such
that the octahedron's opposite facing corners are fixed to the x,y,z axes
(Figure 3). The essential feature of this octahedron six-array emplacement
geometry is a skew symmetry: each one of the three datum planes contains
two gyro input axes aligned with 45-deg incUnation to the two reference
axes of the respective datum plane. Thus, each of the three reference axes
obtains symmetric (45-deg) projections from four of six gyro input-axis
directions. The direction cosine matrix of this configuration is then
Cyro
index
X
y
z
1
0.707
oriQi
2
-0.707
0.707
1 ^
0.707
0.707
4
0.707
-0.707
5
0.707
0.707
(5)
0.707 -0.707
112
The gyro output transformations into equivalent Wj:,Wy,w^ measure-
ments are listed in Table 1 for all 16 useful three-gyro combinations. The
four coplanar (hence, of no value) three-gyro combinations are also indi-
cated. Each 3-by-3 block in Table 1 should be interpreted in a vector-
matrix sense, having a mechanization scheme as depicted in general
terms in Figure 2. The numbers above each block identify three gyros
by their index numbers defined in Figure 3 and Equation 5. The values
inside each block identify the constant transform gains relating the
corresponding gyro outputs to the three {Wj;,w,j,w~) quantities of interest.
Table 1 clearly shows the unique advantage in measuremient processing
associated with the six-array configuration: All gyro outputs in all three-
gyro combinations liave one common scaling factor, c =- 0.707 [more
precisely, c = cos (45 deg) = 2'^]. The common scaling factor of the gyro
pulse signals can be considered as part of the instrument electronics of
the gyros or as a designed property of the Wx,Wy,w~ adders. Thus, having
scaled all gyro outputs by c, the elements in the sixteen 3-by-3 transform
matrices are 0,±1,±2. Moreover, there are many common rows and
columns in the 16 transform matrices given in Table 1. For example, in
Figure 3. Octahedron six-array gyro configuration (a = 45 deg)
113
Table I. Transform gains for the three-gyro combinations of the octahedron
six-array configuration (a'^^ = relative variance, c = 0.707)
1
2
3
<^',r
1
2
4
■r?.
1
2 5
"'iV
1
2 6 a\^
»^
c ■
— c
1.0
c -
-c
1.0
c
-c
1.0
c
-c 1.0
w,/ ^
^c
c
2.3
3.0
c
—c -
-2c
3.0
— c
— c 2c
3.0
c
c 2c 3.0
VJ„
c
c
1.0
c
c
1.0
c
c
1.0
c
c 1.0
1
3
4
<''.r
1
3
5
"l
1
3 6
ol
1
4 5 af.
2c
c -
— c -
-c
-c
1.0
1.0
3.0
c
— c
c
c -
c
— c
~c
c
c
1.5
1.5
1.5
Coplanar
combination
Coplanar
combination
1
4
6
<^l
1
5
6
-^L
2
3 4
"l
2
3 5 cTj,
•Wj.
c
c
c
1.5
2c
— c
c
3.0
c c
1.0
c
c
— c
— -
c
1.5
1.5
c
c
c
~c
1.0
1.0
2c
c — c
c c
1.0
3.0
Coplanar
combination
2
3
6
<'?.
2
4
5
O'L
2
4 6
0\r
2
5 6 ct;.
ti)»
—c
c ■
-c
1.5
— c
c
c
1.5
-2c
c -c 3.0
'W,j
Ws
c
c
c
c ■
c
— c
1.5
1.5
— c
c
— c
c
c
c
1.5
1.5
c
Coplanar
;ombination
c c 1.0
c -c 1.0
3
4
5
<'w
3
4
6
t^;.
3
5 6
<
4
5 6 o\.
Wi
c
c
1.0
c
c
1.0
2c
— c --C
3.0
2c
c c 3.0
Wy
c
—c
1.0
c
— c
1.0
c c
1.0
c c 1.0
w-
—c
c
2c
3.0
c
— c ■
-2c
3.0
c— c
1.0
c ~c 1.0
the 1,2,3; 1,2,4; 1,2,5; and 1,2,6 combinations, the transform gains for
w,: and w~ are unchanged, and only the polarities of the (numerically
unchanged) gains for Wy are varying. Clearly, these structural features
of the transform matrices imply very simple implementation.
The relative variances per reference axis (o-?^= al/a-l) due to the error
transformation of the skevi' geometry are also Hsted in Table 1 for each
three-gyro combination. As may be seen, in most of the cases there is no
error amplification; when error amplification does exist, the factor is
insignificantly small (1.5 and 3). Furthermore, even the worst-case non-
random error amplification factor is reasonably small, having a value
2.82. It is interesting to note that, for the three-gyro combinations of
the dodecahedron configuration (References 3 and 4), the highest relative
variance is 8.35, and the worst-case non-random error amplification factor
is 5. Thus, the octahedron six-array configuration tends to minimize the
maximum error amplification inherent to a skew gyro emplacement.
The six-array configuration also allows a high-density packaging, as
shown in Figure 4. Moreover, there is no difference between the packag-
114
EMPTY SPACE IN THE BOXES IS FOR
TWO ACCELEROMETERS AND THE
INSTRUMENT ELECTRONICS
ARROWS ON GYRO HOUSING
CYLINDERS INDICATE GYRO
INPUT-AXIS DIRECTIONS
Figure 4. Packaging of six and four gyros in
an octahedron-based emplacement
ing for the octahedron six-array configuration and that for an orthogonal
emplacement of six gyros, as is apparent from Figure 4. Furthermore, the
45-deg emplacement symmetry implies substantial advantages in the fab-
rication process (making alignment fixtures, cutting angles in a metal) and
in laboratory test procedures. In fact, system testing may be performed
on a single-axis test pad basis.
Four-Gyro Case
When only minimum redundancy is required for the lEU, it can be
provided by using four gyros in a non-orthogonal emplacement. (In an
orthogonal emplacement, minimum redundancy can only be obtained
by using six gyros.) Three different non-orthogonal emplacements of four
gyros can very easily be constructed from the octahedron sdx-array con-
figuration, retaining all the advantages of that configuration. The three
115
diflFerent non-orthogonal emplacements of four gyros will be equivalent
to having gyros 1,2,3,4; 1,2,5,6; or 3,4,5,6 (Figure 3) in the IRU package.
The transform gains corresponding to the relevant three-gyro outputs of
those three four-gyro packages can easily be identified in Table 1. As
may be seen, the only difference between the three four-gyro packages is
that each package has a different preference axis where no error ampli-
fication occurs in all three-gyro combinations. It is interesting to note
that the theoretically optimum four-gyro emplacement (Reference 1)
yields a relative variance of 1.5 for all three reference axes in all three-
gyro combinations, while, in the octahedron six-array-based four-gyro
emplacement, the three-gyro combinations yield no error amplification
on two reference axes and an error amplification factor of 3 on the third
axis. This factor shifts its location between two axes for the dif-
ferent three-gyro combinations. A compact packaging arrangement for
the octahedron six-array-based four-gyro emplacement is shown in
Figure 4.
Reliability Merits
In the octahedron six-array configuration, the useful "three-out-of-six"
gyro combinations for full attitude reference are reduced to 16 from 20,
the maximum value achievable by a six-gyro skew configuration. It is felt,
however, that the small reduction of the redundancy capability in the
six-array configuration is compensated by the great simplicity in measure-
ment processing. It is also noted that the redundancy capability of the
octahedron six-array configuration in combinatorial terms is still twice as
high as the redundancy capability of six gyros in an orthogonal em-
placement.
The four coplanar three-gyro combinations of the octahedron six-array
configuration have a smaU impact on the functional reliability of the
octahedron six-array IRU, as may be seen in Figure 5, which displays
the reUability functions of six different gyro configurations. Figure 5 was
computed assuming perfect failure monitoring accomplished by external
means (e.g., voltage sensing) and continuous operation of all gyros, with
only failed gyros turned off. These assumptions have no significant effect
on the relative reliabihty merits of different gyro configurations, pro-
vided: (1) failure monitoring has considerably higher reliability than
that for the individual gyros, and (2) the shelf-life degradation of gyros
is considerably smaller than the gyros' active wear-out rate. Additional
reliability functions for different gyro configurations and operation
modes and for different failure monitoring techniques can be found in
Reference 6.
It is noted that the octahedron six-array-based four-gyro configurations
possess the full redundancy capability that is available with a linearly
independent four-gyro skew emplacement.
116
1.0
\~^
0.8
0.6
\ \
\\^
\X
\
\
\V\
^
^
\^
\
0.4
\^ \,
\b\
\ \
\
\^
^vD^\
0.2
^\
\-, ^^^
~~^
X. = FAILURE RATE
OF ONE GYRO
t = OPERATING TIME
^^-^.,^
^"~"^
^^^^
n
1
0.4 0.6
TIME CONSTANT Xgt
0.8
A OPTIMUM (SKEW) CONFIGURATION OF SIX GYROS
B OCTAHEDRON (SKEW) CONFIGURATION OF SIX GYROS
C SKEW CONFIGURATION OF FIVE GYROS
D ORTHOGONAL EMPLACEMENT OF TWO GYROS ON EACH AXIS
E SKEW CONFIGURATION OF FOUR GYROS
F NON-REDUNDANT IRU
Figure 5. Reliability functions of six gyro configurations
Concluding Remarks
Non-orthogonal redundant gyro configurations offer several useful
operation options: (1) Operating four gyros at a given time, instant full
attitude reference is available if any one of the four gyros has failed; (2)
operating five gyros at a given time, one failed gyro can be identified by
a data processing technique; and (3) even one skewed gyro is useful for
in-line estimation of full attitude reference.
References
1. Barnhill, D. H., and Susens, D. C, "Digital Attitude Reference, Re-
dundancy and Temperature Control Considerations," paper presented
at the AIAA/JACC Guidance and Control Conference, Aug. 15-17,
1966.
2. Weiss, R., and Nathan, I., "An Ultra-Reliable Attitude Reference
System for a Manned Orbiting Laboratory with Limited Sparing
Capability," paper presented at the AIAA Guidance and Conti-ol Con-
ference, Seattle, Wash., 1966.
117
References (contd)
3. Gilmore, J. P., A Non-Orthogonal Gyro Configuration, M.S. thesis.
Massachusetts Institute of Technology, Cambridge, Jan. 1967.
4. Gilmore, J. P., and McKern, R. A., "A Redundant Strapdown Inertial
System Mechanization— SIRU, paper presented at the AIAA Guidance
and Control Conference, Santa Barbara, Calif., Aug. 17-19, 1970.
5. Pejsa, A. J., "Optimum Orientation and Accuracy of Redundant Sensor
Arrays," paper presented at the AIAA 9th Aerospace Sciences Meet-
ing, New York, N.Y., Jan. 25-27, 1971.
6. Bejczy, A. K., Reliability Merits of Different Redundant Orthogonal
and Non-Orthogonal Single-Axis Gyro Configurations, JPL Internal
Document EM 344-301-AKB. Jet Propulsion Laboratory, Pasadena,
Calif., Jan. 21, 1971.
118
JPL Quarterly Technical Review Volume 1, Number 2 July 1971
Analytically Determined Response of a 300-|Xm
Silicon Detector to a Poiyenergetic
Beam of Neutrons'
M. Taherzadeh
Guidance and Control Division
Nuclear radiation from a radioisotope thermoelectric generator used as the
prime energy source for electrical power in a space mission could severely
affect scientific instruments or detectors on the spacecraft. Therefore, a thor-
ough analysis and evaluation of the types of radiation and their effects on tlie
detectors were necessary.
In this article, the response of a 300-/u.m silicon detector to an incident
poiyenergetic neutron beam emitted from a plutonium dioxide fuel power
source is determined. The results indicate that the response of the detector
is basically due to elastic scattering reactions, and the contribution from
other reactions is very small. For neutron energies greater than 4.5 MeV, the
{n,p) and (n,a) reactions contribute less than 2% to the total response. The
maximum response for this detector is less than 4 X 10-''' cojnts/neutron
within the range of bias energies of 25 to 250 keV. Moreover, this maximum
value will decrease if consideration is given to the pulse height defect
phenomenon.
Introduction
Nuclear radiation (mainly, neutrons and gamma rays) is emitted when
a radioisotope thermoelectric generator is used as the prime energy
source for electrical power on a spacecraft. The neutrons and photons
are emitted from the plutonium fuel power source with a flux level that
depends upon the impurities and the age of the fuel itself. The neutrons
interact directly with the spacecraft's scientific instruments or detectors;
also, when detectors are shielded against primary photons, additional
radiation is generated by inelastic scattering and the radiative capture
of the source neutrons within the shield. Since this radiation could
severely affect the detectors, it is essential that the types of radiation
and their effects on the detectors be thoroughly analyzed and evaluated.
^Based on Reference 1.
119
Response of a Bare Detector
The response of a bare 300-/j,m silicon detector to neutrons can be
studied by an analytical scheme using the probability laws of interac-
tions and energy and angular distributions. In the case of a bare, very
tliin detector such as discussed here and low-energy neutrons, the pulse
Iieiglit can be estimated easily using kinematical equations. This, of
course, does not mean that the exact response can be calculated by
such a simplified scheme. Nevertheless, if the response of a silicon de-
tector is estimated for a worst case and shown to be much below the
response to the primary gamma rays from the source, the importance
of neutrons as far as additional shielding is concerned would be reduced.
Since the main emphasis of this analysis is the response to neutrons
emanated from a plutonium dioxide fuel power source, the neutron
source spectrum is examined first.
The neutron flux and the flux spectrum of a typical plutonium dioxide
fuel power source are presented in Figure 1. The fuel is a multihundred-
watt (2-kW) power source that emits a total of 4.59 X 10* neutrons/g-s.
At 50 cm from the center of the source and at zero angle with respect
to the major axis of the fuel, the total flux is 5.43 X 10^ neutrons/cm--s.
From this flux distribution, it is concluded that the average neuti-on
energy is about 2 MeV, and the maximum neutron energy can be as
high as 10 MeV or more, but with a very small neutron abundance.
In order to limit the analysis to the number of nuclear reactions
involved, a maximum can arbitrarily be set for the neutron energy so
that the percent of neutrons to be ignored contributes an insignificant
amount to the overall response of the detector. One such arbitrarily
selected maximum energy is 6 MeV; the neutrons with energies above
this value contribute less than 0.5%.
With a range of energies for the released neutrons having been
selected, the response of a silicon detector to a beam of neutrons
emitted from a plutonium dioxide fuel power source can now be cal-
culated. The total and the partial neutron cross sections as functions of
neutron energies up to 6 MeV (Reference 2) are presented in Figure 2.
Elastic scattering {n,n) and inelastic scattering {n,n'y) reactions and
(«,«), {n,p), and radiative capture (n,y) reactions (the neutron disappear-
ing reactions) are considered here. The significant features of these cross
sections are:
(1) The {n,p) and (n,a) reactions become important beyond a neutron
energy of about 4.5 MeV; however, at these high neutron energies,
the neutron abundance diminishes very rapidly. For this reason,
reactions that are kinematically possible but have high threshold
energies, such as (n,2n) reactions, are not included in this analysis,
120
4 6 8
NEUTRON ENERGY, MeV
Figure 1. Neutron f!ux spectrum as a function of neutron energy
and the contributions from such reactions should be considered
extremely small.
(2) At low neutron energies (i.e., below 1.5 MeV), only (n,n) and (n,y)
reactions are possible.
(3) In the medium range of neutron energies (i.e., 1.5 to 5 MeV), the
difference between the total cross section and the elastic scattering
cross section increases with energy, but the di£terence still re-
mains small. This means that, in this neutron energy range, the
{n,n) reaction is the most important.
Thus, the (n,p) and (n,a) reactions can be considered, as a source of
background, but the {n,n) reaction is by far the largest contributor. The
(n,y) and {n,n'y) reactions have much smaller cross sections, and the
121
4 6
NEUTRON ENERGY, MeV
Figure 2. Neutron cross section as a function of neutron energy
emitted photons escape the detector's sensitive area before depositing
any energy. In Table 1, the neutron-silicon reactions are listed with
their corresponding emitted secondary particles and various character-
istics of the reactions. The (n,2n) reaction is included as an example of
the reactions that will not be considered due to their high threshold
energies and low neutron flux levels.
The response function of a detector medium at a given neutron energy
£„, and when angular distribution in the center-of-mass (CM) system is
assumed isotropic is given by
/•(Bs,)„.,^£ r/ <a£>\ya2v + 1
£si J^ 2
X av (E.n)Pv ( 1 ^ ) + e„,p(E„) 8„,;,
\ yfl-C-n /J
(1)
where Ej, is the bias energy; e terms are efBciency functions; (£si)max is
the maximum silicon recoil energy; yo is a constant that, for the silicon
recoil, is 0.1332; and < a£ >/Esi is the fraction of non-ionizing energy
dissipated in the medium and, thus, not contributing to the charge col-
lection process of the detector. The Pv term represents the Legendre poly-
nomials of degree v, with av as their coefiicients; these energy-dependent
122
Table 1. Characteristics of neutron-silicon reactions^
Type of
reaction
Specific
reaction
Quantity of
heat Q,
MeV
Threshold
neutron
energy (E„)th,
MeV
Neutron
abundance
at (£„)„„
%
Neutron
disappearing
Si28(n,a)Mg2=
-2.7
2.66
13
Neutron
disappearing
Si2s(n,p)Al28
-3.9
3.66
8.3
Elastic scattering
Si28(n,n)Si28
—
Inelastic scattering
Si28(n,?i'7)Si28
—
Radiative capture
Si28(n,7)Si2»
8.47
—
Other particle
producing
Si2''(»,2n)Si2s
-8.47
8.81
0.14
Other particle
producing
Si2s(n,«'p)Al"
-11.6
12.06
—
Maximum
energy of
charged
particles,
MeV
Range of
charged
particles.
^m
Reaction
cross
section,''
cm2 X 10-2*
( = barns)
1.81
0.798
9
44
0.045
2.915
0.00364
0.0111
"Maximum neutron energy (£„.),„ax ~ ^ MeV.
i>44- 1 K \Hc^\r
coefficients are obtained from Reference 3, where up to a ninth-order
polynomial was used to reproduce the angular distribution of the neu-
trons. All nine coefficients at any neutron energy are used in this calcu-
lation. The Sa,-, term represents the fact that {n,a) and {n,p) reactions can
contribute to the total response if Ea,p — < AjE > a,p > Eb-
The detector's efficiency function for normal incidence, £d{E„
erally given by
IS gen-
€j3{E„
exp
"<«■
{En)t]
(2)
vv-here /x(E„) is the attenuation coefiicient of the detector and t is the
sensitive thickness. The curves for the efficiency functions for {n,n), {n,p),
and {n,a) reactions and the curve for the total value for a 300-^m silicon
detector are presented in Figure 3. The shape of the curve for the total
10
-w
1
1
TOTAL
-
-
(n,n)
^^
-
-
/(n-p) /
-
-
/
An, a)
-
-
1 1
/
1
-
4 6
NEUTRON ENERGY, MeV
Figure 3. Efficiency function e^ (E„) as a function
of neutron energy
124
value follows that for the total cross section because the effective thick-
ness of the detector is small and
eoiEn) ='tN(T{En)
(3)
where Na is the neutron cross section. Since the energy transferred to the
silicon by neutrons is 0.133E„ sin- (6Icm/2), where ^cm is the angle in the
CM system, (£si)max is obtained when v = 0, ^cm = 180 deg, and the
energy distribution function for the silicon nuclei after collision is
l/(£si)max. The probability function is given by 1 — [EB/(Esi)max], and
the response function is
R{En,EB) = €u{En,t) il~ 133^^. ) ■■
(4)
In Figure 4, the response function is plotted for various values of £„
and Eb- The contribution from protons generated in {n,p) reactions and
the contribution from alpha particles generated in (n,a) reactions are
indeed small. At low E„, these charged particles do not exist; at high E„,
the contribution from protons is more than one order of magnitude lower
and the contribution from alpha particles is about five orders of magni-
tude lower than the pulse height generated by elastic scattering of neu-
trons. Therefore, at E„ up to 5 MeV, the major portion (~99%) of
Figure 4. Silicon response function R (E^,, E^) as a
function of bias energy
125
counts comes from the silicon nuclei after being struck by neutrons, and,
at 6 MeV, nearly 90% of the response is due to this reaction. The protons
and alpha particles generated within the detector are completely ab-
sorbed since the edge effects are small. For this reason, they must be
included in the pulse height calculation since the time interval for the
ionization process is much smaller than the charge collection time inter-
val, and the deposited energy is equal to the maximum energy if it is
above Eb-
The neutron flux </> from the fuel capsule can also be included in the
response function; thus, in the [0,(E„)„iax] energy interval, the response
of the silicon detector at £.» is
where A is the detector's cross-sectional area and dC{En /cZE„ is given in
counts/(neutron/cm^)-MeV. The total silicon counting rate for a poly-
energetic neutron beam with energies up to (E„)n,ax is
C{E„)= f^''"'""^<j.(E„)ARiE^,Es)dEn (6)
where (£„)min is the minimum neutron energy allowed for a given Eb
(i.e., 7.55Eb).
Equation 6 is plotted in Figure 5 for the same En values used in
Figure 4; C(£'„) is given in counts/s for energies from (£„)min up to
(finjmax- Tlic total couutiug rate at a given £„ depends upon Eb- At
Eb = 100 keV and £„ = 5 MeV, the counting rate is about 20 counts/s
when angular distribution is assumed isotropic; no pulse height defects
are taken into account, and the total neutron flux for this case is only
151 neutrons/cm--s.
Response of a Detector Subject to Pulse Height Defects
The response function calculated in the previous section is yet subject
to another restriction, namely, the pulse height defect. This effect is
more pronounced in the case of silicon detectors because the pulse height
is mainly due to the elastic scattering of neutrons.
Neutrons transfer their energies to the silicon-sensitive medium by
atomic scattering and nuclear reactions, rather than through an electronic
ionization process. The secondary charged particles produced by the
neutron interaction, such as protons, alpha particles, and silicon nuclei.
126
<
o
10
10 ■
1 1
1 1 1
NEUTRON ENERGY E =
-
^\.5.90 MeV
\ 1 .32 MeV
-
0.27 MeV
1^
\ E^ = 5 .90 MeV — Tj
(n,a) X 100
frj'P)
! 1
1 1 1
100 150 200
BIAS ENERGY, keV
250 300
Figure 5. Total counting rate C (E„) as a function
of bias energy
in turn transfer their energies to the medium by ionization and nuclear
charge scattering. The photons generated in the (n,y) and {n,n'y) reac-
tions escape the medium in most cases and thus will not deposit energy.
The non-ionizing processes contribute to the pulse height defect. The
ionization causes the displacement of electrons, while nuclear charge
scattering (Rutherford scattering) causes the displacement of atoms from
their equilibrium position and leaves vacancies in the lattice.
The maximum energies and ranges of the protons, alpha particles, and
silicon nuclei were presented in Table 1. Since 300 ^am was selected as
the depletion depth of the detector, nearly all of these charged particles
remain inside. The energy transferred to the silicon is (E|;)n,ax sin- ((9cm/2),
where (E^Jmax is the maximum transmitted energy. If fj is the ratio of
127
the mass of the silicon atom to the mass of the ith charged particle
(namely, proton, alpha particle, or silicon nucleus), then
EL = 4r;Ei (1 + r,y-
Since r^ = 28, Va = 7, and rgj = 1,
(-E|i)n,ax=0.1332(£,)„,,,
(EI.U. = 0.438(E„)„,,,
\ Si /"l^^ (^Si/max
If the maximum energies of the charged particles for a 6-MeV neuti'on
beam from Table 1 are used, then
(E|i)n
(ElX
(EU)rr
240 keV
1170 keV
798 keV
However, in tire real case, only fractions of these energies are transmitted
to the medium by ionizing processes, and the remainder contribute to
the pulse height defect.
Figure 6 presents the fraction of the pulse height defect as a fimction
of the charged particle energy and considers up to two neutron scatters.
It may be seen that the pulse height defect is important only at low
z O.f
o
0.6 -
0.4
0.2 -
-
1 1
-
-
PROTONsX
\ ALPHA ^
\ PARTICLES
\ SILICON
\ NUCLEI
-
1 1
"^
^X.
IQ-' 10" 10' 10^ lO'^ 10^
CHARGED PARTICLE ENERGY, keV
Figure 6. Pulse height defect fraction as a function
of charged particle energy
128
energies, and, within this range, the pulse height defect due to the silicon
nuclei is much greater than that due to protons or alpha particles. For
example, for a 100-keV charged particle energy (E„ = 4.5 MeV for pro-
tons, 4.0 MeV for alpha particles, and 0.75 MeV for silicon nuclei), the
pulse height defect due to protons is about 6 keV, that due to alpha
particles is about 12 keV, and that due to silicon is about 60 keV.
The pulse height defects can now be included in the silicon responses
presented in Figure 4. For E„ = 1.32 MeV, only silicon nuclei with a
maximum energy of 175 keV need to be considered; if Eb is set at
higher values, there would be no response. The pulse height defect at
this energy (Figure 6) indicates that 58% of the energy is transmitted
to the medium by the non-ionizing processes; thus, Eb needs to be set
even lower (74 keV) if any response is desired. At high E„, (i.e., 6 MeV),
the maximum energies of the charged particles are those given in
Table 1, and the pulse height defects are 48 keV for protons, 159 keV
for alpha particles, and 528 keV for silicon nuclei. This means that pro-
tons and alpha particles will contribute to the total response, but there
will be no pulse height due to the (n,n) reaction if Eb > 270 keV.
Concluding Remarks
The following remarks summarize the results of this analysis:
(1) For the £„ range of 0.27 to 6 MeV and Eb range of 25 to 250 keV,
the maximum response of a 300-/j;m silicon detector is about
4 X 10"^ counts/neutron.
(2) For an E„ or Ey of 3 MeV and an Eb of 50 keV, the response of
the silicon detector to neutrons is about 11% of the response to
the source gamma rays (i.e., R„ = 0.0029 and Ry = 0.025; Ref-
erence 4).
(3) For an Eb range of 50 to 250 keV and for a neutron flux emitted
from a multihundred-watt (2-kW) plutonium dioxide fuel power
source, the counting rate is estimated to be about 31 to 5 counts/s.
Acknowledgment
The author wishes to express his appreciation to Dr. M. Reier of the
JPL Guidance and Control Division for his valuable remarks during this
investigation.
References
1. Taherzadeh, M., and Anno, G., "The Response of a 300|a Silicon De-
tector to Monoenergetic Neutrons Determined by the Use of the
129
References (contd)
Monte Carlo Technique," paper presented at the National Symposium
on Natural and Man-Made Radiation in Space, Las Vegas, Nevada,
March 1-5, 1971, sponsored by AEC/NASA (proceedings to be pub-
lished).
2. Ray, J. W., et al, Neutron Cross Sections of Nitrogen, Oxygen, Alumi-
num, Silicon, Iron, Deuterium, and Beryllium, UNC-5139. United
Nuclear Corporation, Elmsford, N.Y., Nov. 1965.
3. Campbell, R. W., et al.. Compilation, Evaluation and Deduction of
Neutron Diferential Scattering Data, Vol. IV, NAA-SR-11980. Atomic
International, 1967.
4. Reier, M., The Response of a Shielded 300fx Silicon Detector to Mono-
energetic Gamma Rays From 0.279 to 2.75 MeV, JPL Internal Docu-
ment EM 342-118. Jet Propulsion Laboratory, Pasadena, Calif., Sept. 14,
1970.
130
JPL Quarterly Technical Review Volume 1, Number 2 July 1971
Remote Examination of Rock Specimens
J. D. Burke
Advanced Technical Studies Office
R. Choate
Space Sciences Division
R. B. Coryell
Project Engineering Division
In JPL studies of prospects for post-ApoZto lunar exploration, methods are
being considered for extending the Apollo observations into a more complete
understanding of the moon's bulk composition, mode of accretion, and ther-
mal history. Based on Apollo samples to date, it appears that relatively
simple remotely controlled methods may be adequate for characterizing lunar
materials found along extended surface traverses. To investigate this possi-
bility, studies and experiments have been made to determine ( 1 ) what per-
formance can be expected from a minimvmi rover-borne system with imaging
and sample manipulation, and (2) the advantages conferred by desirable
additions, such as close-up color imaging, various types of microscopy, and
chemical or mineral analysis using X-rays. Laboratory and field experiments
reported in this article support the feasibility of this prospect and identify
some characteristics of an automated system required to realize this technique.
Introduction
In JPL studies of prospects for post-ApoHo lunar exploration, one
objective has been to find methods for extending the Apollo observations
into a more complete understanding of the moon's bulk composition,
mode of accretion, and thermal history. With the suite of Apollo samples
as a starting point, it appears that relatively simple remotely conti-oUed
methods may be adequate for characterizing lunar materials found along
extended surface traverses. To investigate this possibility, studies and
experiments have been made to determine (1) what performance can be
expected from a minimum rover-borne system with imaging and sample
131
manipulatioa, and (2) the advantages conferred by desirable additions
such as close-up color imaging, various types of microscopy, and chem-
ical or mineral analysis using X-rays.
These remote techniques cannot, of course, equal the quality and
variety of the analytical methods available on earth. However, because
of the great amount of information provided by Apollo at isolated surface
sites, extension to other regions may be feasible with more limited
methods. The object of the tests reported here was to verify this prospect.
Laboratory Imaging Experiments
The first task was to determine the general performance limits of imag-
ing systems required for the later work. By means of simple experiments
in the Image Processing Laboratory, it was found that standard closed-
circuit television systems available on loan from other JPL programs
could be used with minor modifications to simulate the ranges of reso-
lution and other picture parameters considered practical for transmission
from lunar rovers (Reference 1). Samples of sand (Figure 1) with various
particle sizes and shapes were used to define the limits of acceptable
illumination, magnification, contrast, and so forth for identification of
the material being viewed. Next, rock samples were examined and it
Figure 1. TV image of two sand samples; particle
size 100-500 ^m
132
was immediately evident that identification would require three more
features :
(1) An ability to rotate the sample, the camera, and the direction of
illumination relative to each other.
(2) A size calibration such as a scale in the field of view (or, if an in-
ternal reticle is used, a measurement of distance to the sample).
(3) A gray scale in the field of view.
These provisions were easily added in the Science Experiment Test
Laboratory (SETL), and a series of identification tests were run using
the setup shown in Figures 2 and 3. The samples, mounted on a pan-
and-tilt stand and illuminated by the movable coUimated light source
built for Surveyor shadow simulations, were viewed via black-and-wliite
television cameras (with various lenses) by several experienced geologists,
petrologists, and mineralogists who recorded their observations, com-
mented on the adequacy of picture parameters such as magnification and
depth of field, and attempted to identify the rocks. Then, following the
TV session, each observer viewed the samples directly and, if desired,
with a hand lens to verify or correct his previous identifications. In this
way the limits of required system performance were outlined for various
Figure 2. TV cameras with zoom and stereo attachments viewing sample illumi-
nated by movable collimated light source. Pan-and-tilt stands and camera lenses
are remotely controlled
133
J
,; ■■■ 1 i
, --.,|- -.1
Figure 3. Control console for remote manipulators and cameras. Window
is curtained to prevent direct viewing during tests
classes of samples. As expected, freshly broken rock surfaces were pre-
ferred by all observers; an ability to break open the lunar samples is
obviously desirable, particularly when the ubiquitous lunar dust is con-
sidered, and is feasible as shown by Surveyor experience (Reference 2).
The results of this first test series are summarized in Table 1.
The observers were asked to evaluate their own ability at describing
rock textures by use of the remote TV system in comparison to their
ability with a hand-held specimen. Evaluations were mostly restricted to
about five di£terent rock specimens, ranging in type mainly from fine-
grained basalt to medium-grained diorite. The specific textural features
evaluated included the four principal ones listed by Tyrrell in Principles
of Petrology (Reference 3). The ratings for the individual petrographers
mostly ranged between 75 and 100% ; the extreme values, based on indi-
vidual specimens, ranged from 40 to 100%. The mean values for
the principal textures (as averaged for the observers) are: degree of
crystallinity, 83%; grain size, 95%; grain shape and crystal-face develop-
ment, 85%; and intergrain relationships, 80% (Table 1). The average
for all petrographers for these four principal textural features was 85%.
The observers' evaluation of their capability at mineral identification
via remote T\' ranged from 50 to 75% of their ability with a hand-held
134
Table 1. Quantitative evaluation of the petrographic data obtained by 300-line
resolution TV in comparison to a hand-held specimen=>
U)
Petrographer
Textural features
Mineral identification features
Degree of
crystallinity
Grain
Average for major
textural features
Grain shape
and
Intergrain
Volcanic
Number of
Mineral
crystal face
relationship
textures
minerals present
identification
development
Number 1
100
100
75
75
75
50
75
Number 2
40
100
95
100
90
100
75
100
70
90
60
50
Number 3
75
100
75
50
—
—
50
Number 4
100
75
75
75
—
—
—
Number 5
90
100
100
100
80
90
80
—
50
—
Average for individual
features
85
95
85
80
75
65
60
85
Overall average
'*A11 values to nearest 5%.
80
specimen using a lOX hand lens. The average value for all petrographers
was between 60 and 65% . The average for all seven textural and mineral
identification features that were individually rated was 80% (Table 1).
The major diificulty in the evaluation program was inadequate reso-
lution of the first TV system used, so that certain critical mineral phe-
nomena, such as twinning, cleavage, and color differences, were either
not visible or were not identifiable. Object resolution based on tests with
high-contrast sand grains was approximately 50 ixin. Center vertical and
horizontal resolution of the TV pictures averaged approximately 300
lines. Substantially better resolution and much higher magnifications were
available in the TV systems used in later tests; the data reported here
are for the early system, representing about the minimimi acceptable
from a lunar rover.
Several observers emphatically stated that detailed visual examination
should be not only the first but also the primary technique used in
analysis of rock specimens on any automated long traverse. It was empha-
sized that it should be possible to determine 80 to 90% of the petrographic
information in most rock specimens — pertaining to textures and to identi-
fication of the essential and main accessory minerals — ^from any technique
equal to that of hand-specimen field examination with a 10-power hand
lens. A major advantage of visual examination is that many specimens
can be examined rapidly; dming a lunar or planetary mission, the visual
images and other data concerning these rock specimens would be re-
corded on magnetic tape for later detailed evaluation.
It is readily acknowledged that the study of textures, including all
those discussed above, is best done in thin section under a petrographic
polarizing microscope. However, the problems involved in the complex
preparation of thin sections remotely on the moon, the cost in payload
weight, and the probable consumption of substantial mission operations
time all weigh against this procedure in the near future. A useful substi-
tute for thin-section examination is the observation of freshly broken rock
specimens in reflected light under high magnifications of 40 to 50 power.
If the capability of examining mineral fragments under transmitted
polarized light is also added, then powerful scientific tools indeed are
available for use by the lunar or planetary geologist — tools both for rapid
mineral identification and for textural description of the rocks encountered
on a traverse.
Field Experiments
Following the tests with isolated specimens, the next logical step was
to add the information that is available to an accomplished geologist
when he views the surroundings in which the sample is found. On two
occasions JPL has experimented with remotely controlled instruments in
136
the Southern California desert. The purpose of these experiments has
been to identify functional and operational requirements for a remotely
controlled mobile payload.
The first experiment, reported in References 4 and 5, used a battery of
four TV cameras mounted on top of an electronics van (Figure 4). A
geologist inside the van was provided an 80-deg field of view on foui-
monitors (Figure 5). A fifth monitor allowed the geologist to direct the
operation of the sampling TV camera and various sampling instruments
outside the van (Figure 6).
[::.;v
':S3rT
% <d' %
Figure 4. Truck used for field tests, stiowing controllable array of TV cameras
137
Figure 5. TV monitors inside truck for first test
S^'"'
;X
'
f.-. M »
■■
/
"'^•"S-^A
/.
/.
'§■'■■■
■■" /-'
'■■■■, /' "
M'^J o--*
;',
•''Mj '. '
■ '.
mi ' '^
't*
f/--'^41
Figure 6. Surveyor sampler and sampling camera
138
Exercises in geological reconnaissance with TV imagery were con-
ducted at 13 stations and sampling exercises at 9. Sample analysis was
limited to imagery obtained by the sampling camera (zoom lens in-
cluded). Conclusions made or confirmed by these exercises are listed in
Table 2.
The second experiment, conducted in December 1970, used the same
van. In place of TV cameras with overlapping field of view, film pan-
oramas, simulating the images that would be obtained by a photof acsimile
scanner on a lunar rover, were used. They were displayed by mounting
an illuminated positive transparency above the TV monitors (Figure 7).
1 I
J\
Figure 7. Dispiays used in second test: (top) panorama, (center)
dose-up of sample, (bottom) two views of near field
A surveillance TV camera (Figure 8) was mounted at the site from
which the film panorama was made. A sample analysis TV camera was
installed closer but exterior to the van, both cameras with zoom lenses
and controlled remotely from inside the van. Rock specimens were
mounted on a pan-and-tilt machine adjacent to the sample analysis
camera (Figure 9).
139
Table 2. Resume of geological conclusions from field data
Operational procedure
Uamera parameters
(^rouna system constraints
o
1. Direct sampling of surface material is re-
quired to supplement the TV data.
2. Reconnaissance geology requires data on
the texture of surface material and either
mineral phase data or elemental compo-
sition data or both.
3. Surveyor surface sampler is preferred over
drill or auger.
4. Properly instrumented rover can per-
form geological reconnaissance, but not
detailed geological mapping.
5. In addition to data taken at stations, the
geologist would like data taken en route
between stations.
6. Geological observations will modify the
traverse route and selection of stations.
1. Some technique of ranging to observed
features is required.
2. Some technique of sizing observed fea-
tures required.
3. Color vision is not particularly important
for reconnaissance observations; how-
ever, color vision is important in rock
and mineral identification.
4. Stereo vision is not required but may be
useful in showing relative range of fea-
tures.
5. Resolution for observing panoramic dis-
play is not particularly critical; however,
resolution for examining textures should
be able to resolve grains as small as
0.05 mm in diameter.
1. 360-deg panoramic display of botli hori-
zon and near-field should be displayed.
2. High-resolution view of selected areas
contained in panoramic view is required.
3. Panoramic view must first be displayed
for observations of immediate interest
and mapping. A permanent copy of im-
agery should be made for subsequent
study.
4. The reconnaissance map, with observed
geology, will have to be kept up to date
with vehicle progress.
VS-'l
^ 3\«-8JlV.-
Sfc.-^-;..
tU''
■I 'J -''r-^'
■'^
Figure 8. Surveillance TV camera and field test vehicles
To simulate a remote compositional analysis, some samples were
analyzed following the field experiment by Mr. Sean Gary at Los Angeles
City College using the X-ray diffraction technique. Correlation of petro-
graphic data from the sample analysis camera and the X-ray diffracto-
grams is currently in progress.
A team of three or four geologists in the van (Figure 8) performed
geomorphologic analysis on the film panorama, examined distant features
via the surveillance camera, selected rock specimens and fines with that
camera, and made petrographic analyses of samples. Conclusions on
geomorphology, rock units, and structure were then plotted on an aerial
photograph of the area. The geologists were not permitted to view the
test areas directly, either from the ground or from the air.
At seven stations, covering volcanic terrain, igneous intrusives, and
sedimentary sequences, field exercises tended to confirm the earlier con-
clusions. Final conclusions await completion in the laboratoiy of the
sample analysis. However, certain observations are very clear: Imagery
made available to the geologists allowed them to select samples
representative of the area. The gross geologic character of most areas
141
v ' -■
Figure 9. Close-up camera and sampie during second field test series
was quite evident from the overhead photography and panoramas. Pan-
oramic imagery was found to be very effective in locating sampMng sites
and providing an integrated view of geological features.
References
1. McCormick, C. W., and Bailey, G., Remote Visual Examination of
Rock Specimens, JPL Internal Document 760-47. Jet Propulsion
Laboratory, Pasadena, Calif., May 1970.
2. Surveijor Project Final Report: Part I. Project Description and Per-
formance, Vols. I and 11, July 1, 1969, and Part II. Science Results,
June 15, 1968, Technical Report 32-1265. Jet Propulsion Laboratory,
Pasadena, Calif.
3. Tyrrell, G. W., The Principles of Petrology, p. 394. Methuen & Co.,
Ltd., London, 1926.
142
References (contd)
4. Brereton, R. G., Coryell, R. B., Howard, E. A., and Eubin, D. K.,
Experiments in Remote Geological Reconnaissance and Landmark
Navigation, JPL Internal Document 760-41. Jet Propulsion Laboratory,
Pasadena, Calif., Oct. 15, 1969.
5. Brereton, R. G., and Howard, E. A., "Comments on Geological Obser-
vations From an Automated Vehicle (Field Test)," in Supporting Re-
search and Advanced Development, Space Programs Summary 37-55,
Vol. Ill, pp. 258-263. Jet Propulsion Laboratory, Pasadena, Calif.,
Feb. 28, 1969.
143
Bibliography
of Current Reporting
Author Index With Abstracts
ABHYANKAR, K. D.
AOl Effect of Absorption on Scattering by Planetary Atmospheres
A. L. Fymat and K. D. Abhyankar
J. Geophys. Res., Vol. 76, No. 3, pp. 732-735, January 20, 1971
For abstract, see Fymat, A. L.
ALLEN, J. E.
A02 DSN Progress Report for March-April 1971:
DSN P/lonitor Analysis System
J. E. Allen
Technical Report 32-1526, Vol. Ill, pp. 224-227, June 15, 1971
Some major changes within the Monitor System in both the
facilities and the operation group have necessitated personnel
and procedure changes within the Deep Space Network (DSN)
Monitor Group at the Space Flight Operations Facility (SFOF).
The ^/[onitor Group has taken a positive role in the development
of the DSN monitor at the SFOF, has become more aware of the
monitor system hardware, software, and conceptual design, and
the system is developing into a more meaningful and useful activ-
ity. This article describes the status of the DSN Monitor Analysis
Group and the progress of the monitor system as it relates to its
ability to support flight projects utilizing the Mark III software
packages and the IBM 360/75 computer.
BACK,, L. H.
BOl Static Pressure Measurements Near an Oblique Shock Wave
L, H. E3ack and R. F. Cuffel
AIAAJ., Vol. 9, No. 2, pp. 345-347, February 1971
146
The appraisal of readings of relatively short static pressure probes
in the vicinity of an oblique shock wave is discussed in this
article. Such probes are used along with pitot tubes to determine
the Mach number distribution in supersonic flow fields. In the
absence of shock waves in the flow, an upstream length of 15-
probe diameters from the hole to the tip has been found to be
sufficient to allow the local static pressure upstream of the probe
bow shock wave to recover within about 1%. E[owever, when
traversing the probe across an oblique shock wave, the interaction
between the probe bow shock wave and the oblique shock wave
can influence the flow field along the probe, particularly where
the pressure is measured.
The purpose of the investigation reported here was to learn about
the lateral extent of the interaction region so that measurements
can be properly interpreted. There is usually no problem with
obtaining accurate pitot tube measurements, because the pitot
pressure is influenced by the bow shock-oblique shock wave inter-
action at distances less than one tip height; therefore, the region
of influence can be reduced by using a probe with a small tip.
However, the size of the static pressure probe is limited by
strength considerations; in addition, the measured pressure is
expected to be influenced at distances greater than a probe diam-
eter because of the configuration of the probe and the oblique
shock wave.
B02 Flow Coefficients for Supersonic Nozzles With Comparatively
Small Radius of Curvature Throats
L. H. Back and R. F. Cuffel
J. Spacecraft Rockets, Vol. 8, No. 2, pp. 196-198,
February 1971
This article discusses the determination of the mass flow rate
through choked nozzles, with emphasis on comparatively small
radius-of-curvature throats. In the flow regime investigated (throat
Reynolds numbers larger than 10*'), viscous (boundary-layer) ef-
fects are not believed to be significant, so the flov/ field can be
regarded as essentially isentropic. Mass flux nonuniformities for
the air flows studies are then primarily caused by the throat con-
figuration and result in reduced mass flow rates below the ideal
one-dimensional flow value, since, in either the subsonic flow
region near the centerline or the supersonic region near the wall,
the mass flux is less than that at the sonic condition. The nozzles
considered have circular-arc throats with values of fc/fn, the
147
ratio oiF throat radius of curvature to throat radius, extending from
2 dovi'n to nearly 0, corresponding to a sharp-edged throat.
Measured values of the mass flow coelBcient are presented for
nozzles recently tested at JPL and for nozzles previously tested
in other investigations. Of interest is the relative correspondence
of the earlier measurements by Durham that span a large range of
rc/rti, to the recent data, since there is some question about their
absolute magnitude due to the accuracy of the measurements
made in a blow-down facility. These measurements, taken collec-
tively, provide a basis on which to evaluate the effect of rjrtn on
the flow coefficient and to appraise existing and recently devel-
oped prediction methods for isentropic flow by other investigators.
603 A Magnetic Tape Recorder for Long Operating Life in Space
E. Bahm
JPL Quarterly Technical Review, Vol. 1, No. 1,
pp. 116-124, April 1971
In the past, magnetic tape recorders for space applications have
caused many problems. However, they are still widely used be-
cause they are the only mass memory device acceptable for space-
craft. Most of the tape recorder problems have been associated
with the mechanical tape transport, while the tape recorder elec-
tronics generally achieved a satisfactory performance record. This
article describes a tape recorder which uses a very simple mechan-
ical system to transport the tape with very few possible failure
modes. The simplicity of the tape transport has been achieved at
the expense of added complexity of the electronic system. The
resulting tape recorder is better balanced in its mechanical and
electronic reliability. The test results with a feasibility model have
been very encouraging.
BARKER, E. S„
B04 High-Dispersion Spectroscopic Observations of Venus:
¥. The Carbon Dioxide Band at 8689 A
L. D. G. Young, R. A. J. Schorn, E. S. Barker (University
of Texas), and M. MacFarlane (University of Texas)
Icarus; Int. J. Sol. Sys., Vol. 11, No. 3, pp. 390-407,
November 1969
For abstract, see Young, L. D. G.
148
805 High-Dispersion Spectroscopic Observations of Venus:
Vfl. The Carbon Dioxide Band at 10 488 A
L. D. G. Young, R. A. J. Schorn, and E. S. Barker (University
of Texas)
Icarus: Int. J. Sol. Sys., Vol. 13, No. 1, pp. 58-73, July 1970
For abstract, see Young, L. D. G.
BARTZ, D. R.
B06 Characteristics, Capabilities, and Costs of Solar Electric
Spacecraft for Planetary Missions
D. R. Bartzand J. L. Horsewood (Analytical Mechanics
Associates, Inc.)
J. Spacecraft Rockets, Vol. 7, No. 12, pp. 1379-1390,
December 1970
Since 1965, when the feasibility of using solar-photovoltaic-
powered, electrically propelled spacecraft for planetary missions
was first suggested, the propulsion system technology has been
developed to near-readiness; additionally, further studies have
been made to gain a clear perspective of the mission applicability
of solar-electric spacecraft. It was felt that a summary of the cur-
rent characteristics, capabilities, and costs of solar-electric space-
craft for planetary missions might prove useful in suggesting:
(1) those missions for which solar-electric propulsion is best
suited, and (2) the advantages that can accrue from the multi-
mission use of a given solar-electric spacecraft design. Such a
summary is presented in this article.
BATHKER, D. A.
B07 Predicted and Measured Power Density Description
of a Large Ground Microwave System
D. A. Bathker
Technical Memorandum 33-433, April 15, 1971
A comparison between predicted and measured microwave field
strengths on, near, and in the far field of a large ground antenna
system is given. The system consists of a high-power S-band trans-
mitter and a parabolic reflector. Use of the radiations patterns of
the feed system is adopted as accounting for the total power out-
put. Estimates of secondary or stray radiation are given and dis-
cussed. A first-order tubular beam concept is introduced to sim-
plify and provide a clear impression. It is concluded that certain
149
safety restrictions are necessary; a discussion of these restrictions
is included.
BEERER, J. G.
608 Mariner Mission to Venus and Mercury in 1973
R. D. Bourke and J. G. Bearer
Astronaut. Aeronaut., Vol. 8, No. 1, pp. 52-59, January 1971
For abstract, see Bourke, R. D.
BENOIT, R. E.
B09 Microbial and Ecological Investigations of Recent Cinder Cones,
Deception Island, Antarctica— A Preliminary Report
R. E. Cameron and R. E. Benoit (Virginia Polytechnic institute)
Ecology, Vol. 51, No. 5, pp. 802-809, Late Summer 1970
For abstract, see Cameron, R. E.
BENSON, G. S.
BIO Resonances in the Neptune-Pluto System
J. G. Williams and G. S. Benson (University of
California, Los Angeles)
Astron. J., Vol. 76, No. 2, pp. 167-177, March 1971
For abstract, see Williams, J. G.
;.E\8, R. A.
F 1 i A Preliminary Control Net of Mars
M. E. IDavies (Rand Corporation) and
R. A. E^erg (USAF Aeronautical Chart and Information Center)
J. Geophys. Res., Vol. 76, No. 2, pp. 373-393, January 10, 1971
For abstract, see Davies, M. E.
BIRD, E. F.
B12 DSN [Deep Space Network] Progress Report for
March-April 1971:
GCF Television Assembly Design for the Systems
Development Laboratory
E. F. Bird
150
Technical Report 32-1526, Vol. Ill, pp. 187-189,
June 15, 1971
The newly constructed Systems Development Laboratory (SDL)
at the Jet Propulsion Laboratory will serve as an extension of the
Space Flight Operations Facility (SFOF). The Pioneer Project
will utilize the SDL for conducting the operations of the Pioneer
F and G missions. The Ground Communications Facility (GCF)
provides intercommunication between the SDL and the SFOF.
One of the communication media is television. This article defines
the requirements and the resulting design of the GCF Television
Assembly in the SDL.
BOND, F. E.,JR.
B13 DSN [Deep Space Network] Progress Report for
January-February 1971:
The Teletype Discipline of Data Transfer Designed for
Support of Mariner Mars 1971 Missions
F. E. Bond, Jr.
Technical Report 32-1526, Vol. 11, pp. 148-164, April 15, 1971
This article describes the overall teletype configuration that lias
been developed to support the ground communications require-
ments established for the Mariner Mars 1971 missions. Primary
emphasis is placed on the worldwide distribution of mission traffic
formatted in the teletype discipline, routed through the communi-
cations switching facilities, and provided to various analysis and
control centers.
BOURKE, R. D.
B14 Mariner Mission to Venus and Mercury in 1973
R. D. Bourke and J. G. Beerer
Astronaut. Aeronaut, Vol. 8, No, 1, pp. 52-59, January 1971
The year 1973 presents an unusual opportunity to fly a single
spacecraft to both Venus and Mercury. The Mariner Venus-
Mercury 1973 Project, under which the spacecraft is being devel-
oped, has the following objectives;
(1) To conduct exploratory investigations of Venus and Mercury,
measuring environmental, atmospheric, surface, and body
characteristics. First priority is assigned to the Mercury in-
vestigations.
151
(2) To perform experiments in the interplanetary medium and to
obtain experience with a dual-planet gravity-assist mission.
The project, being managed by JPL, is still in its early stages,
with many key aspects of the mission yet to be decided. This
article describes the preliminary mission planning phase, includ-
ing the background of the project, the characteristics of the 1973
opportunity, and some possible mission options being considered.
FPZIETON, R. G.
lie Lu na r Traverse iM issions
R. G. Brereton, J. D. Burke, R. B. Coryell, and L. D. Jaffe
JPL Quarterly Technical Review, Vol. 1, No. 1, pp. 125-137,
April 1971
The results of recent JPL studies on Lunar Traverse Missions are
compared with the announced characteristics of the Soviet Lun-
okhod 1 rover, delivered to the Moon by the Luna 17 spacecraft
in November 1970. Except for some differences in emphasis among
the scientific experiments, the Lunokhod mission is quite similar
to those recommended in the JPL studies.
FR.i IKMANN, R. T.
f 1£ Electron Impact Excitation of Na
R. T. Brinkmann and S. Trajmar
Ann. Geophys., Vol. 26, No. 1, pp. 201-207,
January-March 1970
An experimental and theoretical study has been made of the ex-
citation of molecular nitrogen under electron bombardment. Dif-
ferential electron impact energy-loss spectra were obtained at
scattering angles from to 80 deg; incident energies of 15, 20, 30,
60, and 80 eV; and the entire possible energy-loss range. Resolu-
tion was typically 0.10 eV. The resulting cross-sections have been
put on an absolute scale by normalizing to known cross-sections.
Empirical and theoretical extrapolations have been made for
higher incident energies. A computer program was written which
uses the Monte Carlo method to calculate the energy deposited
in the various states as a function of incident energy and distance
from the source. If branching ratios and quenching efficiencies
are assumed, the resultant emission intensities are readily calcu-
lated. Illustrative results are presented for 100-eV incident elec-
152
trons, this energy being intermediate between typical auroral and
airglow cases of interest.
BRYAN, A.
B17 DSN [Deep Space Network] Progress Report for
January-February 1971:
DSIF Uplink Amplitude Instability Measurement
A. Bryan and G. Osborn
Technical Report 32-1526, Vol. II, pp. 165-168, April 15, 1971
A simple and inexpensive upper-bound technique for the mea-
surement of Deep Space Instrumentation Facility (DSIF) effective
radiated power is described. Test results verify the theoretical
model and imply that DSIF uplink stability can satisfy Pioneer
F/G attitude-control requirements.
BURKE, J. D.
B18 Lunar Traverse Missions
R. G. Brereton, J. D. Burke, R. B. Coryell, and L. D. Jaffe
JPL Quarterly Technical Review, Vol. 1, No. 1, pp. 125-137,
April 1971
For abstract, see Brereton, R. G.
BUTCHER, L
B19 DSN [Deep Space Network] Progress Report for
January-February 1971:
Tracking and Data System Near-Earth Telemetry
Automatic Switching Unit
L. Butcher
Technical Report 32-1526, Vol. II, pp. 136-139, April 15, 1971
A hardware-software system is described that is capable of select-
ing the best data stream from among as many as six incoming
data streams and switching it automatically to the Deep Space
Instrumentation Facility (DSIF) telemetry system. The system
has been implemented at the Cape Kennedy Compatibility Test
Station to provide the best spacecraft telemetry stream to the
DSIF telemetry system during the near-earth phase of a ti'acking
mission, when as many as six Air Force Eastern Test Range sta-
tions are receiving spacecraft telemetry.
153
BUTMAN, S.
B20 Interplex Modulation
S. Butrnan and U. Timor
JPL Quarterly Technical Review, Vol. 1, No. 1, pp. 97-105,
April 1971
In a conventional phase-shift-keyed/phase-modulated (PSK/PM)
system, the receiver tracks the frequency and phase of the carrier
by means of a phase-locked loop and coherently demodulates the
data. However, due to the inherent nonlinearity of the phase-
modulation process, some power is transmitted as cross modula-
tion, v/hich reduces the useful available power. This article
describes a new PSK/PM modulation scheme, called Interplex,
which reduces the cross-modulation power loss. The scheme can
be implemented in existing systems without significant hardware
changes and appears attractive in concept for improving the per-
formance of deep space telecommunications systems.
B21 Rate Distortion Over Band-Limited Feedback Channels
S. Butrnan
IEEE Trans. Inform. Theor., Vol. IT-17, No. 1, pp. 110-112,
January 1971
Although linear feedback is by itself sufficient to achieve capacity
of an additive gaussian white noise (AGWN) channel, it can not,
in general, achieve the theoretical minimum mean-squared error
for analog gaussian data. This article gives the necessary and
sufficient conditions under which this optimum performance can
be achieved.
lUTTERWORTH, L. W.
122 Structural Analysis of Silicon Solar Arrays
L. W. Butterworth and R. K. Yasui
Technical Report 32-1528, May 15, 1971
This report on the structural design of solar arrays includes dis-
cussions on thermal stresses in array components, mechanical
stresses in solar arrays, analysis of a stress relief interconnect, and
current material properties. Special emphasis has been placed on
developing simple but accurate methods of analysis that will be
of use to the designer.
154
CAMERON, R. E.
COl Growth of Bacteria in Soils from Antarctic Dry Valleys
R. E. Cameron and E. L. Merek (NASA)
Technical Report 32-1522, February 1, 1971
This report presents the results of a study of microbial response
in four cold desert surface soils following moist soil incubation.
Soils were typical Antarctic dry valley saline sands, low in organic
matter content and low in abundances and kinds of viable micro-
organisms. Moist soil incubation increased the viable counts of
three of the four soils. Most of the bacteria could grow at tem-
peratures of 8°C; however, they grew more rapidly at 25 °C. Fail-
ure of isolants from three of the soils to grow in sea salts medium
indicated that they were probably not marine contaminants. It
is suggested that the organisms in the three soils are probably
indigenous organisms. They have adapted to the cold desert
Antarctic terrestrial ecosystem, which provides a soil microbial
ecology as a Mars model.
C02 Survival of Antarctic Desert Soil Bacteria Exposed to Various
Temperatures and to Three Years of Continuous Medium-High
Vacuum
R. E. Cameron and H. P. Conrow
Technical Report 32-1524, February 1, 1971
Samples of cold desert soil containing viable bacteria from Mc-
Kelvey Dry Valley, Southern Victoria Land, Antarctica, were sub-
jected to 3 years of continuous medium-high vacuum of 10"^ to
10-" torr at room temperature and storage for 4 years at —30, —5,
and +20°C. Dependent upon storage temperatures, the surviv-
ability of bacteria decreased with increase in temperatures, with
only 3 bacteria/g of soil surviving at room temperature in vacuum
and 500 bacteria/g of soil surviving storage at — 30°C. Coryne-
bacterium sp., a soil diphtheroid, constituted approximately 90%
of the surviving populations. Arthrobacter spp. and a Micrococcus
sp. also survived, but no Bacillus spp. survived in any of the
samples, although they were present in the soil when it was cul-
tured soon after collection. The reduction in abundance and kinds
of bacteria from this naturally harsh terrestrial environment is
relevant to the importance of storage conditions for return of
Martian soil samples. Based upon Antarctic soil microbial ecology
as a Mars model, the most likely life forms for a Martian cold
desert soil ecosystem are diphtheroid-like microorganisms.
155
COS Microbial and Ecological Investigations of Recent Cinder Cones,
Deception Island, Antarctica— A Preliminary Report
R. E. Cameron and R. E. Benoit (Virginia Polyteciinic Institute)
Ecology, Vol. 51, No. 5, pp. 802-809, Late Sunnmer 1970
Cinder cones that arose during December 1967 within Telefon
Bay, Deception Island, Antarctica, were investigated 1 yr later to
determine the establishment of microorganisms and cryptogams.
Culture media were inoculated to determine the presence and
abundance of algae, fungi, and heteorotrophic, chemoautotrophic,
aerobic, microaerophilic, and anaerobic bacteria. No mosses or
lichens had become established on the cones. Algae, fungi, and
bacteria were generally most abundant around fumaroles emit-
ting moisture and CO,. Several samples contained few or no cul-
turable microorganisms. "Soil" properties of coarse-textured, rela-
tively unweathered acid volcanic materials were unfavorable for
growth, despite the presence of moisture. Microorganisms were
identified from the cinder cones and included primarily soil diph-
theroids and Bacillus spp., Chlorococcum humicola, and Penicil-
lium spp. Most of the bacteria could grow at 2°C as well as at
20°C. '
CANNON, W.
C04 Electric Space Potential in a Cesium Thermionic Diode
K. Shirnada and W. Cannon
Technical Memorandum 33-480, IViarch 31, 1971
For abstract, see Shimada, K.
CERINI, D.J.
COS Liquid-Metal MHD Power Conversion
D. J. Cerini
JPL Quarterly Technical Review, Vol. 1, No. 1, pp. 64-67,
April 1971
A liquid-metal magnetohydrodynamic (MHD) power converter
has been successfully operated with the generation of ac electrical
power. Gaseous nitrogen is used to produce the closed-cycle flow
of the liquid-metal (NaK) working fluid through the MHD gen-
erator where the fluid kinetic energy is converted to electrical
energy. In this article the operational characteristics of the con-
156
verier are given and the results of the current series of tests are
discussed.
CHAO, C. C.
C06 DSN [Deep Space Network] Progress Report for
March-April 1971:
An Additional Effect of Tropospheric Refraction on the Radio
Tracking of Near-Earth Spacecraft at Low Elevation Angles
C. C. Chao and T. D. Moyer
Technical Report 32-1526, Vol. Ill, pp. 63-70,
June 15, 1971
The current tropospheric calibration in the Double Precision
Orbit Determination Program assumes that the direction of the
ray path after it exits from the troposphere is parallel to the true
line-of-sight. Such an assumption will induce a sizable error for
near-earth tracking at low elevation angles. This article examines
such effects and gives additional corrections to the present tropo-
spheric calibration for near-earth tracking.
CHEN, C.J.
CO? Pumping Mechanism of CO2 Laser and Formation Rate of
CO2 From CO and
C.J. Chen
J. Appl. Phys., Vol. 42, No. 3, pp. 1016-1020, March 1, 1971
The pumping mechanism of a high-current-pulsed CO2 laser has
been investigated. It was found that there is a time delay of the
laser pulse behind the current pulse. From the dependence of the
time delay on the plasma parameters, such as electron density,
electron temperature, gas temperature, gas pressure, and emission
of oxygen atomic line (7771 A), it can be shown that, during the
current pulse, the COo is totally dissociated into CO and O. The
subsequent recombinations of CO and O into CO, are responsible
for the pumping of the upper level of the CO2 laser (10.6 and
9.4 fji). The time delay between the current pulse and laser pulse
is thought to be due to the time required for CO and O to recom-
bine to reach the threshold population for lasing for the particular
optical cavity. The threshold upper level population is obtained
by knowing the Q value of the optical cavity, wavelength of the
laser line, and linewidth of the radiation line. By equating the
amount of CO2 formed during the delay time to the threshold
157
upper laser population, the reaction rate of C0 + 0^>C02 is thus
obtained. The agreement between the rate obtained and that pre-
viously determined supports the proposed pumping mechanism.
CLELAND, E. L.
COS Measured Performance of Silicon Solar Cell Assemblies
Designed for Use at High Solar Intensities
R. G. Ross, Jr., R. K. Yasui, W. Jaworski,
L. C. Wen, and E. L Cleland
Technical Memorandum 33-473, March 15, 1971
For abstract, see Ross, R. G., Jr.
COLLINS, S. A.
C09 Photometric Properties of the Mariner Cameras and of
Selected Regions on Mars
A. T. Young and S. A. Collins
J. Gecphys. Res., Vol. 76, No. 2, pp. 432-437,
January 10, 1971
For abstract, see Young, A. T.
CIO Maximum Discriminability Versions of the Near-Encounter
Mariner Pictures
J. A. Dunne, W. D. Stromberg, R. M. Ruiz, S. A. Collins,
and T. E. Thorpe
J. Geophys. Res., Vol. 76, No. 2, pp. 438-472,
January 10, 1971
For abstract, see Dunne, J. A.
CON ROW, H. P.
CI 1 Syrvival of Antarctic Desert Soil Bacteria Exposed to
Various Temperatures and to Three Years of
Continuous Medium-High Vacuum
R. E. Cameron and H. P. Conrow
Technical Report 32-1524, February 1, 1971
For abstract, see Cameron, R. E.
158
COOPER, M. A.
C12 A Detailed Evaluation of the Dependence of 3J(H— H) on Bond
Angle in Alkenes and Cycloalkenes
M. A. Cooper and S. L. Manatt
Org. Mag. Reson., Vol. 2, No. 5, pp. 511-525, October 1970
Newly determined and accurate data for the magnitudes of cis
vinyl proton-proton spin-spin coupling constants in cis-
dialkylethylenes and cycloalkenes have been obtained. With these
new data and also values taken from the recent literature, it has
proved possible to make a critical determination of the correlation
between ^/(H — H) and C^C — H bond angles in ethylenic sys-
tems. It is suggested that it is possible to obtain accurate estimates
of bond angles using nuclear-magnetic-resonance coupling con-
stants, even though much more data will be required to fully sub-
stantiate this proposal. Whereas cz,?-^7(H — H) decreases rapidly
with increasing C=C — H bond angles, evidence is presented that
the opposite is the case for trans-^J(H — H). A brief theoretical
discussion of these trends in coupling constants is given.
CORYELL, R. B.
C13 Lunar Traverse Missions
R. G. Brereton, J. D. Burke, R. B. Coryell, and L. D. Jaffa
JPL Quarterly Techn/ca/ Review, Vol. 1, No. 1, pp. 125-137,
April 1971
For abstract, see Brereton, R. G.
CROW, R. B.
C14 DSN Progress Report for January-February 1971:
Coherent Reference Generator for DSN Mark III Data System
R. B. Crow
Technical Report 32-1526, Vol. II, pp. 133-135, April 15, 1971
A new frequency generator/distribution subsystem is being devel-
oped to meet the increasing complexity of the Deep Space Net-
work (DSN) Mark III data system. The coherent reference gen-
erator is an assembly that will accept the primary frequency
standard from the hydrogen maser ( or possible secondary stand-
ard from the rubidium, cesium, or remote standards) and furnish
required reference frequencies for a deep space station. Prelim-
inary design information and specifications for the coherent refer-
ence generator are given and discussed.
159
CUDDIHY, E. F.
C15 Fatigue of Teflon Bladder Bag Materials
E. F. Cuddihy
JPL Quarterly Technical Review, Vol. 1, No. 1, pp. 57-63,
April 1971
A correlation between fatigue and stress-strain behavior of Teflon
materials was observed during a study of the fatigue properties
of liquid propellant expulsion Teflon bladder bag materials. This
correlation requires only the knowledge of the ultimate breaking
stress of the materials in order to obtain an estimate of the fatigue
properties, and permits a rapid assessment of the expected fatigue
behavior of candidate materials for bladder bags from only a
comparison of their ultimate breaking stress. The general prin-
ciples of this method of fatigue analysis is discussed, along with
the recognition that this technique should have general applica-
tion for other polymeric materials where stress-strain behavior is
comparable to Teflon.
CUFFEL, R. F.
C16 Static Pressure Measurements Near an Oblique Shock Wave
L. H. Back and R. F. Cuffel
AIAA J., Vol. 9, No. 2, pp. 345-347, February 1971
For abstract, see Back, L. H.
C17 Fiow Coefficients for Supersonic Nozzles With Comparatively
Small Radius of Curvature Throats
L. H. Back and R. F. Cuffel
J. Spacecraft Rockets, Vol. 8, No. 2, pp. 196-198,
February 1971
For abstract, see Back, L. H.
CUMMING, W. D.
CIS The Conformational Preferences of the N-Trimethylsityl and
0-TrimethylsiIyl Groups
J. P. Hardy and W. D. Gumming
J. Am. Chem. Soc, Vol. 93, No. 4, pp. 928-932,
February 24, 1971
For abstract, see Hardy, J. P.
160
CURKENDALL, D. W.
C19 DSN [Deep Space Network] Progress Report for
March-April 1971:
A First-Order Theory for Use in Investigating the Informatior
Content Contained in a Few Days of Radio Tracking Data
V. J. Ondrasik and D. W. Curkendail
Technical Report 32-1526, Vol. Ill, pp. 77-93,
June 15, 1971
For abstract, see Ondrasik, V. J.
CUTTS, J. A.
C20 The Surface of Mars: Pt. 1. Cratered Terrains
B. C. Murray (California Institute of Teclinology),
L. A. Soderblom (California Institute of Teciinology),
R. P. Siiarp (California Institute of Teciinology), and
J. A. Cutts (California Institute of Technology)
J. Geophys. Res., Vol. 76, No. 2, pp. 313-330,
January 10, 1971
For abstract, see Murray, B. C.
C21 The Surface of Mars: Pt. 2. Uncratered Terrains
R. P. Sharp (California Institute of Technology),
L. A. Soderblom (California Institute of Technology),
B. C. Murray (California Institute of Technology), and
J. A. Cutts (California Institute of Technology)
J. Geophys. Res., Vol. 76, No. 2, pp. 331-342,
January 10, 1971
For abstract, see Sharp, R. P.
C22 The Surface of Mars: R. 3. Light and Dark Markings
J. A. Cutts (California Institute of Technology),
L. A. Soderblom (California Institute of Technology),
R. P. Sharp (California Institute of Technology),
B. A. Smith (California Institute of Technology), and
B. C. Murray (California Institute of Technology)
J. Geophys. Res., Vol. 76, No. 2, pp. 343-356,
January 10, 1971
As discussed in this article, pictures taken by the Mariner VI and
VII spacecraft have provided significant clues to the nature of the
light and dark markings on Mars, but do not yet provide an ade-
161
quate foundation for any complete explanation of the phenomena.
They display detail never before seen or photographed and dem-
onstrate that there is no network of dark lines (i.e., canals) on the
planet. A variety of shapes and of boundaries between major
markings are recorded in the pictures. No substantial correlation
of albedo markings with cratered or chaotic terrain has been
recognized; featureless terrain conceivably may be genetically
related to light areas. Within and surrounding the dark area
Meridiani Sinus, there is evidence of local topographic control of
albedo markings; light material is found in locally low areas. Also,
characteristic patterns of local albedo markings are exhibited by
craters tliere. Aeolian transportation of light material with depo-
sition locally in low areas is suggested as an explanation of these
markings and may be useful as a working hypothesis for sub-
sequent exploration. Across some light/dark boundaries, crater
morphologies are unchanged; across others, craters in the light
area appear smoother. If there is a relationship between cratered-
terrain modification and surface albedo, it is an indirect one.
C23 The Surface of Mars: Pt. 4. South Polar Cap
R. P. Sharp (California institute of Teciinology),
B. C. Murray (California Institute of Technology),
R. B. Leighton (California Institute of Technology),
L. A. Soderblom (California Institute of Technology), and
J. A. Cutts (California Institute of Technology)
J. Geophys. Res., Vol. 76, No. 2, pp. 357-368, January 10, 1971
For abstract, see Sharp, R. P.
C24 Mercator Photomap of Mars
J. A. Cutts (California Institute of Technology),
G. E. Danielson, Jr., and M. E. Davies (Rand Corporation)
J. Geophys. Res., Vol. 76, No. 2, pp. 369-372, January 10, 1971
Television images of Mars obtained by high-resolution cameras
on the Mariner VI and VII spacecraft have been converted to a
photographic likeness of the planet in the Mercator projection by
the use of computer image-processing techniques. Areodetic posi-
tions of features are established using the Mariner VI and VII
control net. The representation, termed here a Mercator photo-
map, provides an authentic rendition of complex and subtle mark-
ings. The photomap and the techniques used in its development,
as described in this article, have applications to the study of the
seasonal variations on Mars, an objective of the Mariner Mars
1971 orbiter television experiment.
162
DANIELSON, G. E., JR.
DOl Mercator Photomap of Mars
J. A. Cutts (California Institute of Technology),
G. E. Danielson, Jr., and M. E. Davies (Rand Corporation)
J. Geophys. Res., Vol. 76, No. 2, pp. 359-372, January 10, 1971
For abstract, see Cutts, J. A.
D02 Calibration of the Mariner Mars 1969 Television Cameras
G. E. Danielson, Jr., and D. R. Montgomery
J. Geophys. Res., Vol. 75, No. 2, pp. 418-431, January 10, 1971
The purpose of an iBstrument calibration is to determine, as
accurately as possible, the relationship between the input stimulus
and the instrument's output signal. Each individual instrument
has a unique calibration signature that must be accurately deter-
mined, in addition to its behavior characteristics in the environ-
ment in which it is predicted to operate. The philosophy adopted
for calibration of the Mariner Mars 1969 television system was
derived from the basic purpose of exploratory photography, as
established by prior lunar and planetary missions, "to produce
the most accurate and complete reproductions possible of the
observed scenes, consistent with specific objectives and limitations
of the particular experiment." This article presents a description
of the Mariner Mars 1969 two-camera television system, follow-
ing by discussions of the system, component, subsystem, and
thermal-vacuum calibrations that were performed
DAVIES, M. E.
DOS Mercator Photomap of Mars
J. A. Cutts (California Institute of Technology),
G. E. Danielson, Jr., and M. E. Davies (Rand Corporation)
J. Geophys. Res., Vol. 76, No. 2, pp. 359-372, January 10, 1971
For abstract, see Cutts, J. A.
D04 A Preliminary Control Net of Mars
M. E. Davies (Rand Corporation) and R. A. Berg (USAF
Aeronautical Chart and Information Center)
J. Geophys. Res., Vol. 75, No. 2, pp. 373-393, January 10, 1971
163
A control net for Mars has been computed from measurements of
112 points identified on the Mariner VI and VII pictures, and
areocentric coordinates of these points are presented. The coor-
dinates of an initial point are determined, and the near-encounter
frames of Mariner VI and the adjoining near-encounter frames of
Mariner VII are tied to this initial point; then, the far-encounter
pictures of Mariners VI and VII are joined to the near-encounter
pictures. The near-encounter Mariner VII polar pass is located
without reference to the far-encounter frames.
DA¥IS, J. P.
DOS Thermionic Reactor Ion Propulsion Spacecraft for Unmanned
Outer Planet Exploration
J. F. ivlondt and J. P. Davis
J. Spacecraft Rockets, Vol. 8, No. 3, pp. 295-297, March 1971
For abstract, see Mondt, J. F.
DEO, N.
DOS An Extensive English Language Bibliography on Graph Theory
and Its Applications
N. Deo
Technical Report 32-1413, Supplement 1, April 15, 1971
This report is a supplement to the original bibliography of linear
graph theory and its applications that was published in October
1969. Most of the 841 entries in this supplement have appeared
in the past two years. Some are papers that were overlooked in
the original report. Dissertations or internal reports that were
listed in the original bibliography but have since been published
in Journals are listed. Again, only those sources that are pub-
lished in the English language (originally or in translation) are
listed. Unpublished works, private communications, and technical
reports not generally available have been omitted.
DETWEILER, HI. K.
D07 Calculation of Space-Charge Forces in the Analysis of
Traveling-Wave Tubes ■
H. K. Detweiler
JPL Quarterly Technical Review, Vol. 1, No. 1, pp. 106-115,
April 1971
164
A comprehensive large-signal traveling-wave tube computer pro-
gram has been developed for the study and design optimization
of high-efficiency space-type tubes. Studies have been made pre-
viously with a theory which employs a "deformable-disk model"
(DDM) for the electron beam, but neglects EF space-charge
forces in the beam. That theory was found to yield accurate pre-
dictions for tubes in which RF space-charge forces are not the
predominant factor in determining device performance. However,
RF space-charge effects can be very important in tubes designed
for space flight applications. Thus, it is essential to include tliem
in the computer calculations if accurate predictions of device per-
formance are to be obtained. Expressions for the space-charge
fields, appropriate to the DDM representation of the electron
beam, are presented in this article and the methods used in the
calculations are described.
DEVINE, C. J.
DOS On the Computation of Debye Functions of Integer Orders
E. W. Ngand C.J. Devine
Math. Comp., Vol. 24, No. 110, pp. 405-407, April 1970
For abstract, see Ng, E. W.
DUNNE, J. A.
DOB Digital Processing of the Manner 6 and 7 Pictures
T. C. Rindfleisch, J. A. Dunne, H. J. Frieden, W. D. Stromberg,
and R. M. Ruiz
J. Geophys. Res., Vol. 76, No. 2, pp. 394-417,
January 10, 1971
For abstract, see Rindfleisch, T. C.
DIO Maximum Discriminability Versions of the Near-Encounter
Mariner Pictures
J. A. Dunne, W. D. Stromberg, R. M. Ruiz, S. A. Collins,
and T. E. Thorpe
J. Geophys. Res., Vol. 76, No. 2, pp. 438-472,
January 10, 1971
Algorithms for the removal of various types of noises and for en-
hancement of some contrast and resolution were applied to the
Mariner VI and VII composite analog video data to produce pic-
tures optimal for the recognition of fine-scale surface features on
165
Mars. A set of these pictures is presented, along with a brief dis-
cussion identifying the types of processing procedures required
to generate them.
EDMUNDS, R. S.
EOl Development of a Strapdown Electrically Suspended
Gyro Aerospace Navigation System: Final Report
G. Paine, R. S. Edmunds, and B. S. Markiewcz
Technical Mennorandunn 33-471, April 1, 1971 (Confidential)
For abstract, see Paine, G.
EiSENBERGER, I.
E02 DSN [Deep Space Network] Progress Report for
March-April 1971:
Estimating the Parameters of the Distribution of a Mixture of
Two Poisson Populations
I. Eisenberger
Technical Report 32-1526, Vol. Ill, pp. 94-97, June 15, 1971
This article considers the problem of estimating the parameters
of the distribution of a mixture of two Poisson populations. If a
random variable is such that, with probability p, it comes from
a Poisson distributed population with parameter yi and, with
probability (1 — p), it comes from a Foisson-distributed popula-
tion with parameter y^, its density function is given by
pyy^ + {l- p)yle~''-^
g(^) = ^! > X = 0,1,2, ■ • ■
The problem of estimating p, yi, and y2 is considered with respect
to a Deep Space Instrumentation Facility application involving
certain types of equipment for which the density function of time
to failure obeys the exponential law.
ELLEilAN, D. D.
E03 Relative Rates and Their Dependence on Kinetic Energy for
Ion-Molecule Reactions in Ammonia
W. T. Huntress, Jr., M. M. Mosesman, and D. D. Elleman
J. Chem. Phys., Vol. 54, No. 3, pp. 843-849, February 1, 1971
For abstract, see Huntress, W. T., Jr.
166
ESHLEMAN, V. R.
E04 The Neutral Atmosphere of Venus as Studied With the
Mariner V Radio Occultation Experiments
G. Fjeldbo, A. J. Kliore, and V. R. Eshleman (Stanford
University)
Astron. J., Vol. 76, No. 2, pp. 123-140, March 1971
For abstract, see Fjeldbo, G.
FANALE, F. P.
FOl Potassium-Uranium Systematics of Apollo 11 and Apollo 12
Samples: Implications for Lunar Materia! History
F. P. Fanale and D. B. Nash
Science, Vol. 171, No. 3969, pp. 282-284, January 22, 1971
Apollo 11 and 12 lunar rock suites differ in their potassium-
uranium abundance systematics. This difference iadicates that
relatively little exchange of regolith material has occurred be-
tween Mare Tranquillitatis and Oceanus Procellarum. The two,
suites appear to have been derived from materials of identical
potassium and xiranium content. It appears unlikely that bulk
lunar material has the ratio of potassium to uranium found in
chrondrites. However, systematic differences in the potassium-
uranium ratio between Apollo samples and crustal rocks of the
earth do not preclude a common potassium-uranium ratio for
bulk earth and lunar material.
FINNEGAN, E. J.
F02 DSN [Deep Space Network] Progress Report for
March-April 1971:
A New High-Voltage Crowbar
E. J. Finnegan
Technical Report 32-1526, Vol. Ill, pp. 145-148,
June 15, 1971
A crowbar is described which is capable of holding off very high
voltage, 80 kV or greater, using two or more mercury-pool igni-
trons connected in series. This system will replace a single high-
voltage ignitron which has required lengthy processing prior to
use and which failed to stand off voltages above 70 kV. It was
necessary to perfect a higher voltage device in order to improve
the reliability of the crowbar used to protect the high-powered
(high voltage) klystron from self -destructive arcs. An experimental
167
version of the crowbar was built and operated. Also an experi-
mental photon generator, using a light-emitting diode and fiber
optics and a silicon-controlled rectifier with which to pulse the
ignitrcn, was built and tested. Test results are presented, and the
performance has been essentially as predicted. The device will be
used on the 400-kW transmitting subsystem.
FINNIE, C.
F03 DSN [Deep Space Network] Progress Report for
January-February 1971:
Design of Hydrogen Maser Cavity Tuning Servo
C. Finnie
Technical Report 32-1525, Vol. II, pp. 86-88, April 15, 1971
The design of the hydrogen maser cavity tuning servo continues
to be considered. In this article, the servo design details are de-
scribed for a prototype hydrogen maser cavity tuner for use with
the hydrogen maser frequency standards developed at JPL.
FJELDBO, G.
F04 The Neutral Atmosphere of Venus as Studied With the
Mariner V Radio Occultation Experiments
G. Fjeidbo, A. J. Kliore, and V. R. Eshleman (Stanford
University)
Astron^ J., Vol. 76, No. 2, pp. 123-140, March 1971
The Mariner V radio occultation measurements at 423.3 and 2297
MHz (S band) are used to derive profiles in height of refractivity,
molecular number density, pressure, temperature, and dispersive
radio-frequency absorption for the atmosphere of Venus. The
measurements cover heights between about 90 and 35 km (above
a reference surface at a radius of 6050 km), over a pressure range
from about 4 X 10-* to 7 atm. Results obtained on the day and
night sides are remarkably similar. The 90- to 60-km region con-
tains inversion and thermal layers with the minimum temperature
being at least as low as 180 K. The average temperature lapse
rate is 4 K/km between 80 and 60 km. From 60 to 50 km the
lapse rate is about 10 K/km, equal to the dry adiabatic rate for
CO2. No radio absorption was observed above 50 km. In the
50- to 35-km height region, the lower-frequency signal was not
absorbed, but the S-band signal suffered an approximately con-
stant loss of 4 X 10-^ dB per kilometer of propagation path. As-
suming that the agent causing the microwave loss has negligible
refractivity, there is a minimum in the temperature lapse rate
168
between 50 and 45 km altitude. Below this transition region, the
atmosphere may be shghtly superadiabatic with the temperature
reaching approximately 500 K at the lowest level of measurement.
The temperature and microwave loss profiles suggest the presence
of two different cloud systems separated in altitude by about
10 km.
FLANAGAN, F. Wl.
F05 Deep Space Network Support of the Manned Space Flight
Network for Apollo: 1969-1970
F. M. Flanagan, R. B. Hartley, and N. A. Renzetti
Technical Memorandum 33-452, Vol. II, May 1, 1971
This memorandum summarizes the Deep Space Network (DSN)
activities in support of the Apollo Project during 1969 and 1970.
Beginning with the Apollo 9 mission and concluding with the
Apollo 13 mission, the narrative includes mission descriptions,
NASA support requirements placed on the DSN, and compre-
hensive accounts of the support activities provided by each com-
mitted DSN deep space communication station. Associated equip-
ment and activities of the three elements of the DSN (i.e., the
Deep Space Instrumentation Facility, the Space Flight Oper-
ations Facihty, and the Ground Communications Facility) in
meeting the radio-metric and telemetry demands of the missions
are documented. Recent scientific and engineering developments
and plans that will have a direct effect on future DSN Apollo
support plans are also discussed.
FLEISCHER, G. E.
F06 Multi-Rigid-Body Attitude Dynamics Simulation
G. E. Fleischer
Technical Report 32-1516, February 15, 1971
The results of attempts to put into practice the apparent advan-
tages of the "barycenter formulation" of rigid-body rotational
dynamics are described. The end product is a FORTRAN sub-
routine capable of computing the angular accelerations of each
body in a system composed of several point-connected rigid
bodies.
A 3-body system is used to illustrate the concept of the connec-
tion barycenter. Extension of the barycenter formulation of the
dynamical equations to the general case of n bodies is then de-
rived. Some discussion is devoted to the computational problem
of handling interbody torques of constraint. An efficient proce-
169
dure for accommodating the presence of symmetric rotors in the
system is also developed.
Two space vehicle attitude dynamics and control simulations of
some interest are used to illustrate the application of the com-
puter subroutine MLTBDY: one example is a spacecraft, under
three-axis control, subject to the perturbations of a mechanically
scarming platform, while the other is a rigid space vehicle hinged
to four large solar-cell panels and under the influence of a
trajectory-correcting rocket engine.
FOSTER, C. F.
F07 DSN [Deep Space Network] Progress Report for
March-April 1971:
S-Band Demodulator
C. F. Foster
Technical Report 32-1526, Vol. Ill, pp. 149-153,
June 15, 1971
This article describes a portable S-band demodulator. The de-
modulator is a first-order phase-locked loop designed to work
directly with the nominal levels out of the Deep Space Instru-
mentation Facility exciter and/or transmitter. This demodulator
provides an independent means for verification of the exciter/
transmitter performance. Its primary utilization is the measure-
ment of exciter/transmitter amplitude stability, short-term phase
stabilit}', modulation index, bandpass, and modulation fidelity.
FOX, K.
Comment on: "On the Validity of Converting Sums to Integrals
in Quantum Statistical Mechanics" [C. Stutz, Am. J. Phys.,
¥oL 36, No. 9, pp. 826-829, September 1968]
K. Fox
Am. J. Phys., Vol. 39, No. 1, pp. 116-117, January 1971
In the referenced document, Stutz discussed conditions sufficient
to ensure that the conversion of a sum to an integral was valid.
The author concurs with Stutz's feeling that such conversions may
seem mysterious to the uninitiated and hereby points out that
Stutz's results are simply a direct consequence of well-known
formulas in the theory of theta functions. This theory has been
treated in detail in the literature, and its relationship to Stutz's
results is summarized here.
170
F09 Simple Approximate Eigenfunctions for an Electron in a Finite
Dipole Field
K. Fox
Phys. Rev., Pt. A: Gen. Phys., Vol. 3, No. 1, pp. 13-15,
January 1971
Ground-state energy eigenvalues for an electron in a stationary
finite electric-dipole field are calculated by a novel variational
approach. The physical model is taken to be a perturbed hydro-
gen atom. Accurate energy eigenvalues are obtained for a large
range of dipole moments. The simple variational functions used
compare favorably with more nearly exact eigenfunctions ob-
tained in complex calculations.
FRIEDEN, H. J.
FIO Digital Processing of the Manner 6 and 7 Pictures
T. C. Rindfleisch, J. A. Dunne, H. J. Frieden, W. ID. Stromberg,
and R. M. Ruiz
J. Geophys. Res., Vol. 76, No. 2, pp. 394-417,
January 10, 1971
For abstract, see Rindfleisch, T. C.
FYMAT, A. L.
Fll Effect of Absorption on Scattering by Planetary Atmospheres
A. L. Fymat and K. D. Abhyankar
J. Geophys. Res., Vol. 76, No. 3, pp. 732-735,
January 20, 1971
Discrepancies between observed and theoretical values of intensity
and polarization of light scattered by planetary atmospheres are
usually attributed to Mie scattering by aerosols. It is shown that
absorption by molecules or aerosols or both is another important
contributor to such deviations.
GARY, B.
GOl Circular-Polarization and Total-Flux Measurements of Jypiter
at 13.1-cm Wavelength
S. Gulkis and B. Gary
Astron. J., Vol. 76, No. 1, pp. 12-16, February 1971
For abstract, see Gulkis, S.
171
GEIGER, P. J.
G02 Measurement of Organic Carbon in Arid Soils Using Hydrogen-
Flame Ionization Detector
P. J. GeigerandJ. P. Hardy
Soil Sci., Vol. Ill, No. 3, pp. 175-181, March 1971
This article discusses the technical feasibility of determining
total organic carbon in soils with the hydrogen-flame ionization
detector. Samples containing small concentrations of organic
carbon are oxidized by one of two methods: hot oxygen if no
appreciable amounts of carbonate are present, or a powdered
chlorate eutectic mixture if carbonate is present. The method is
particularly useful where samples are small and difficult to
obtain, since only a few milligrams are necessary to complete an
analysis. The determination takes but a few minutes. The appa-
ratus can be built in almost any laboratory presently using gas
cliromatography.
GELLER, M.
G03 On Some Indefinite Integrals of Confluent Hypergeometric
Functions
E. W. Ngand M. Geller
J. Res. NBS, Sec. B: Math. Sci., Vol. 74B, No. 2, pp. 85-98,
April-June 1970
For abstract, see Ng, E. W.
GEORGEVIC, R. M.
G04 Simplified Formulae for the Calculation of Perturbations of the
Osculating Orbital Parameters and of the Range Rate of a
Celestial Body
R. IVl. Georgevic
Technical Memorandum 33-481, June 15, 1971
Although the results of the variation-of-parameters method in
celestial mechanics are well-known, the final formulae for the
time variations of the orbital parameters of the instantaneous
osculating conic have, in most cases, quite different forms. There
172
exists a need for a set of final formulae in their siroplest possible
forms when using the variation-of-parameters method to solve
a dynamical problem of close-to-Keplerian motion. A concise
derivation of the simplest possible set of formulae for the
variation-of-parameters method is presented in this memorandum.
Expressions are also presented for the disturbing effects on the
geocentric range and range rate of a celestial body due to any
disturbing force in the sense of a first-order pertuirbation theory.
Lasdy, an attempt is made to replace the mean anomaly as the
sixth orbital parameter by a more convenient variable that asserts
the consistency in the orders of magnitude of all six time vari-
ations of orbital parameters.
GOODWIN, P. S.
G05 DSN Progress Report for January-February 1971:
Helios Mission Support
P. S. Goodwin
Technical Report 32-1526, Vol. II, pp. 18-27, April 15, 1971
This article relates the historical factors that led to the establish-
ment of the Helios Project, a cooperative solar probe between the
Federal Republic of West Germany and the United States. The
project management relationships between the two countries, in-
cluding the role of the Deep Space Network (DSN), are described.
A description of the spacecraft and its telecommimications sub-
system is also given.
GC6 DSN Progress Report for March-April 1971:
He//os Mission Support
P. S. Goodwin
Technical Report 32-1526, Vol. Ill, pp. 20-28,
June 15, 1971
This is the second in a series of articles relating to Project Helios
which, when used in conjunction with the first article, will give
the reader an overall view of the project, its objectives and
organization, and the support to be provided by the Deep Space
Network (DSN). This article treats, in particular, the contem-
plated Helios trajectories. Both the near-earth phase and the deep
173
space phase of the mission are discussed, with particular emphasis
being placed upon the tracking and data acquisition aspects.
Tracking and Data System Support for the Manner Mars 1969
Mission: Planning Phase Through Midcourse Maneuver
N. A. Renzetti, K. W. Linnes, D. L. Gordon, and T. M. Taylor
Technical Memorandum 33-474, Vol. I, May 15, 1971
For abstract, see Renzetti, N. A.
GREENWOOD, R. F.
G08 Results of the 1969 Balloon Flight Solar Cell
Standardization Program
R. F. Greenwood
Technical Report 32-1530, May 1, 1971
High-altitude calibration of solar cells was accomplished during
July and August 1969 with the aid of free-flight balloons. Flights
were conducted to an altitude of 36,576 m (120,000 ft), a 12,192-m
(40,000-ft) altitude increase over the 1968 flights. Solar cells cah-
brated in this manner are recovered and used as intensity refer-
ences in solar simulators and in terrestrial sunlight. Balloon-
calibrated standard solar cells were made available to NASA
centers and other government agencies through a cooperative
effort with JPL.
Comparison of solar cell data taken at altitudes of 24,384 m
(80,000 ft) and 36,576 m (120,000 ft) was made. Solar cells with
altered spectral response characteristics showed an approximate
1% increase in short-circuit current at the higher altitude. Normal,
unaltered solar cells exhibited little, if any, change in output
between the two altitudes.
Attempts to fly radiometers on two separate flights met with only
partial success. The first flight was plagued with instrumentation
troubles; the final flight was cancelled because of balloon damage.
A sky radiation experiment was also conducted as part of the
1969 balloon flights. Results indicate that no sky radiation is
detectable at 36,576 m (120,000 ft) using normal balloon instru-
mentation and telemetry techniques.
174
GULKfS, S.
G09 A Brief Survey of the Outer Planets Jupiter, Saturn, Uranus,
Neptune, Pluto, and Their Satellites
R. L. Newburn, Jr., and S. Gulkis
Technical Report 32-1529, April 15, 1971
For abstract, see Newburn, R. L., Jr.
GIO Circular-Polarization and Total-Flux Measurements of Jypiter
at 13.1-cm Wavelength
S. Gulkis and B. Gary
Astron. J., Vol. 76, No. 1, pp. 12-16, February 1971
Circular-polarization and total-flux measurements of Jupiter at a
wavelength of 13.1 cm were made during April and May 1969
with the 210-ft radio telescope at the Mars Deep Space Station in
California. An upper limit to the net degree of circular |30lariza-
tion of 1 % was established over the longitude range of the obser-
vations, 10-100° and 160-250° System III (1957.0). Total iux
data have been used to derive a magnetosphere rotation period
of 09''55'"29!72±0.11, which is 0.35 s longer than the standard
International Astronomical Union System III (1957.0), The total
flux data define a beaming curve which has north-south sym-
metry about the magnetic equator, whereas the beaming curve
produced from 1964 observations shows an asymmetry.
HAOEK, ¥.
HOI Cell for Measurement of Basic Electrical Properties of
Amorphous and Polycrystalline Materials Under Pressure
V. Hadek
Rev. Sci. Instr., Vol. 42, No. 3, pp. 393-394, March 1971
The most common method of measuring electrical properties of
amorphous and polycrystalline materials is to use samples in the
form of pellets with vacuum-deposited metallic electrodes. Other
techniques (e.g., the anvil technique) yield the resistivity vs
pressure relationship, but the temperature range is limited. This
article describes a simple and accurate instrument by means of
which the resistivity and the Seebeck coefficient can be measured
simultaneously as a function of temperature and pressure. With
the technique described here, the need for pellet preparation and
evaporation of electrode is obviated; also, the measurement of
electrical properties is possible in a broad temperature range
175
much below room temperature. This technique is less time-
consuming and allows close packing of the material and better
contact than that obtained with the pellet technique.
HAFNER, F. Vll.
H02 Compyfer Controlled Operating and Data Handling
System for a Quadrupole Mass Spectrometer
J. Houseman and F. W. Hafner
Technical Report 32-1518 (Reprinted from J. Phys., Pt E;
Sci. Instr., Vol. 4, No. 1, pp. 46-50, January 1971)
For abstract, see Houseman, J.
HANSELMAN, R. G.
H03 DSN Progress Report for January-February 1971:
GCF Reconfiguration of the Goldstone DSCC Microwave
Terminals for 50-kbit Data Transmission
R. G. Hanselman
Technical Report 32-1526, Vol. II, pp. 129-132, April 15, 1971
The Ground Communications Facility (GCF) functional design
for 1971-1972 specifies two 50-kbit/s data streams between the
Deep Space Network (DSN) Space Flight Operations Facility
and DSS 14 (Mars Deep Space Station), one stream being a
backup to the other. This article describes the reconfiguration of
the Goldstone Deep Space Communications Complex (DSCC)
microwave terminals required for the transmission of dual
50-kbit/s digital data streams between DSS 14 and the Goldstone
DSCC area communications terminal located adjacent to DSS 12
(Echo DSS).
HARDY, J, P.
H04 The Conformational Preferences of the N-Trimethylsilyl and
O-Trirnethyfsilyl Groups
J. P. Hardy and W. D. Cumming
J. Am, Chem. Soc, Vol. 93, No. 4, pp. 928-932,
February 24, 1971
0-Trimethylsilylcyclohexanol (I) and N-trimethylsilylcyclohexyla-
mine (II) and the cis- and *ran5-4-m ethyl and cis- and trans-4-tert-
butyl derivatives of these molecules have been synthesized.
Measurements at 100 and 220 MHz of the nuclear-magnetic-
175
resonance chemical shifts of the a protons of the unsiibstituted
and cis- and ^rans-4-fenf-butyI-substituted compounds were used
to obtain values of 1.21 and 0.88 kcal/mol for the conformational
free energy preferences (A values) of the -NHSiMcs and -OSlMcs
groups, respectively. In addition, A values of 1.15 and 0,93 kcal/
mol, respectively, for these same groups were estimated from the
chemical shift data for the cis-4-methyl compounds, assuming an
A value of 1.70 kcal/mol for the methyl group. The close agree-
ment between these two methods suggests that, in the present
case at least, accurate measurement of conformational prefer-
ences may be obtained by the chemical shift method. The present
results are discussed in light of recent criticism of this method.
An unusually large value for an HCNH proton-proton coupling
of 10 Hz was observed for II.
H05 Photocatalytic Production of Organic Compounds From CO
and H2O in a Simulated Martian Atmosphere
J. S. Hubbard, J. P. Hardy, and N. H. Horowitz
Proc. Nat Acad. So;., Vol. 68, No. 3, pp. 574-578, March 1971
For abstract, see Hubbard, J. S.
H06 Measurement of Organic Carbon in Arid Soils Using Hydrogen-
Flame Ionization Detector
P. J. Geiger and J. P. Hardy
So// So/., Vol. Ill, No. 3, pp. 175-181, March 1971
For abstract, see Geiger, P. J.
HARTLEY, R. B.
H07 DSN Progress Report for January-February 1971:
Apollo Mission Support
R. B. Hartley
Technical Report 32-1526, Vol. II, pp. 33-41, Aprii 15, 1971
The Apollo 14 mission began with launch on January 31, 1971,
and ended with splashdown on February 9. The support provided
by the Deep Space Network (DSN) to the Manned Space Flight
Network (MSFN) during the mission is described. Support was
provided from the three 26-m (85-ft) DSN/MSFN Wing stations,
the Goldstone 64-m (210-ft) antenna, the Ground Communica-
tions Facility, and the Space Flight Operations Facility. Premis-
sion and mission activities are discussed, and the mission is briefly
described.
177
H08 Deep Space Network Support of the Manned Space Flight
Network for Apollo: 1969-1970
F. M. Flanagan, R. B. Hartley, and N. A. Renzetti
Technical Memorandunn 33-452, Vol. II, May 1, 1971
For abstract, see Flanagan, F. M.
HASBACH, W, A.
H09 Lightweight Solar Pane! Development
W. A. Hasbach
Technical Report 32-1519, March 15, 1971
This report describes the work performed by the Boeing Co.,
Aerospace Group, Space Division, Seattle, Washington, between
July 1, 1969, and July 1970, on the Lightweight Solar Panel
Development Program under JPL contract. The report contains
technical information concerning the preliminary design, analysis,
test article design, fabrication, and test of a lightweight solar
panel made of a built-up beryllium structure with an active cell
area o£ 29 ft^. Evaluations are presented of the results of the
modal survey, reverberant acoustic, random vibration, sinusoidal
vibration, static load, thermal-vacuum-shock, substrate fre-
quency, and power output tests.
HIO Design and Development of a 66-W/kg, 23-m2 Roll-Up
Solar Array
W. A. Hasbach
JPL Quarterly Technical Review, Vol. 1, No. 1, pp. 68-77,
April 1971
Future space missions will require greater power output, lighter
weight, and decreased stowed volume for solar arrays. To meet
these requirements, a program was initiated to develop the tech-
nology for a roll-up solar array by preparing a detailed design,
performing the associated analyses, fabricating an engineering
development model, and subjecting the engineering model to a
comprehensive test program consisting of both environmental and
developmental tests. The design and testing of the 66-W/kg
(30-W/lb), 23-m^ (250 ft') roll-up solar array developed during
this program is described in this article.
178
HONG, J. P.
mi A Multiclass Sequential Hypothesis Test With Applications in
Pattern Recognition
J. P. Hong
Technical Memorandum 33-482, June 15, 1971
This memorandum presents an algorithm that can be used to
build a reading machine that will read impact printed characters
and handwritten letters. Invariant features are extracted by
random lines. The number of intersections and the total length
of intersection that these lines produce are the random variable
observations used as inputs to a hypothesis test. This method
allows the pattern to be anywhere in the retina and eliminates
the cost of fine alignment of the pattern before taking samples.
The use of the whole probability distribution of the random
variable allows the introduction of size invariant methods.
The sequential multiclass hypothesis test that is presented is
Wald's sequential probability ratio test for the two-class problem.
The form of this test allows rapid computation of the errors of
the first and second kinds for each possible decision. Extensive
experiments with block letters and handwritten numerals that
verify the usefulness of the proposed test are reported. These
experiments show that the error rates are under the control of
the user and that the average length of the test can be predicted.
HOROWITZ, N. H.
H12 Photocatalytic Production of Organic Compounds From CO
and H2O in a Simulated Martian Atmosphere
J. S. Hubbard, J. P. Hardy, and N. H. Horowitz
Proc. Nat Acad. Sci., Vol. 68, No. 3, pp. 574-578, March 1971
For abstract, see Hubbard, J. S.
HORSEWOOD, J. L
H13 Characteristics, Capabilities, and Costs of Solar Electric
Spacecraft for Planetary Missions
D. R. Bartz and J. L. Horsewood (Analytical Mechanics
Associates, Inc.)
J. Spacecraft Rockets, Vol. 7, No. 12, pp. 1379-1390,
December 1970
For abstract, see Bartz, D. R.
179
hCT;TON, T. E.
■>! 14 Shock-Tube Thermochemistry Tables for High-Temperature
Gases: Carbon Dioxide
W. A. Menard and T. E. Horton
Technical Report 32-1408, Vol. V, March 15, 1971
For abstract, see Menard, W. A.
HOUSEMAN, J.
H15 Computer Controlled Operating and Data Handling
System for a Quadrupole Mass Spectrometer
J. Houseman and F. W. Hafner
Technical Report 32-1518 (Reprinted from J. Phys., Pt E:
Sci. Instr., Vol. 4, No. 1, pp. 46-50, January 1971)
A computer-controlled operating and data handling system for a
quadrupole mass spectrometer is described in this report. The
overall system carries out on-line chemical analyses of combus-
tion gases in a rocket chamber.
The computer-controlled mode of operation is based on supply-
ing the quadrupole control console with an externally generated
control voltage to tune the instrument to the mass numbers that
are of interest. In this manner, only the peak heights of the mass
numbers of interest need to be recorded, rather than a complete
spectrum.
The operation consists of a calibration phase and a run phase.
In the calibration phase, the exact control voltages for all mass
numbers are determined. The control voltages drift with time,
and, in the run phase, nine slightly different values are supplied
around the calibrated control voltage to ensure that the peak is
not missed. Thus, only nine data points are recorded for each
preselected mass number. Immediately after each test series, a
snapshot dump of one scan is printed out in the test area. The
quadrupole output is recorded on digital tape and subsequently
processed by an IBM 7094 computer to yield the relative concen-
trations of the desired components.
The system described here can be used in any application where
the fast scanning capability of the quadrupole is of interest.
HUBBARD, J. S.
H16 Photocatalytic Production of Organic Compounds From CO
and H2O in a Simulated Martian Atmosphere
J. S. Hubbard, J. P. Hardy, and N. H. Horowitz
180
Proc. Nat. Acad. Sci., Vol. 68, No. 3, pp. 574-578, March 1971
[^^CJCOa and [^"'CJorganic compounds are formed when a mix-
ture of ["C]CO and water vapor diluted in [^-CJCO, or N, is
irradiated with ultraviolet light in the presence of soil or pulver-
ized vycor substratum. The [^*C]C02 is recoverable from the gas
phase, and the [^*C]organic products, from the substratom. Three
organic products have been tentatively identified as formaldehyde,
acetaldehyde, and glycolic acid. The relative yields of ['*C]C02
and [^*C]organics are wavelength- and surface-dependent. Con-
version of CO to CO2 occurs primarily at wavelengths shorter
than 2000 A, apparently involves the photolysis of water, and is
inhibited by increasing amounts of vycor substratum. Organic
formation occurs over a broad spectral range below 3000 A and
increases with increasing amounts of substratum. It is suggested
that organic synthesis results from adsorption of CO and ILO on
surfaces, with excitation of one or both molecules occurring at
wavelengths longer than those absorbed by the free gases. This
process may occur on Mars and may have been important on the
primitive earth.
HUMPHREY, M. F.
H17 Solid-Propellant Burning-Rate Modification
M. F. Humphrey
JPL Quarterly Technical Review, Vol. 1, No. 1, pp. 29-34,
April 1971
Low acceleration is one of the requirements for solid-propellant
orbit insertion motors for future outer-planet missions. This
article describes the research accomplished in reducing the low-
pressure burning rates of modified solid propellants. Techniques
developed with the saturated hydroxy-terminated polybutadiene
system were successfully applied to the polyether system (JPL
540) and an unsaturated hydroxy-terminated polybutadiene pro-
pellant system. Burning-rate reductions up to 50% were obtained
by the synergistic eflEects of increased oxidizer size, reduction of
iron, and inclusion of flame retardants and endothermic combus-
tion modifiers.
HUNTRESS, W. T., JR.
H18 Relative Rates and Their Dependence on Kinetic Energy for
Ion-Molecule Reactions in Ammonia
W. T. Huntress, Jr., M. M. Mosesman, and D. D. Elleman
J. Chem. Phys., Vol. 54, No. 3, pp. 843-849, February 1, 1971
181
lon-cyclotron-resonance techniques are used to measure the rela-
tive rates and their dependence on kinetic energy for the major
ion-molecule reactions in ammonia. Charge transfer is shown to
compete with proton transfer in the reaction of both NH,* and
NH3+ with ammonia over an energy range from thermal velocities
to 50 eV:
NHs'
''I
NH/ + NH,
7"
K
NH3+ + NH3
NH,^
Ic,
NH/+NH
h
NH3++NH2
The rate for charge transfer increases with increasing kinetic
energy, while the rate for proton transfer decreases with kinetic
energy. At thermal kinetic energies, /c,/l:i = 0.6 and ^3/^3 = 1-0.
Resonant charge transfer from NH3+ was observed only for trans-
lationally excited ions.
hU'fl, W. J.
J-Jii,' DSN [Deep Space Network] Progress Report for
March-April 1971:
A Wideband Digital Pseudo-Gaussian Noise Generator
W.J. Hurd
Technical Report 32-1526, Vol. Ill, pp. 111-115,
June 15, 1971
A digital system has been constructed for the generation of wide-
band gaussian noise with a spectrum which is flat to within ±0.5
clB from to 10 MHz. These characteristics are substantially
better than those of commercially available analog noise gen-
erators, and are required in testing and simulation of wideband
communications systems. The noise is generated by the analog
summation of 30 essentially independent binary waveforms,
clocked at 35 MHz, and low-pass filtered to 10 MHz.
MUTCHISON, R. B.
H20 Radiative Lifetimes of U.V. Multiplets in Atomic Carbon,
Nitrogen and Oxygen
R. B. Hutchison (Northwestern University)
182
J. Quant. Spectrosc. Radiat. Transfer, Vol. 11, No, 1,
pp. 81-91, January 1971
Ten multiplets in the spectral region 916-1742 A of carbon, nitro-
gen, and oxygen have been measured using a modification of the
phase-shift technique. Excitation of the emission was accom-
plished by the impact of 200-eV electrons with molecular gases
containing the atom of interest. The electron beam was sinusoid-
ally modulated at eight, logarithmically spaced, radio frequencies
ranging from 0.55 to 28.0 MHz. The phase delay of the sinusoid-
ally varying photon output was measured by comparison with a
calibrated, variable delay line to determine the radiative lifetimes.
Five of the multiplets were found to exhibit cascading effects,
and corrections for these effects were obtained by the application
of a one-level cascade model. The measured lifetimes ranged from
1.0 to 9.9 ns, with estimated accuracies of 0.4-1.0 ns.
INGHAM, J. D.
101 Cyanate Ion and the Uremic Syndrome
J. D. Ingham
JPL Quarterly Technical Review, Vol. 1, No. 1, pp. 45-48,
April 1971
A critical survey is made of the literature that logically provides
an hypothesis that relates the symptoms of kidney failure (uremic
syndrome) to the presence of cyanate ion derived from metabolic
urea. If the hypothesis can be unequivocally verified, the conse-
quences will provide a solution to the problem of defining the
primary toxic factor in uremia and should lead to substantial
improvements in the available treatment for patients with kidney
failure.
JACKSON, E. B.
JOl DSN Progress Report for March-April 1971;
DSN Research and Technology Support
E. B. Jackson
Technical Report 32-1526, Vol. Ill, pp. 154-158,
June 15, 1971
Major activities in support of the Deep Space Network (DSN)
research and technology program are presented for the last 6 mo.
Work was performed at both the Venus Deep Space Station and
the Microwave Test Facility. Progress and performance sum-
maries are given in the following areas: radiometric observations
(20-25 GHz); pulsars and planetary radar; 26-m antenna upgrade;
183
precision antenna gain measurements; weak source observations;
and radio star observations (Cygnus A); the Mars Deep Space
Station, transmitter rework and testing; transmitter development;
100-kV7 clock synchronization (X-band); switched carrier experi-
ment; 400-kW harmonic filter; dual 20-kW transmitters; hori-
zontal mill installation; clock synchronization transmissions; and
acceptance testing of Deep Space Instrumentation Facility
klystrons.
JAFFE, L. D.
J02 Lunar Traverse Missions
R. G. Brereton, J. D. Burke, R. B. Coryell, and L. D. Jaffe
JPL Quarterly Technical Review, Vol. 1, No. 1, pp. 125-137,
April 1971
For abstract, see Brereton, R. G.
JOS Blowing of Lunar Soil by Apollo 12: Surveyor 3 Evidence
L. D. Jaffe
Science, Vol. 171, No. 3973, pp. 798-799, February 26, 1971
This article presents an analysis of discoloration patterns that
were noted on the Surveyor 3 (Surveyor III) television camera
after the Apollo 12 lunar module had landed nearby. Evidence
indicates that lunar surface particles were eroded and entrained
by lunar module exhaust during the landing and were ejected
almost horizontally at 70 m/s or faster. These particles struck
the Surveyor camera and whitened its surface.
JAWORSKI, W.
J04 lleasyred Performance of Silicon Solar Cell Assemblies
Designed for Use at High Solar Intensities
R. G. Ross, Jr., R. K. Yasui, W. Jaworski, L. C. Wen,
and E. L. Cleiand
Technical Memorandum 33-473, March 15, 1971
For abstract, see Ross, R. G., Jr.
JET PROPULSION LABORATORY
JOS Proceedings of the Third Annual Conference on Effects of
Lithiorn Doping on Silicon Solar Cells (Held at the
Jet Propulsion Laboratory, April 27 and 28, 1970)
184
Jet Propulsion Laboratory
(P. A. Berman and J. Weingart, Editors)
Technical Memorandum 33-467, April 1, 1971
The Third Annual Conference on EflFects of Lithium Doping on
Silicon Solar Cells was. sponsored by JPL to provide a forum for
an in-depth review and discussion of the results of investigations
being carried out by various organizations, under NASA/JPL
sponsorship, as part of the Solar Cell Research and Development
Program. Participating organizations included cell manufacturers
and university and industrial research laboratories. The 15 formal
presentations of the conference and a summary of the proceed-
ings are presented.
JOHNSON, D.
JOS DSN [Deep Space Network] Progress. Report for
March-April 1971:
Level Sets of Real Functions on the Unit Square
D. Johnson and E. Rodemich
Technical Report 32-1526, Vol. Ill, pp. 108-110,
June 15, 1971
The problem of finding a level curve of /, a real-valued con-
tinuous function on the unit square, which joins opposite sides
of the square is investigated. It is shown that while f need not
have such a level curve, it at least always has a level connected
set with the desired property. This problem is connected with
the problem of minimizing the bandwidth of a certain matrix.
KATOW, M. S.
KOI DSN Progress Report for January-February 1971:
Antenna Structures: Evaluation of Field Measurements of
Reflector Distortions
B. Marcus and M. S. Katow
Technical Report 32-1526, Vol. II, pp. 113-121, April 15, 1971
For abstract, see Marcus, B.
KAWANO, K.
K02 DSN [Deep Space Network] Progress Report for
March-April 1971:
SFOF Mark IIIA User Terminal and Display Subsystem Design
K. Kawano
1S5
Technical Report 32-1526, Vol. Ill, pp. 171-174,
June 15, 1971
The user terminal and display subsystem (UTD) provides various
users with the means to communicate with the Central Processing
System in the Space Flight Operations Facility (SFOF). Prints,
plots, alphanumeric, and graphic displays are presented on
various peripheral devices and on digital television. This article
discusses the requirements, design considerations, and imple-
mentation of the UTD.
KIZNER, W.
K03 DSN [Deep Space Network] Progress Report for
January-February 1971:
Optimal Frame Synchronization
W. Kizner
Technical Report 32-1526, Vol. II, pp. 141-144, April 15, 1971
Optimal frame synchronization algorithms are developed that
will reject bad data as well as provide high probabilities for
obtaining correct frame synchronization with data that have an
error rate within the allowable limits specified by the project.
The exact analysis to obtain these probabilities is outlined. Since
the amount of computation to obtain these quantities may be very
large, easily computed approximations are also given.
KLIORIE, A. J.
K04 The Neutral Atmosphere of Venus as Studied With the
Uariner V Radio Occultation Experiments
G. Fjeldbo, A. J. Kliore, and V. R. Eshleman (Stanford
University)
Astron. J., Vol. 76, No. 2, pp. 123-140, March 1971
For abstract, see Fjeldbo, G.
KLOC, I.
105 Mechanical Interaction of a Driven Roller (Wheel) on Soil
Slopes: The Necessary Conditions for an Equilibrium-Velocity
Solution
L Kloc
Technical Memorandum 33-477, R. I, June 15, 1971
The objective of the study reported here was to develop and
provide a better understanding of mobility concepts for soft
186
sloping terrains as applied to lunar roving vehicles. A general
solution is given for the mobility performance problem of a
power-driven rigid cylindrical roller climbing a semi-infinite soft
soil slope with uniform velocity. The roller axle is subjected to
vertical and pull force components. A gravitating, cohesive-
frictional soil is considered. Emphasis is placed on the application
of the solution to lunar and planetary locomotion. The mechanics
of soil-roller interaction is described and solved, considering
both stress and velocity, as a mixed boundary-value problem.
Kotter's quasi-static equilibrium equations are related to a plastic
stress configuration satisfying Shield's velocity conditions along
the characteristic lines. Solutions of the equilibrium equations
yield the driving torque, slip, sinkage, and soil-roller interface
stresses. Driving power requirements and thrust efficiency are
determined.
A general concept of safety factor against immobilization is
introduced. A computer program for the soil-wheel interaction
performance (SWIP) was developed, and limited applications
of this theory to rigid wheel tests on horizontal terrains indicate
very reasonable agreeinent. The method was also applied to the
Apollo and Lunokhod 1 lunar roving vehicle wheels.
Part I of this memorandum presents the basic and necessary
conditions satisfying the limiting equilibrium and velocity equa-
tions. Part II, to be published separately, will provide the con-
cepts of sufficiency asserting the completeness of a given solution
and the computer program.
KNOELL, A. C.
K06 Structural Design and Stress Analysis Program for
Advanced Composite Filament-Wound Axisymmetric Pressyre
Vessels (COMTANK)
A. C. Knoell
Technical Report 32-1531, May 15, 1971
This report describes a computer program (COMTANK) that
enables the user to design and analyze advanced composite
filament-wound axisymmetric pressure vessels. Based on user
input, the program develops a pressure vessel design using
netting analysis theory and then analyzes the design considering
the orthotropic construction of the vessel. The analysis consists
essentially of determining the stress resultants that exist at a
point in the tank wall and then the stresses that exist in each
ply of the laminate at that point.
187
KOLBLY, R. B.
K07 DSiM [Deep Space Network] Progress Report for
March-April 1971:
Switched Carrier Experiments
R. B. Kolbly
Technical Report 32-1526, Vol. Ill, pp. 133-145,
June 15, 1971
This article describes experiments to produce a practical system
for time-sharing a klystron amplifier between two up-link fre-
quencies. Attempts to produce intermodulation products in the
Deep Space Instrumentation Facility (DSIF) receiver passband
and observations on intermodulation products at a DSIF station
(Pioneer Deep Space Station) are described.
KROGH, F. T.
K08 An Integrator Design
F. T. Krogh
Technical Memorandum 33-479, May 15, 1971
The general design of a system of subroutines for solving the
initial value problem in ordinary differential equations is given.
An attempt has been made to design these subroutines in such a
way that they will be easy to use on easy problems and still be
flexible enough to treat any type of initial value problem with a
high degree of efficiency. Emphasis is on the use of these sub-
routines, rather than on the mathematical algorithms, which, at
this time, are not completely specified. Implementation of the
design in FORTRAN IV suffers from deficiencies in the design
of the multiple entry feature provided in some of the current
FORTRAN IV compilers.
LAESER, R. P.
LOl DSN Progress Report for March-April 1971:
Mariner Mars 1971 i\^ission Support
R. P. Leaser
Technical Report 32-1526, Vol. Ill, pp. 29-37, June 15, 1971
Implementation schedule tradeoffs caused the actual Deep
Space Network (DSN) configuration for support of Mariner
Mars 1971 launch/midcourse/cruise to be significantly different
from the original plans. This article describes the actual con-
figuration by network system.
188
LAWSON, D. D.
L02 Estimation of Polymer Molecular Weight via Refractive Index
R. A. Rhein and D. D. Lawson
Chem. Techno!., Vol. 1, No. 2, pp. 122-126, February 1971
For abstract, see Rhein, R. A.
LEACH, G. E.
LOS DSN [Deep Space Network] Progress Report for
March-April 1971:
SFOF Digital Television Computer Subassembly
G. E. Leach
Technical Report 32-1526, Vol. Ill, pp. 175-178,
June 15, 1971
The Space Flight Operations Facility (SFOF) digital television
computer subassembly is part of the digital television assembly.
It provides control functions and interfacing of two IBM 360/75's
to 80 channels of television for real-time display of alphanumeric
and graphic information. The subassembly consists of a dual com-
puter configuration which is utilized in a primary/alternate mode.
This provides the capability for rapid detection and correction of
failures in the mission operations environment.
LEAHEY, C. F.
L04 DSN Progress Report for January-February 1971:
Mark IIIA Simulation Center Interactive Alphanumeric
Television System
C. F. Leahey
Technical Report 32-1526, Vol. II, pp. 100-107, April 15, 1971
The Deep Space Network (DSN) Mark IIIA Simulation Center is
capable of simultaneously simulating two spacecraft and three
deep space stations using the Univac 1108 and the EMR 6050
computers. The control consoles of the Mark II system were
inadequate for controlling a simulation of the size required for
the Mark IIIA system. A new control and display system was
designed using interactive cathode-ray tube data terminals and
high-speed printers. This design upgrades the control and display
system for future use in more complex missions. Development,
capabilities, and operation of this system are described.
189
XIGHTON, R. B.
The Mariner 6 and 7 Pictures of Mars: One Year's Processing
and Interpretation— An Overview
R. B. Leighton (California Institute of Technology) and
B. C. Murray (California Institute of Technology)
J. Geophys. Res., Vol. 76, No. 2, pp. 293-296,
January 10, 1971
111 late July and early August 1969, 201 complete television
frames of Mars were returned by Mariners 6 and 7 (Mariners VI
and VII). During the subsequent year, over 3500 different ver-
sions of those frames were generated by computer processing,
involving the production of about 35,000 individual photographic
prints and large amounts of computer printout as well. This ex-
tensive data processing and distribution required the significant
participation of about 15 scientists, engineers, and technicians,
mainly at JPL. During that same year, the processed data were
analyzed and interpreted by approximately 25 scientists and tech-
nicians at six different institutions.
This article introduces a series of articles in this issue that present
most of the scientific findings that accrued during the first year
following the Mariner VI and VII flybys of Mars. The collection
of articles constitutes a final report on the television experiment,
although significant efforts are continuing. The nature of the data
obtained, the results regarding the surface and atmosphere of
Mars, and implications for subsequent Martian exploration are
summarized in this overview.
Mariner Mars 1969: Atmospheric Results
C. B. Leovy (University of Washington), B. A. Smith (New
Mexico State University), A. T. Young, and R. B. Leighton
(California Institute of Technology)
J. Geophys. Res., Vol. 76, No. 2, pp. 297-312,
January 10, 1971
For abstract, see Leovy, C. B.
L07 The Surface of iVlars: Pt. 4. South Polar Cap
R. P. Sharp (California Institute of Technology),
B. C. Murray (California Institute of Technology),
R. B. Leighton (California Institute of Technology),
L. A. Soderblom (California Institute of Technology), and
J. A. Cutts (California Institute of Technology)
190
J. Geophys. Res., Vol. 76, No. 2, pp. 357-368,
January 10, 1971
For abstract, see Sharp, R. P.
LEOVY, C. B.
LOS Mariner Mars 1969: Atmospheric Results
C. B. Leovy (University of Washington), B. A. Smith (New
iVlexico State University), A. T. Young, and R. B. Leighton
(California Institute of Technology)
J. Geophys. Res., Vol. 76, No. 2, pp. 297-312,
January 10, 1971
Results of investigation of probable atmospheric effects appearing
in Mariner Mars 1969 television pictures that have undergone
noise removal and preliminary decalibration are described. Two
distinct types of haze are distinguished: north polar haze, seen
prominently against the face of the planet in blue photographs,
and thin haze, usually identified by its appearance on the limb
and not strongly colored. Thin haze is surprisingly widespread,
particularly in the southern hemisphere. Discrete bright features,
which may be evidence for condensation on the ground or in the
atmosphere, are described. These occur where bright features
have often been seen from earth, in a region where very large
multiple-ringed structures seem to dominate the surface morphol-
ogy. The speculation that these may be evidence for local water-
vapor exchange between ground and atmosphere is raised, and
some constraints on local subsurface water-vapor sources in the
Mars tropics are described. Finally, some implications of the
Mariner Mars 1969 results pertinent to atmospheric exploration
by the Mariner Mars 1971 spacecraft are briefly discussed.
LEVY, R.
L09 DSN [Deep Space Network] Progress Report for
January-February 1971:
A Reanalysis Program for Antenna Member Size Changes
R. Levy
Technical Report 32-1526, Vol. II, pp. 108-112, April 15, 1971
An efiBcient procedure is described for reanalysis of space-truss
structural frameworks. The procedure has been programmed to
operate as a post-processor to determine response changes from
sets of displacements developed for the initial structure by an
191
independent structural analysis system. Examples given show
substantial savings in computation time when operating in con-
junction with the NASTRAN structural analysis system.
.EWICKI, G.
Electrical Characteristics of A!N Insulating Films in the
Thickness Range 40 to 150A
G. Lewicki and J. Maserjian
Met. Trans., Vol. 2, No. 3, pp. 673-676, March 1971
Investigation of the electrical properties of metal-insulator-metal
(MIM) capacitor structures prepared by nitriding freshly de-
posited aluminum films in a nitrogen glow discharge indicates
that insulating films of AIN having thicknesses on the order of
100 A could be useful in charge-storage devices. These films are
sufEciently conductive at high fields to allow charging and dis-
charging of a buried metal gate with relatively low and short
voltage pulses (on the order of 10 V across the AIN for 10"' s or
less) and sufficiently insulating at lower values of electric field to
store this charge for long periods of time. This article discusses
the characteristics relating to steady-state current density, voltage,
and insulator thickness for MIM capacitor structures (Au-AIN-
Al) over the insulator thickness range 50 to 150 A.
I. K.
Passive Damping of the Forced Precession Motion of a
Two-Body Satellite
W. K. Lim
J. Spacecraft Rockets, Vol. 8, No. 1, pp. 41-47, January 1971
The two-body satellite under study consists of two axisymmetric
rigid bodies interconnected by a lossy universal joint that ensures
a common axial spin but dissipates energy when there is lateral
relative motion. The external torque acting on the system is
assumed to be perpendicular to the symmetry axis of one body
and an external fixed direction. This article is concerned with the
analysis and analytical design of this system for fast damping of
its transient oscillations. Two methods have been developed for
the computation of the decay time of the forced precession cone
angle: one is based on energy consideration, and the other, on
angular momentum consideration. The dependences of the decay
time on each of the physical parameters of the system were
investigated. For an especially simple near-optimum configura-
tion, an analytic solution for the decay time was obtained. The
192
newly developed theory was applied in an example to the design
of a small sun-pointing interplanetary probe oriented by a solar
sail.
LINNES, K. W.
L12 DSN Progress Report for March-April 1971:
Radio Science Support
K. W. Linnes, T. Sato, and D. Spitzmesser
Technical Report 32-1526, Vol. Ill, pp. 46-51, June 15, 1971
Since 1967, radio scientists have used the Deep Space Network
(DSN) 26- and 64-m antenna stations to investigate pulsars and
the effects of the solar corona on radio signals. They have also
observed radio emissions of X-ray sources, and have used very
long baseline interferometry techniques for high-resolution stud-
ies of quasars. The various experiments are identified and sum-
marized, and the published results are indicated.
L13 Tracking and Data System Support for the Mariner Mars 1969
Mission: Planning Phase Through Midcourse Maneuver
N. A. Renzetti, K. W. Linnes, D. L. Gordon, and T. M. Tayior
Technical Memorandum 33-474, Vol. I, May 15, 1971
For abstract, see Renzetti, N. A.
LIU, A.
L14 Method of Averages Expansions for Artificial
Satellite Applications
J. Lorell and A. Liu
Technical Report 32-1513, April 1, 1971
For abstract, see Lorell, J.
LOBB, V.
L15 Bolted Joints Under Sustained Loading
V. Lobb and F. Stoller
J. Struct. Div., Proc. ASCE, Vol. 97, No. ST3, pp. 905-933,
March 1971
A study of bolted structural joints under sustained loads (1000 h)
was made to determine long-term joint slip. Joints representative
of antenna structural joints were used. These joints were coated
193
with galvanize, Inorganic Zinc primer, red oxide zinc chromate
primer, and mill scale. Interference bolts and hex-head bolts of
tv/o different grades were used (ASTM A325 and ASTM A490).
The bolted structural joints were tested for long-term static shear
stress, long-term static shear stress with a superimposed trans-
verse vibration, and short-term static shear stress with repetitive
load leversals. The effects of such variables as joint and fastener
coatings, bolt design and strength level shear and tension stress,
and balanced design tension-shear rates were studied. All of the
faying surfaces tested reached a steady-state rate of slip under
sustained loads. The amount and degree of total slip and slip rate
were dependent principally on joint shear stress, faying-surface
coating, and bolt type.
LORELL,
Method of Averages Expansions for Artificial
Satellite Applications
J. Lorell and A. Liu
Technical Report 32-1513, April 1, 1971
Formulas for the averaged potential in artificial satellite theory
are derived. The potential due to gravity harmonics is developed
for the general nm harmonic. That due to a third body is de-
veloped up to the fifth degree in R/Rs, the small distance ratio.
The expressions given differ from ones generally available in the
literature in that they do not depend on expansions in either
eccentricity or inclination.
In addition, a discussion is included on the use of the method of
averages for tesseral harmonics. In the case of the rapidly rotating
planet Mars, the method is constrained to the evaluation of zonal
harmonics. For more slowly rotating bodies such as the moon, all
tesseral harmonics can be included.
..UDWIG, A.
.17 Antenna Support Structure Aperture Blockage Loss
A. Ludwig
JPL Quarterly Technical Review, Vol. 1, No. 1, pp. 86-96,
April 1971
Loss in antenna gain caused by support structure aperture block-
age is probably the most difficult loss factor to measure or calcu-
late. In this article the loss is determined experimentally for
aluminum and fiberglass structural configurations, and empirical
formulas are developed to calculate the loss for other similar
194
configurations. Experimental and analytical data on the X-band
RF transmission characteristics of thin fiberglass sheets are pre-
sented. It is concluded that fiberglass structures are far superior
for minimizing gain loss.
LUSHBAUGH, W.
LIS DSN [Deep Space Network] Progress Report for
January-February 1971:
Information Systems: Hardware Version of an Optimal
Convolutional Decoder
W. Lushbaugh
Technical Report 32-1526, Vol. II, pp. 49-55, April 15, 1971
A hardware version of an optimal convolutional decoder is de-
scribed. This decoder implements the Viterbi algorithiiQ for
maximum-likelihood decoding of short-constraint-length convolu-
tional codes. It is capable of decoding at data rates up to 1 mega-
bit for codes of constraint length 3, 4, or 5 at code rate Vi or V?,.
LUTES, G.
L19 DSN [Deep Space Network] Progress Report for
January-February 1971:
Improved Frequency Dividers
G. Lutes
Technical Report 32-1525, Vol. 11, pp. 56-58, April 15, 1971
Frequency dividers with improved phase stability were recently
developed for use in the hydrogen maser frequency standard.
The commonly used methods of frequency division were found
to have excessive phase noise and long-term drift and would thus
seriously degrade the inherent stability of the frequency standard.
An improvement in phase noise of nearly two orders of magni-
tude is indicated with the improved frequency dividers.
MacFARLANE, M.
MOl High-Dispersion Spectroscopic Observations of Venus:
V. The Carbon Dioxide Band at 8689 k
L. D. G. Young, R. A. J. Schorn, E. S. Barker (University of
Texas), and M. MacFariane (University of Texas)
Icarus: Int. J. Sol. Sys., Vol. 11, No. 3, pp. 390-407,
November 1959
For abstract, see Young, L. D. G.
195
MACLAY, J. E.
M02 DSN Progress Report for January-February 1971:
DSN Operations Control System
J. E. Maclay
Technical Report 32-1526, Vol. II, pp. 4-5, April 15, 1971
A new Deep Space Network (DSN) capability for high-speed
transfer of operational control information has been implemented.
A 24-fold increase in speed is realized by using the high-speed
data line instead of teletype. Automatic inputting of source data
yields an additional increase.
MADRID, G. A.
M03 DSN Progress Report for March-April 1971:
Tracking System Analytic Calibration Support for the
Mariner Mars 1971 Mission
G. A. Madrid
Technical Report 32-1526, Vol. ill, pp. 52-62, June 15, 1971
The means by which calibrations for Deep Space Network (DSN)
tracking data will be provided to the Mariner Mars 1971 Project
is described. The scope and accuracy of calibrations for distinct
error source components is stated and a description of the soft-
ware to compute and provide calibrations for transmission media
and platform observable errors is furnished. Utilization of these
caKbrations will permit the DSN to satisfy the project's naviga-
tional accuracy requirements of 250 km at encounter minus 30
days.
MANATT, S. L.
M04 A Detailed Evaluation of the Dependence of 3J(H— H) on
Bond Angle in Alkenes and Cycloalkenes
M. A. Cooper and S. L. Manatt
Org. Mag. Reson., Vol. 2, No. 5, pp. 511-525, October 1970
For abstract, see Cooper, M. A.
MARCUS, B.
M05 DSN Progress Report for January-February 1971:
Antenna Structures: Evaluation of Field Measurements of
Reflector Distortions
B. Marcus and M. S. Katow
Technical Report 32-1526, Vol. II, pp. 113-121, April 15, 1971
196
Field measurements of reflector distortions, using die theodolite
angle differences and fixed arc lengths from the vertex of the
paraboloid, are based on apparent displacements normal to the
line of sight. Two computing methods are described that use
directions information from the structural computer analysis to
upgrade the readings in the pathlength errors sense. Comparative
rms values of the 1/2 pathlength errors, after a paraboloid best fit,
that result from the field measurements, the analytical analysis,
and the rms equivalences to RF radio star measurements are
overlayed on an rms surface tolerance versus elevation angle chart
for the Deep Space Network (DSN) 64-m-diam antenna. Close
rms agreements allow designation of an error tolerance of ±0.08
mm (0.003 in.) for the field-measured rms values.
MARGOLIS, J. S.
M06 Self-Broadened Half-Widths and Pressure Shifts for the
R-Branch J-Manifolds of the Svz Methane Band
J. S. Margolis
J. Quant. Spectrosc. Radiat. Transfer, Vol. 11, No. 1,
pp. 69-73, January 1971
The self -broadening coefficients for the /-manifolds (0 < 7 < 7)
of the R-branch of the Svs band of methane have been measured.
These measurements were performed by comparing synthetic
spectra with variable parameters to the measured ones. Measure-
ments were made over a range of pressures of 500-1500 torr.
Pressure shifts of the components within a /-manifold were also
determined.
MARKIEWCZ, B. S.
M07 Development of a Strapdown Electrically Suspended
Gyro Aerospace Navigation System: Final Report
G. Paine, R. S. Edmunds, and B. S. Markiewcz
Technical IVlemorandum 33-471, April 1, 1971 (Confidential)
For abstract, see Paine, G.
MARSH, H. E., JR.
M08 Oil-Absorbing Polymers
H. E. iVlarsh, Jr.
JPL Quarterly Technical Review, Vol. 1, No. 1, pp. 49-56,
April 1971
197
A new research program has been started to develop technology
needed to make practical use of a well-known characteristic of
elastomeric cross-linked polymers. Such polymers, of which class
modern solid-propellant binders are members, absorb large
amounts of compatible solvents, and yet remain solid. Two goals
are being considered in this program. One goal is a material that
can be used as a dietary additive which will selectively absorb
fats and oils in the digestive tract and hold them until elimina-
tion, thus preventing their assimilation. The other goal is a mate-
rial that can be used in oil-slick mop-up operations. This article
presents the interim results on the formulation and testing of three
polymer types. Performances amounting to oleic acid absorption
of up to 20 times the dry polymer weight have been measured.
Higher values are expected. Both mineral oil and a cooking oil
are also absorbed, but to a smaller extent.
Plasma Properties and Performance of Mercury Ion Thrusters
T. D. Masek
AlAA J., Vol. 9, No. 2, pp. 205-212, February 1971
This article describes: (1) the electron bombardment ion thruster
operation, (2) the relationship of the plasma to this operation,
and (3) a consistent method for computing the discharge power
per beam ion from the plasma properties for comparison with the
measured value. A modified form of the Bohm stable sheath cri-
terion is shown to apply for computing fluxes. The use of this
criterion, along with calculations of ion production rates and
electron fluxes, permits a more accurate and comprehensive pic-
ture or discharge losses than has been obtained previously. Lang-
muir probe measurements in conventional 15- and 20-cm-diam
thrusters using mercury are presented. The 15-cm-diam thruster,
of 1962 vintage, was operated at high flow rates (650-mA equiva-
lent mercury flow rate) for comparison with previous lower flow-
rate data and to establish reference thruster plasma characteristics.
mSERJIAN, J.
110 Electrical Characteristics of AIN Insulating Films in the
Thickness Range 40 to 150A
G. Lewicki and J. Maserjian
Met. Trans., Vol. 2, No. 3, pp. 673-676, March 1971
For abstract, see Lewicki, G.
198
MASON, P. V.
Mil Effect of Tin Additive on Indium Thin-Film Superconducting
Transmission Lines
P. V. Mason
J. Appl. Phys., Vol. 42, No. 1, pp. 97-102, January 1971
The effect of adding up to 23% tin to the indium film of a thin-
film/tantalum-oxide/bulk-tantalum transmission line is described.
Addition of tin reduces the velocity and increases the delay for
fixed length by 1.4% for each percent of tin. Agreement with the
predictions of Pippard's nonlocal theory when mean-free path is
reduced is excellent. Pulse attenuation and shape degradation
are not increased by addition of tin. Attenuation as low as 10 dB
per microsecond of delay was observed at 1.25 K. The added tin
reduces by 50% the sensitivity of velocity to temperature near
the critical temperature and improves the reproducibility of
velocity from line to line. Critical temperature is increased to 6 K
for 23% tin, in good agreement with previous measurements.
McCLURE, J. P.
Mia DSN Progress Report for March-April 1971:
Ground Communications Facility System Tests
D. Nightingale and J. P. McClure
Technical Report 32-1526, Vol. Ill, pp. 190-192,
June 15, 1971
For abstract, see Nightingale, D.
McELIECE, R. J.
MIS DSN [Deep Space Network] Progress Report for
January-February 1971:
The Limits of Minimum Distance Decoding
R. J. McEliece
Technical Report 32-1526, Vol. II, pp. 59-61, Ap'il 15, 1971
Decoding algorithms that are based on the minimum distance of
a block code cannot be used to achieve channel capacity. This
degradation is compared with similar degradation caused by
sequential decoding. The details of the calculations and assump-
tions used in this investigation are presented.
199
DSN [Deep Space Network] Progress Report for
January-February 1971:
Symmetrically Decodable Codes
R. J. McEliece and J. E. Savage (Brown University)
Technical Report 32-1526, Vol. II, pp. 62-64, April 15, 1971
With the intention of finding binary block codes that are easily
decoded, decoding functions consisting of one level of symmetric
functions are examined. It is found that all codes so decodable
with fixed error correction capability t have rate less than
l/{2t + 1) and that this rate is achieved by the repetition code
that has two code words and length 2t + 1. Decoding functions
consisting of two or more levels of symmetric functions include
all binary functions and can therefore decode arbitrarily good
binary codes.
DSN [Deep Space Network] Progress Report for
March-April 1971:
The Problem of Synchronization of Noisy Video
R. J. McEliece
Technical Report 32-1526, Vol. Ill, pp. 105-107,
June 15, 1971
The problem of acquiring and maintaining TV line synchroniza-
tion with the use of a pseudonoise (FN) prefix on each scan line,
in the presence of random noise, is discussed. The currently pro-
posed method of detecting a loss of TV line synchronization on
the Mariner Mercury- Venus flight is to prefix each line with a
31-bit PN sequence, and to assume that a loss of synchronization
lias occurred if the PN appears to have suffered 9 or more bit
errors. At high signal-to-noise ratios, this method behaves satis-
factorily, but at low signal-to-noise ratios, which could occur at
Mercuiy, the PN sequency can actually suffer 9 or more random
bit errors with a significant probability. To reduce this probabil-
ity to acceptable levels, a PN of length 63 is recommended for
use on the Mariner Mercury- Venus flight.
On Periodic Sequences From GF(q)
R. J. McEliece
J. Combin. Theor., Vol. 10, No. 1, pp. 80-91, January 1971
If s{t) ;_s a periodic sequence from GF{q) — F, and if N is the
number of times a non-zero element from F appears in a period
of s, a theorem presented in this article says N ^ O(mod p^),
where e is an integer which depends upon the support of the
200
Fourier transform of s. An easy corollary deals with G(/), the
set of all sequences from F which satisfy the linear recurrence
with characteristic polynomial / e F[x]. It sa5-'S that, for all
s e G(f), N ^ O(mod p^), where now e depends upon the smallest
integer m for which it is possible to write 1 as a product of m
conjugates of roots of f.
Mclaughlin, f. d.
Ml? DSN Progress Report for January-February 1971:
Overseas DSIF 64-m Antenna Project Status
F. D. McLaughlin
Technical Report 32-1526, Vol. II, pp. 177-181, April 15, 1971
The status of construction of two Deep Space Instrumentation
Facility (DSIF), 64-m-diameter, steerable, paraboloid, tracking
antennas being installed near Canberra, Australia, and Madrid,
Spain, is presented. These Deep Space Network (DSN) antennas
are being constructed by the Collins Radio Company, Dallas,
Texas, under JPL contract.
MENARD, W. A.
M18 Shock-Tube Thermochemistry Tables for
High-Temperature Gases: Carbon Dioxide
W. A. Menard and T. E. Horton
Technical Report 32-1408, Vol. V, March 15, 1971
Equilibrium thermodynamic properties and species concentra-
tions for carbon dioxide are tabulated for moving, standing, and
reflected shock waves. Initial pressures range from 6.665 to
6665 N/m^ (0.05 to 50.0 torr), and temperatures from 2,000 to
over 80,000 K. In this study, 20 molecular and atomic species are
considered.
M19 A Higher Performance Electric-Arc-Driven Shock Tube
W. A. Menard
JPL Quarterly Techn/ca/ Review, Vol. 1, No. 1, pp. 17-28,
April 1971
The results of an experimental study to improve the performance
of electric-arc-driven shock tubes are presented. With only minor
modifications to the driver, shock velocities have been increased
by a factor of 3. The new driver has a conical internal design of
small volume and uses a lightweight diaphragm that disintegrates
201
during the electrical discharge. Data obtained from a 15.2-cm-
diameter driven tube, 11.3 m in length, show little shock wave
attenuation in gases simulating the Jupiter and Saturn atmo-
spheres. Shock velocities of 45 km/s with test times in excess of
4 fts have been attained. Because of the extended performance,
the electric-arc-driven shock tube may now be used to study
many outer-planet atmospheric entry problems.
WENNINGER, F.
M20 DSN [Deep Space Network] Progress Report for
March-April 1971:
26-m Antenna HA-dec Counter Torque Modifications
F. Menninger
Technical Report 32-1526, Vol. Ill, pp. 245-247,
June 15, 1971
A servo hydraulic control system is used to control the motion of
the 26-m HA-dec Deep Space Instrumentation Facility antennas.
This article describes the improvement in tracking performance
of the 26-m antenna as a result of changes in the hydraulic
circuit of the HA-dec servo subsystem. A discussion of previous
problem areas and the results of the new modification are stated.
MEREK, E. L.
M21 Grofrth of Bacteria in Soils from Antarctic Dry Valleys
R. E. Cameron and E. L. Merek (NASA)
Technical Report 32-1522, February 1, 1971
For abstract, see Cameron, R. E.
MEYER, R.
M22 DSN [Deep Space Network] Progress Report for
March-April 1971:
Stability Comparison of Three Frequency Synthesizers
R. !Vleye;r
Technical Report 32-1526, Vol. Ill, pp. 98-104, June 15, 1971
The HP 5100A/5110A, Dana 7030, and Fluke 644A synthesizers
were evaluated to determine the typical drift and stability that
can be expected in a control room environment. All synthesizers
were judged equal in short-term drift, and the Dana synthesizer
202
was found to be superior in long-term drift. The HP and the
Dana synthesizers were the most stable, while the Fluke
synthesizers did not perform reliably.
MICCIO, J. A.
M23 DSN Progress Report for January-February 1971:
DSN Traceability and Reporting Program
J. A. Miccio
Technical Report 32-1526, Vol. II, pp. 145-147, April 15, 1971
The Deep Space Network (DSN) Traceability and Reporting Pro-
gram is a combination of three programs designed to coordinate
and disseminate information needed by researchers, analysts, and
managers concerning the DSN mission data record for a current
and/or past mission. It also serves as a monitor or as an account-
ing device by providing status information relative to the genera-
tion of system, master, and experimenter data records. The
program additionally functions as an index to the mission data
captured on magnetic tape and microfilm retained in the DSN
Operational Data Control Center.
MILLER, R. B.
M24 DSN Progress Report for March-April 1971:
Radiometric Data Accountability, Validation, and!
Selection in Real-Time
R. B. Miller
Technical Report 32-1526, Vol. Ill, pp. 219-223,
June 15, 1971
A principal responsibility of the Deep Space Network (DSN)
Tracking System Analysis Group (TRAG) is to provide a source
of validated radiometric data, with all associated information
required for processing, for both flight projects and nonreal-time
data users. This article describes the TRAG design goal for
providing a complete and validated data source with a minimum
of manual intervention. The functions described will be part of
the Mark III A 360/75 tracking software subsystem.
MONDT, J. F.
M25 Thermionic Reactor Ion Propulsion Spacecraft for
Unmanned Outer Planet Exploration
J. F. Mondtand J. P. Davis
J. Spacecraft Rockets, Vol. 8, No. 3, pp. 295-297, March 1971
203
The nuclear thermionic reactor power system is one of the leading
nuclear power system candidates for electric propulsion appli-
cations for unmanned missions to Jupiter, Saturn, Uranus, and
Neptune. This article presents the external-fuel thermionic reac-
tor concept for development of a useful 70-lb/kWe, 70-kWe
electric propulsion system. The side-thrust propulsion system
isolates the science payload from the high temperature, the
nuclear radiation, and the mercury exhaust environments. A
spacecraft arrangement using side-thrust propulsion allows a Air
steradian field of view during the entire mission. The Titan
III-D/Centaur launch vehicle, being developed for other un-
manned missions, has the capability to launch the 70-kWe space-
craft to earth escape velocity.
MONTGOMERY, D. R.
M26 Calibration of the Mariner Mars 1969 Television Cameras
G. E. Danielson, Jr., and D. R. Montgomery
J. Geophys. Res., Vol. 76, No. 2, pp. 418-431,
January 10, 1971
For abstract, see Danielson, G. E., Jr.
MOSESMAN, M. M.
IVI27 Relative Rates and Their Dependence on Kinetic Energy for
Ion-Molecule Reactions in Ammonia
W. T. Huntress, Jr., M. M. Mosesman, and D. D. Elleman
J. Chem. Phys., Vol. 54, No. 3, pp. 843-849, February 1, 1971
For abstract, see Huntress, W. T., Jr.
MOYER, T. D.
M28 DSN [Deep Space Network] Progress Report for
March-April 1971:
An Additional Effect of Tropospheric Refraction on the Radio
Tracking of Near-Earth Spacecraft at Low Elevation Angles
C. C. Chao and T. D. Moyer
Technical Report 32-1526, Vol. Ill, pp. 63-70, June 15, 1971
For abstract, see Chao, C. C.
204
M29 Mathematical Formulation of the Double-Precision
Orbit Determination Program (DPODP)
T. D. Meyer
Technical Report 32-1527, May 15, 1971
This report documents the complete mathematical mode! for the
double-precision orbit determination program (DPODP), a third-
generation program recently completed at JPL. The DPODP
processes earth-based doppler, range, and angular observables of
the spacecraft to determine values of the parameters that specify
the spacecraft trajectory for lunar and planetary missions. The
program was developed from 1964 to 1968; it v^^as first used oper-
ationally for the Mariner VI and VII spacecraft, i^'hich encoun-
tered Mars in August 1969.
The DPODP has more accurate mathematical models, a significant
increase in numerical precision, and more flexibility than the
second-generation single-precision orbit determination program
(SPODP). Doppler and range observables are computed to accu-
racies of 10"° m/s and 0.1 m, respectively, exclusive of errors in
the tropospheric, ionospheric, and space plasma corrections.
MUDGWAY, D. J.
M30 DSN Progress Report for January-February 1971:
Viking Mission Support
D. J. Mudgway
Technical Report 32-1526, Vol. I!, pp. 28-32, April 15, 1971
Two Viking spacecraft, each consisting of an orbiter and a lander,
will be launched on a mission to Mars in 1975. This article dis-
cusses the capabilities of the Deep Space Network (DSN) as
significant factors in the radio frequency and data management
design and the engineering requirements of the two orbiters and
two landers. Also described is the DSN involvemient in the ex-
tremely complex lander acquisition sequence, in which trade-offs
are made between the total lander "on" period of 2 h and com-
peting factors of round-trip light time and telemetry and com-
mand lockup times.
M31 DSN Progress Report for March-April 1971:
Viking Mission Support
D. J. Mudgway
Technical Report 32-1526, Vol. Ill, pp. 38-45, June 15, 1971
205
This article discusses the capabilities of the Deep Space Network
(DSN) as a factor in the design of the Viking telecommunications
system. The problem of accommodating simultaneous downlinks
from two orbiters and one lander with dual uplinks to one orbiter
and oae lander or two orbiters is discussed. Because the Viking
encounter and subsequent orbital and landed operations take
place near maximum earth-Mars separation (approximately
400 X 10" km), the signal-to-noise ratios on both up and down-
links are minimal to support the extensive command and data
retrieval requirements. The tradeoflFs between DSN capabilities
and project reqtiirements such as these are described in the
context of the mission design.
lULHOLLAND, J. D.
132 The System of Planetary Masses as Error Sources in
Pulsar Timings
J. D. Mulholland
Astrophys. J., Vol. 165, No. 1, R. 1, pp. 105-107,
April 1, 1971
Studies of the intrinsic variation of pulsar frequencies, related to
the search for understanding of the physical processes occurring
within these objects and to the search for planetary companions,
require the reduction of the observations to the barycenter of
the solar system. Uncertainties in planetary data will introduce
corresponding uncertainties into the pulsar observations. The
system of planetary masses, which presents such an error source,
is shown to introduce potentially observable effects, but with
sufficiently small rates as to represent nearly constant biases over
extended periods of time. These effects could be misidentified as
evidences of planetary companions, but can have no effect on
the value of the braking parameter.
\Y, B. C.
The Manner 6 and 7 Pictures of Mars: One Year's Processing
and Interpretation— An Overview
R. B. Leighton (California Institute of Technology) and
B. C. Murray (California Institute of Technology)
J. Geophys. Res., Vol. 76, No. 2, pp. 293-296,
January 10, 1971
For abstract, see Leighton, R. B.
206
M34 The Surface of Mars: Pt. 1. Cratered Terrains
, B. C. Murray (California Institute of Technology),
L. A. Soderblom (California Institute of Technology),
R. P. Sharp (California Institute of Technology), and
J. A. Cutts (California Institute of Technology)
J. Geophys. Res., Vol. 76, No. 2, pp. 313-330,
January 10, 1971
As described in this article, the pictures taken during the Mariner
VI and VII missions show that craters are the dominant landforna
on Mars and that their occurrence is not correlated uniquely with
latitude, elevation, or albedo markings. Two distinct morpholog-
ical classes are recognized: small bowl-shaped and large flat-
bottomed. The former show little evidence of modifications,
whereas the latter appear generally more modified than lunar
upland craters of comparable size. A regional maria/uplands
dichotomy like the moon has not yet been recognized on Mars.
Crater modification on Mars has involved much greater horizontal
redistribution of material than that in the lunar uplands. It is
possible that there are erosional processes only infrequently ac-
tive. Analysis of the natures and fluxes of bodies that have prob-
ably impacted the moon and Mars leads to the conclusion that it
is likely that most of the large flat-bottomed craters on Mars have
survived from the final phases of planetary accretion. Significant
crater modification, however, has taken place more recently on
Mars. Inasmuch as the present small bowl-shaped craters evi-
dence little modification, the postaccretion crater-modification
process on Mars may have been primarily episodic rather than
continuous. The size-frequency distribution of impacting bodies
that produced the present small Martian bowl-shaped craters
differs from the distribution of impacting bodies that produced
the post-mare primary impacts on the moon by a marked defi-
ciency of large bodies. Survival of crater topography from the end
of planetary accretion would make any hypothetical earthlike
phase with primitive oceans there unlikely. The traditional view
of Mars as an earthlike planetary neighbor in terms of its surface
history is not supported by the picture data.
M35 The Surface of Mars: Pt. 2. Uncratered Terrains
R. P. Sharp (California Institute of Technology),
L. A. Soderblom (California Institute of Technology),
B. C. Murray (California Institute of Technology), and
J, A. Cutts (California Institute of Technology)
J. Geophys. Res., Vol. 75, No. 2, pp. 331-342,
January 10, 1971
For abstract, see Sharp, R. P.
207
136 The Surface of Mars: Pt. 3. Light and Dark Markings
J. A. Cutts (California Institute of Teclnnology),
L. A. Soderblom (California Institute of Technology),
R. P. Sharp (California institute of Technology),
B. A. Smith (California Institute of Technology), and
B. C. Murray (California Institute of Technology)
J. Geophys. Res., Vol. 76, No. 2, pp. 343-356,
January 10, 1971
For abstract, see Cutts, J. A.
137 The Surface of Mars: Pt. 4. South Polar Cap
R. P. Sharp (California Institute of Technology),
B. C. Murray (California Institute of Technology),
R. B. Leighton (California Institute of Technology),
L. A. Soderblom (California Institute of Technology), and
J. A. Cutts (California Institute of Technology)
J. Geophys. Res., Vol. 76, No. 2, pp. 357-368,
January 10, 1971
For abstract, see Sharp, R. P.
lASH, D. B.
JOl Potassium-Uranium Systematics of Apollo 11 and >^po//o 12
Samples: Implications for Lunar Material History
F, P. Fanale and D. B. Nash
Science, Vol. 171, No. 3969, pp. 282-284, January 22, 1971
For abstract, see Fanale, F. P.
lEWBURN, R„ L, JR.
102 A Brief Survey of the Outer Planets Jupiter, Saturn, Uranus,
Neptune, Pluto, and Their Satellites
R. L. Newburn, Jr., and S. Gull<is
Technical Report 32-1529, April 15, 1971
A survey of current knowledge about Jupiter, Saturn, Uranus,
Neptune, Pluto, and their satellites is presented. The best avail-
able numerical values are given for physical parameters, includ-
ing orbital and body properties, atmospheric composition and
structure, and photometric parameters. The more acceptable
current theories of these bodies are outlined, with thorough
referencing offering access to the details. The survey attempts to
be complete through February 15, 1971.
208
NG, E. W.
N03 On Some Indefinite Integrals of Confluent Hypergeometric
Functions
E. W. Ngand M. Geller
J. Res. NBS, Sec. B: Math. Sci., Vol. 74B, No. 2, pip. 85-98,
April-June 1970
Analytical expressions and reduction formulas are developed for
various indefinite integrals of the confluent hypergeometric func-
tions. These integrals are of the type
/ f{a, b, z)z''e'"dz,
where / is one of the two Kummer functions
M{a, h, z) ^ iFi(c; h; z) or U{a, h, z),
with real or complex a, h, z, and a, and real p.
N04 On the Computation of Debye Functions of Integer Orders
E. W. Ngand C.J. Devine
Math. Comp., Vol. 24, No. 110, pp. 405-407, April 1970
The Debye functions, which occur in thermodynamic problems
in the context of, for example, crystallographic structure or radi-
ation, are sometimes labeled radiation integrals. These functions,
as defined in this article, are essentially incomplete Riemann's
zeta functions. This article presents an efficient method for the
computation of Debye functions of integer orders to 20 significant
decimal digits.
N05 Recursive Algorithms for the Summation of Certain Series
M. M. Saffron and E. W. Ng
SIAMJ. Math. Anal., Vol. 2, No. 1, pp. 31-35, February 1971
For abstract, see Saffren, M. M.
NIGHTINGALE, D.
N06 DSN Progress Report for March-April 1971:
Ground Communications Facility System Tests
D. Nightingale and J. P. McClure
Technical Report 32-1526, Vol. II!, pp. 190-192,
June 15, 1971
The Ground Communications Facility substantially upgraded
the High-Speed System and implemented a new Wideband
209
System for more comprehensive operational data transfers. Exten-
sive tests were conducted prior to turning these systems over to
operations personnel for integration into the Deep Space Net-
work (DSN). This article summarizes the purpose and results
of these tests, with the final objective of full committed support
of Mariner Mars 1971 flight operations.
OAKLEY, E. C.
DSN [Deep Space Network] Progress Report for
March-April 1971:
Digital Step Attenuator
E. C. Oakley
Technical Report 32-1526, Vol. ill, pp. 211-214,
June 15, 1971
A 50-O digital step attenuator has been developed having 0.2-dB
resolution and 51-dB maximum loss. This device has been tested
from dc to 10 MHz, where a ±5-deg maximum dififerential phase
shift was measured. Preliminary tests indicate that the attenuator
may operate satisfactorily at frequencies as high as 100 MHz.
No signal discontinuity occurs during switching, and positive
confirmation of step activation is provided. The attenuator is
constructed on a 14.5 by 3.2-cm (5.7 by 1.25-in.) double-sided
etched circuit card, and occupies a volume of less than 74 cm^
(4.5 iii.=).
OLWER, R. E.
002 Large Spacecraft Antennas: New Geometric Configuration
Design Concepts
R. E. Oliver
JPL Quarterly Techr)ical Review, Vol. 1, No. 1, pp. 78-85,
April 1971
Several unconventional approaches to the configurational design
of high-gain microwave antenna reflectors are presented. These
approaches provide means for improving the performance of non-
furlable antennas and for improving both aperture efficiency and
stowed volume efficiency of furlable antennas.
The first class of design approaches involves relatively minor
modifications of conventional dual-reflector (Cassegrain and Gre-
gorian feed) antenna concepts. These modifications eliminate the
loss of transmitted energy resulting from the reflection of energy
210
back into the feed from the subreflector as well as the loss due to
interception of rays by the subreflector after reflection from the
main reflector.
The second class of concepts involves the use of a conical main
reflector and multiple reflections from this main reflector and
from one or more subreflectors. These concepts ofl:er the advan-
tage of relative ease of fabrication, inspection, and furlability as-
sociated with a single curvature (conical) main reflector. In addi-
tion, they provide configurations with very small diameter sub-
reflectors, resulting in low aperture area blockage and small
furled antenna diameters.
ONDRASIK, V. J.
003 DSN [Deep Space Network] Progress Report for
March-April 1971:
A First-Order Theory for Use in Investigating the Information
Content Contained in a Few Days of Radio Tracking Data
V. J. Ondrasik and D. W. Curkendall
Technical Report 32-1526, Vol. Ill, pp. 77-93, June 15, 1971
An approximation to the topocentric range rate of a spacecraft
is developed which is first order in both the time past epoch and
the ratio between the distance of an observing station from the
geocenter and the geocentric range. This approximation is com-
pared with a numerical integrated trajectory to obtain some
idea of the duration over which it may be reliable. The develop-
ment is extended to include an analytical determination of the
errors in the spacecraft state produced by errors in the range
rate data. It is also shown how range data may be incorporated
into this cursory error analysis. The partial derivatives of the
gravitational geocentric acceleration vwth respect to range,
declination, and right ascension are obtained analytically and
shown graphically.
OSBORN, G.
004 DSN [Deep Space Network] Progress Report for Janyary-
February 1971:
DSIF Uplink Amplitude Instability Measurement
A. Bryan and G. Osborn
Technical Report 32-1526, Vol. II, pp. 165-168, April 15, 1971
For abstract, see Bryan, A.
211
OTOSHI, T. Y.
005 DSN [Deep Space Network] Progress Report for January-
February 1971:
A Study of Microwave Transmission Through Perforated Flat
Plates
T. Y. Otoshi
Technical Report 32-1526, Vol. II, pp. 80-85, April 15, 1971
This article presents a simple formula and graph useful for pre-
dicting the transmission loss of a circular hole array in a metallic
flat plate having either a 60- (staggered) or 90-deg (square) hole
pattern. The formula is restricted to the case of an obliquely in-
cident plane wave with the E-field polarized normal to the plane
of incidence. The theoretical formula was experimentally verified
by testing samples having hole diameters varying from 1.6 to 12.7
mm, porosities varying from 10 to 51%, and plate thicknesses
varying from 0.08 to 2.3 mm. The agreement between theory and
experiment was typically better than 1 dB at S-band and 2 dB at
X-band.
006 DSN [Deep Space Network] Progress Report for
March-April 1971:
Analysis of the Boresight Error Calibration Procedure
for Compact Rotary Vane Attenuators
T. Y. Otoshi
Technical Report 32-1526, Vol. ill, pp. 126-132,
June 15, 1971
In previous studies of the compact rotary vane attenuator, the
possible error due to stator vane misalignment was not con-
sidered. It is shown in this article that even though the stator
vanes are misaligned with respect to each other, the boresight
error calibration procedure will tend to cause the residual
attenuation error to reduce to a type B error which is generally
negligible. This analysis applies to conventional as well as to
compact rotary vane attenuators.
PAINE, G.
POl Development of a Strapdown Electrically Suspended Gyro
Aerospace Navigation System: Final Report
G. Paine, R. S. Edmunds, and B. 8. Markiewcz
Technical Memorandum 33-471, April 1, 1971 (Confidential)
The Strapdown Electrically Suspended Gyro Aerospace Navigator
(SEAN) is a developmental inertial system conceived in 1965. The
212
SEAN development program at JPL has proven the feasibility of
employing electrically suspended gyros (ESGs) in a strapdown
inertial navigation system with a high angular rate environment.
Methods for accurately calibrating a strapdov/n ESG have also
been demonstrated. This memorandum provides the objectives,
accomplishments, recommendations, and conclusions of the pro-
gram. Those areas requiring further development work to produce
an operational system are detailed. A brief functional description
of the system developed to prove the feasibility of an ESG strap-
down navigator is also included.
PAINE, R. A.
P02 DSN Progress Report for January-February 1971:
SFOF Cable Control
R. A. Paine
Technical Report 32-1526, Vol. II, pp. 122-124, April 15, 1971
The Space Flight Operations Facility (SFOF) experiences frequent
reconfigurations in both its physical layout and its functional capa-
bilities. These changes are necessary to meet new requirements
placed on it by the Deep Space Network (DSN) and the flight
projects. This article summarizes a cabling plan that maintains
discipline in the installation and removal of cabling in the SFOF.
PENZO, P. A.
P03 Satellite Flyby Opportunities for the Multi-Outer-Planet
Missions
P. A. Penzo
JPL Quarterly Technical Review, Vol. 1, No. 1, pp,. 1-12,
April 1971
In the proposed missions to the outer planets, obsei-vations of the
planets' natural satellites will be of considerable scientific interest.
In the study presented in this article, the satellite encounter oppor-
tunities are generated for two multiple-flyby missions which
include all five of the major planets. Many favorable encounter
opportunities are found for the large satellites of Jupiter, and some
for Titan and lapetus of Saturn. The opportunities for satellites of
Uranus are least favorable. Opportunities also exist for multiple-
satellite encounters on the same mission and examples are shown.
Finally, for Jupiter, some arrival dates exist where very close flybys
of certain satellites are possible. These opportunities, added to
the multiple-planet missions, will enhance the scientific return
significantly.
213
PHiLLiPS, H.
P04 DSN [Deep Space Network] Progress Report for
March-April 1971:
Deveiopment of the Heat Exchanger for the 64-m
Antenna Hydrostatic Bearing
H. Phillips
Technical Report 32-1526, Vol. Ill, pp. 193-196,
June 15, 1971
Maintenance of oil temperature, as a means of viscosity control,
is an essential requirement for the 64-m antenna hydrostatic
bearing. Operational experience with the heat exchanger used
for cooling the oil showed that it was not functioning adequately
or in accordance with the design, and a resultant study showed
a probable internal structural failure. A new heat exchanger was
designed, with JPL assistance on the structural problem, and is
now operating satisfactorily.
POWELL, W.B.
P05 Thrust-Chamber Technology for Oxygen Difluoride/Diborane
Propellants
R. W. Riebling and W. B. Powell
J. Spacecraft Rockets, Vol. 8, No. 1, pp. 4-14, January 1971
For abstract, see Riebling, R. W.
RAKUMAS, R. R.
ROl DSN Progress Report for March-April 1971:
DSN Multiple-Mission Command System
R. R. Rakunas and A. Schuize
Technical Report 32-1526, Vol. Ill, pp. 4-6, June 15, 1971
The Deep Space Network (DSN) Multiple-Mission Command
System generates and transmits commands to one or two space-
craft simultaneously from a central location. All commands are
originated at the Space Flight Operations Facility (SFOF) and
can be sent to one or more Deep Space Stations for storage or
transmission to the spacecraft. This article describes the DSN
Multiple-Mission Command System and reflects the functions
of the Deep Space Instrumentation Facility, Ground Communi-
cations Facility, and SFOF elements that support it.
214
REED, I. S.
R02 DSN [Deep Space Network] Progress Report for January-
February 1971:
Boolean Difference Calculus and Fault Finding
I. S. Reed (University of Southern California)
Teclinica! Report 32-1526, Vol. II, pp. 65-71, April 15, 1971
This article describes a method for testing for a possible fault in a
gate in a larger switching circuit. The feature of the method is
that it does not require isolating the suspicious gate from the rest
of the circuit. The techniques involve a Boolean difference calculus
reminiscent of, but not identical to, ordinary difference calculus.
REID, M. S.
R03 DSN Progress Report for January-February 1971:
Improved RF Calibration Techniques: System Operating Noise
Temperature Calibrations
M. S. Reid
Technical Report 32-1526, Vol. II, pp. 89-91, April 15, 1971
The system operating noise temperature performance of the follow-
ing low noise research cones in the Deep Space Network (DSN)
Goldstone Deep Space Communications Complex is reported for
the periods indicated :
(1) S-band polarization ultra cone at DSS 11 (Pioneer Deep Space
Station); October 1970 through January 1971.
(2) S-band research operational cone at DSS 13 (Venus DSS):
October 1970 through January 1971.
(3) Polarization diversity S-band cone at DSS 14 (Mars DSS):
mid-September 1970 through January 1971.
(4) Multi -frequency X-band/K-band cone at DSS 14: mid-March
1970 through February 1971.
The operating noise temperature calibrations were performed
using the ambient termination technique.
REIER, M.
R04 Absolute Gamma-Ray Intensity Measurements of a SNAP-15A
Heat Source
M. Reier
Nud. Sci. Eng., Vol. 43, No. 3, pp. 267-272, March 1971
215
A germanium crystal has been used to measure the absolute inten-
sity of gamma rays from the decay of ^"**Pu, -^-Pb, -^-Bi, and -"'^Tl
in. a 1.5-W SNAP-ISA (System for Nuclear Auxiliary Power ISA)
heat source. In practically all cases, agreement with other measure-
ments is excellent. In addition, the amount of ^aep^ impurity
originally present in the sample can be measured with an accuracy
of 4% . It is estimated that the ^^''Pu content in a fuel sample that
is several months old can easily be measured with an accuracy
of 10%.
lENZETTI, N. A.
105 DSN Progress Report for January-February 1971:
DSN Fynctions and Facilities
N. A. Renzetti
Technical Report 32-1526, Vol. li, pp. 1-3, April 15, 1971
The Deep Space Network (DSN), established by the NASA Office
of Tracking and Data Acquisition and under the system manage-
ment and technical direction of JPL, is designed for two-way
communications with unmanned spacecraft traveling approxi-
mately 16,000 km (10,000 mi) from earth to planetary distances.
The objectives, functions, and organization of the DSN are sum-
marized, and its three facilities — the Deep Space Instrumentation
Facility, the Ground Communications Facility, and the Space
Flight Operations Facility — are described.
106 DSN Progress Report for March-April 1971:
DSN Fuinctions and Facilities
N. A. Renzetti
Technical Report 32-1526, Vol. Ill, pp. 1-3, June 15, 1971
The Deep Space Network (DSN), established by the NASA
Office of Tracking and Data Acquisition and under the system
management and technical direction of JPL, is designed for
two-way communications with unmanned spacecraft traveling
approximately 16,000 km (10,000 mi) from earth to planetary
distances. The objectives, functions, and organization of the
DSN are summarized, and its three facilities — ^the Deep Space
Instrumentation Facility, the Ground Communications Facility,
and the Space Flight Operations Facility — are described.
:07 Tracking and Data System Support for the Pioneer Project:
Pioneer ¥11. Extended Mission:
February 24, 1957-Ju!y 1, 1968
N. A. Renzetti
216
Technical Memorandum 33-426, Vol. VI, April 15, 1971
The Tracking and Data System supported the deep space phase
of the Pioneer VII mission, which is in an outward trajectory from
the earth in a heliocentric orbit. During the period of this memo-
random, six scientific instruments aboard the spacecraft continued
to register information relative to interplanetary particles and
fields, and radio metric data generated by the network continues
to improve our knowledge of the celestial mechanics of the solar
system. In addition to detail network support activities, network
performance and special support activities are covered.
R08 Tracking and Data System Support for the Pioneer Project:
Pioneer ¥11. Extended Mission:
July 1, 1968-July 1, 1959
N. A. Renzetti
Technical Memorandum 33-426, Vol. VII, April 15, 1971
The Pioneer VII mission (outward trajectory, heliocentric orbit)
utilized six scientific instruments to accumulate information rela-
tive to interplanetary high-energy particles, solar phenomena, and
plasma. The spacecraft also served as a celestial mechanics experi-
ment reference point. The Tracking and Data System (comprised
of the Air Force Eastern Test Range, Deep Space Network,
Manned Space Flight Network, and NASA Comm,unications Net-
work) tracked the spacecraft from launch through near-eartli and
deep space phases. For near-earth communications and tracking,
all Tracking and Data System facilities responded to mission,
launch vehicle, and range requirements. For deep space communi-
cations and tracking, the Deep Space Network responded to track-
ing, telemetry, command, monitoring, simulation, and operations
control requirements.
R09 Tracking and Data System Support for the Pioneer Project:
Pioneer VIII. Extended Mission:
June 1, 1968-July 1, 1969
N. A. Renzetti
Technical Memorandum 33-426, Vol. VIII, May 1, 1971
The Pioneer VIII mission (outward trajectory and heliocentric
orbit) employed seven scientific instruments to accumulate infor-
mation relative to interplanetary high-energy particles, solar
phenomena, and plasma. The spacecraft also served as a celestial
mechanics experiment reference point and carried aloft a "piggy-
back" satellite, called the Test and Training Satellite, to be used
for Apollo ground station crew training and mission simulation.
Deep space tracking for the first period of the extended flight phase
217
was made possible by the Deep Space Network, which responded
to all tracking telemetry, command, monitoring, simulation, and
operations control requirements.
Deep Space Network Support of the Manned Space Flight
Network for ^po//o: 1959-1970
F. M. Flanagan, R. B. Hartley, and N. A. Renzetti
Technical Memorandum 33-452, Vol. II, May 1, 1971
For abstract, see Flanagan, F. M.
Tracking and Data System Support for the Mariner Mars 1969
Mission: Planning Phase Through Wlidcourse Maneuver
N. A. Renzetti, K. W. Linnes, D. L. Gordon, and T. M. Taylor
Technical Memorandum 33-474, Vol. I, May 15, 1971
The Tracking and Data System support for the Mariner Mars 1969
Project that is described herein was planned and implemented in
close cooperation with the Mission Operations and Spacecraft
Systems of the project. The project requirements for tracking,
telemetry, command, simulation, mission control, and compati-
bility testing were reviewed for matching to Deep Space Network
(DSN) capabilities. The DSN capabilities to support the project
were set forth in an operations plan describing the design of the
DSN systems formulated for the support of this project. Each of
the systems is described. Unusual new features were the multi-
mission telemetry system, which eliminated the need for mission-
dependent equipment at the tracking stations, and an experimental
liigli-rate telemetry system operating at 16,200 bits/s. This unusu-
ally high rate, employed for the first time in deep space missions,
permitted low-resolution pictures to be returned in real time and
full-resolution pictures to be played back from the spacecraft tape
recorder in less than 3 h. Normal techniques and rates would have
required 7 to 8 days of playback.
Flight support was provided in the near-earth phase by the facili-
ties of the Air Force Eastern Test Range and by the Ascension
Island Station of the Manned Space Flight Network. The 26-m
antenna stations of the DSN provided the deep space phase sup-
port throughout the mission. During the cruise portion of the deep
space phase, the DSN 64-m antenna at the Mars Deep Space
Station in California provided ranging data to planetary distances;
during the planetary encounter, it provided the 16,200-bits/s capa-
bility by means of the block-coded, high-rate telemetry system.
Analysis of the support performance shows that virtually all track-
ing and telemetry data received on earth was acquired, processed.
218
and delivered to the project. All commands delivered to the DSN
by the project for transmission to the spacecraft were ti-aiismitted
successfully.
RHEIN, R.A.
R12 Estimation of Polymer Molecular Weight via Refractive Index
R. A. Rhein and D. D. Lawson
Chem. Techno!., Vol. 1, No. 2, pp. 122-126, February 1971
The number-average molecular weight of polymers is ordinarily
obtained by laborious methods, such as viscosity, osmometry,
light-scattering, and gel permeation chromatography measure-
ments. As discussed in this article, linear correlations, have now
been demonstrated between inverse molecular weight and index of
refraction for isobutylene and ethylene oxide polymers and telom-
ers and for saturated hydrocarbons and nonconjugated dienes.
RIEBLING, R. W.
R13 Thrust-Chamber Technology for Oxygen Difluoricle/Diborane
Propellants
R. W. Riebling and W. B. Powell
J. Spacecraft Rockets, Vol. 8, No. 1, pp. 4-14, January 1971
Analyses of high-launch-energy unmanned outer-planet orbiter
missions for 1970-1985 indicate that payloads probably will be
severely constrained by the capabilities of economical launcli
vehicles. One way to increase the payload is to use high-energy
propellants in the spacecraft propulsion system. System studies
have led to the choice of oxygen difluoride (OF2) and diborane
(BoHe) as a promising candidate propellant combination because
of: (1) the potentially high vacuum specific impulse (approximately
400 s at a thrust chamber expansion area ratio of 60) at a relatively
low chamber pressure of about 100 psia, and (2) a relatively broad
common liquidus range (105°F with a maximum vapor pressure
of 100 psia). (A low chamber pressure is important because liquid
chemical propulsion systems required by unmanned missions en-
visioned for the next decade or so will burn relatively small quanti-
ties of propellant at relatively low thrast levels.) Both constraints
dictate a pressure-fed (low-chamber-pressure) propulsion system,
rather than a pumped (high-chamber-pressure) system.
Such a propulsion system now under development at JPL is being
designed to be capable of operating anywhere between the solar
orbits of Venus and Pluto. This article surveys one aspect of this
program: thrust chamber technology for the OF2/B2H,; propel-
219
laiits. Advanced development of three types of pressure-fed cham-
bers is under way: (1) a film-cooled or mixture-ratio-stratified
chamber made of an advanced carbonaceous or graphitic material,
or possibly a metallic material; (2) a regeneratively cooled metallic
chamber; and (3) a heat-pipe-cooled metallic chamber. It is
planned to select the most promising thrust chamber concept for
final development to flight-prototype status. Revievs^ed here is the
technology effort in the key areas of heat transfer, propellant &ow
characteristics, solids deposition, vacuum ignition behavior, deliv-
ered vacuum performance, and materials development. Other
areas in which further effort appears justified are identified.
IINDFLEISCH, T. C.
114 Digital Processing of the Mariner 6 and 7 Pictures
T. C. F^indfleisch, J. A. Dunne, H. J. Frieden, W. D. Stromberg,
and R„ M. Ruiz
J. Geophys. Res., Vol. 76, No. 2, pp. 394-417,
January 10, 1971
The Mariner Mars 1969 television camera system was a vidicon-
based digital system and included a complex on-board video
encoding and recording scheme. The spacecraft video processing
was designed to maximize the volume of data returned and the
encoded discriminability of the low-contrast surface detail of Mars.
The ground-based photometric reconstruction of the Mariner 6
and 7 (Mariner VI and VII) photographs, as well as the correction
of inherent vidicon camera distortion effects necessary to achieve
television experiment objectives, required use of a digital computer
to process the pictures. The digital techniques developed to recon-
struct the spacecraft encoder effects and to correct for camera
distortions are described, and examples of the processed results
are shown. Specific distortion corrections that are considered
include the removal of structured system noises, the removal of
sensor residual image, the correction of photometric sensitivity
nonuniformities and nonlinearities, the correction of geometric
distortions, and the correction of modulation transfer limitations.
JOBERTSON, F. A.
!15 Low Acceleration Rate Ignition for Spacecraft
J. I. Shafer, L. D. Strand, and F. A. Robertson
JPL Quarterly Technical Review, Vol. 1, No. 1, pp. 35-44,
April 1971
For abstract, see Shafer, J. I.
220
RODEMICH, E.
R16 DSN [Deep Space Network] Progress Report for
March-April 1971:
Level Sets of Real Functions on the Unit Square
D. Johnson and E. Rodennich
Technical Report 32-1526, Vol. Ill, pp. 108-110,
June 15, 1971
For abstract, see Johnson, D.
ROSS, R. G., JR.
R17 Measured Performance of Silicon Solar Cell Assemblies
Designed for Use at High Solar Intensities
R. G. Ross, Jr., R. K. Yasui, W. Jaworski, L C. Wen, and
E. L. Cleland
Technical Memorandum 33-473, March 15, 1971
This memorandum presents the results of an experimental pro-
gram to evaluate the performance of three solar panel design
approaches suitable for use at high solar intensities: the second-
surface mirror mosaic approach, the selective bandpass filter
approach, and the tilted panel approach. Extensive data are pre-
sented on the thermal and electrical characteristics of a number
of specific cell/coverglass assemblies representative of these ap-
proaches. Included are data on electrical performance at intensities
from 1 to 6 suns, data on thermal-optical properties both before
and after long-term ulti^aviolet and proton radiation exposure, and
data on the thermal-mechanical properties of a number of solar
cell adhesives.
RUIZ, R. M.
R18 Digital Processing of the Mariner 6 and 7 Pictures
T. C. Rindfleisch, J. A. Dunne, H. J. Frieden, W. D. Stromberg,
and R. M. Ruiz
J. Geophys. Res., Vol. 76, No. 2, pp. 394-417,
January 10, 1971
For abstract, see Rindfleisch, T. C.
R19 Maximum Discriminability Versions of the Near-Encounter
Mariner Pictures
J. A. Dunne, W. D. Stromberg, R. M. Ruiz, S. A. Collins, and
T. E. Thorpe
221
J. Geophys. Res., Vol. 76, No. 2, pp. 438-472,
January 10, 1971
For abstract, see Dunne, J. A.
RUSCH, W. V. T.
R20 Applications of Two-Dimensionai Integral-Equation
Theory to Reflector-Antenna Analysis
W. V. T. Rusch
Technical Memorandum 33-478, May 15, 1971
The method of moments is applied to the solution of integral equa-
tions for the current induced on conducting cylinders immersed
in an arbitrary two-dimensional field. The solution is outlined,
and such scattering parameters as the induced-field ratio and the
extinction cross section are defined. Numerical solutions are ob-
tained for several geometries that are relevant to the problem of
large reflector antenna analysis.
SAFFREN, M. M.
SOI Recursive Algorithms for the Summation of Certain Series
M. M. Saffren and E. W. Ng
SIAM J. Math. Anal., Vol. 2, No. 1, pp. 31-36, February 1971
In this article, the computation of the series
N
Sy = ^ dnPn
n-0
is studied by regarding it as a solution of an inhomogeneous
difference equation. Since power series are often computed using
first-order difference equations, an analysis for this type of compu-
tation is also presented.
SATO, T.
S02 DSN Progress Report for March-April 1971:
Radio Science Support
K. W. Linnes, T. Sato, and D. Spitzmesser
Technical Report 32-1526, Vol. Ill, pp. 46-51, June 15, 1971
For abstract, see Linnes, K. W.
222
SAVAGE, J. E.
SOS DSN [Deep Space Network] Progress Report for Jaiiyary-
February 1971:
SymmetricaHy Decodable Codes
R. J. McEliece and J. E. Savage (Brown University)
Technical Report 32-1525, Vol. II, pp. 62-64, April 15, 1971
For abstract, see McEliece, R. J.
SCHORN, R. A. J.
504 High-Dispersion Spectroscopic Observations of Venus:
V. The Carbon Dioxide Band at 8689 A
L. D. G. Young, R. A. J. Schorn, E. S. Barker (University of
Texas), and iVl. MacFarlane (University of Texas)
Icarus: Int. J. Sol. Sys., Vol. 11, No. 3, pp. 390-407,
November 1969
For abstract, see Young, L. D. G.
505 High-Dispersion Spectroscopic Observations of Venus:
VII. The Carbon Dioxide Band at 10 488 A
L. D. G. Young, R. A. J. Sciiorn, and E. S. Barker (University of
Texas)
Icarus: Int. J. Sol. Sys., Vol. 13, No. 1, pp. 58-73, July 1970
For abstract, see Young, L. D. G.
SCHULZE, A.
806 DSN Progress Report for March-April 1971:
DSN Multiple-Mission Command System
R. R. Rakunas and A. Schuize
Technical Report 32-1526, Vol. Ill, pp. 4-6, June 15, 1971
For abstract, see Rakunas, R. R.
SCIBOR-MARCHOCKl, R. I.
S07 DSN [Deep Space Network] Progress Report for
March-April 1971:
Description of a Telemetry Procedural Language
R. I. Scibor-Marchocki
223
Technical Report 32-1526, Vol. Ill, pp. 159-167,
June 15, 1971
A procedural language and a compiler for it are being developed
as an aid in the writing of programs which will process telemetry
data received from spacecraft. This article describes the language.
Also, the philosophy that leads to the choice of the language is
briefly presented.
SHAFER, J. !.
SOS Low Acceleration Rate Ignition for Spacecraft
J. I. Shafer, L. D. Strand, and F. A. Robertson
JPL Quarterly Techn/ca/ Review, Vol. 1, No. 1, pp. 35^4,
April 1971
A g-dot ignition system for solid-prop ellant motors has been de-
signed to prevent damage to fragile sensors or structural members
on a spacecraft by producing, from a starting transient for the
spacecraft of 0.3 g, a controlled buildup in thrust, such as to give
an acceleration rate of about 0.3 g/s. The system consists of a 3-s,
regressive-burning, controUed-flow igniter and a highly inhibited
progressive-burning charge in the main motor. The igniter must
operate in a hard vacuum and sustain burning of the uninhibited
portion of the propellant below its normal L" combustion limit
through mass addition and heat transfer until the propellant sur-
face has increased sufficiently to provide a stable motor chamber
pressure. A specific internal torus-shaped igniter is described, as
well as potential methods of initiating burning in the hard
vacuum with Pyrofuze.
SHARP, R. P.,
509 The Surface of Mars: R. 1. Cratered Terrains
B. C. Murray (California Institute of Technology),
L. A. Soderblom (California Institute of Technology),
R. P. Sharp (California Institute of Technology), and
J. A. Cutts (California Institute of Technology)
J. Geophys. Res., Vol. 76, No. 2, pp. 313-330,
January 10, 1971
For abstract, see Murray, B. C.
510 The Surface of Mars: Pt. 2. Uncratered Terrains
R. P. Sharp (California Institute of Technology),
L. A. Soderblom (California Institute of Technology),
224
B. C. Murray (California Institute of Technology), and
J. A. Cutts (California Institute of Technology)
J. Geophys. Res., Vol. 76, No. 2, pp. 331-342,
January 10, 1971
The two types of uncratered terrain on Mars revealed by the
Mariner VI and VII photographs are described in this article.
The two terrains are descriptively termed chaotic and featureless.
Chaotic terrain is younger than cratered terrain and displays fea-
tures strongly suggestive of slump and collapse. The speculation
is offered that it may be an expression of geothermal develop-
ments within Mars that only recently have begun to affect the
surface. Featureless terrain, identified only within the large cir-
cular area Hellas, is devoid of any discernible topographic forms
larger than the limit of resolution, about 500 m. Mariner VII data
indicate that Hellas is a topographically low and sixucturally old
basin. Smoothness of its floor could be the product of a recent
event or of continuous processes that obliterate craters. Local pro-
cesses of high efficacy, unusual surface materials, or both are
probably involved. Through its chaotic terrain, the Martian sur-
face displays a development that does not seem to be recorded,
at least in the form of preserved recognizable evidence, on the
moon or earth.
511 The Surface of Mars: PI. 3. Light and Dark Markings
J. A. Cutts (California Institute of Technology),
L. A. Soderblom (California Institute of Technology),
R. P. Sharp (California Institute of Technology),
B. A. Smith (California Institute of Technology), and
B. C. Murray (California Institute of Technology)
J. Geophys. Res., Vol. 76, No. 2, pp. 343-356,
January 10, 1971
For abstract, see Cutts, J. A.
512 The Surface of Mars: Pt. 4. South Polar Cap
R. P. Sharp (California Institute of Technology),
B. C. Murray (California Institute of Technology),
R. B. Leighton (California Institute of Technology),
L. A. Soderblom (California Institute of Technology), and
J. A. Cutts (California Institute of Technology)
J. Geophys. Res., Vol. 76, No. 2, pp. 357-368,
January 10, 1971
As shown in the Mariner VI and VII photographs and described
in this article, the south polar cap of Mars occupies a region of
225
cratered terrain. Immediately outside the shrinking cap, craters
appear no more modified than those in areas farther north that
are not annually frost-covered. Craters showing through the frost
mantle are locally as abundant as elsewhere on Mars. Only in a
central region close to the pole are craters sparse.
Both far- and near-encounter views reveal a highly irregular pole-
cap edge. Pictures of the same sector taken six days apart are near
duplicates, suggesting that the irregularity is primarily ground-
controlled. No evidence of the classical polar collar is seen. Within
the marginal zone, frost is preserved largely in crater bottoms and
on slopes inclined away from the sun. Preferential retention in
low spots supports the earlier suggestion that the Mountains of
Mitchel may actually be depressions. An argument based on in-
coming solar radiation as the prime factor in frost wastage and
the narrow width of the marginal zone suggests that slopes of
topographic features therein are mostly gentle, on the order of a
few degrees. The frost cover of the pole-cap interior may range
widely in thickness, obscuring parts of some craters and seem-
ingly enhancing topographic visibility elsewhere, possibly through
variations in thickness and reflectivity. Unusually bright areas on
the cap surface and differences in luminance between bright rims
and the more somber floors of craters and other depressions may
be due in large part to differences in related frost textures and to
the local history of evaporation and sublimation. Irregularly
angular depressions within the pole-cap frost, termed "etch pits,"
may be the product of differential ablation or the undermining
by wind of a slabby surficial crust.
Encircling the south pole is a region of subdued relief with a
paucity of craters that displays enigmatic quasi-linear markings
believed to be ground features. Although no satisfactory expla-
nation of these markings has been formulated, it seems likely that
this region has been occupied repeatedly by perennial masses of
GO2 :ce, formed and maintained during those phases of the
Martian processional cycle that resulted in short cool summers in
the southern hemisphere. Such ice masses may play a role in pro-
ducing the unusual features of the central polar region. Physical
relationships suggest a local maximum frost thickness as great as
tens of meters. The possibility should be kept in mind that rem-
nants of perennial CO, ice of still greater thickness may exist
locally, for example, in the etch pit area.
S13 Electric Space Potential in a Cesium Thermionic Diode
K. Shimada and W. Cannon
Technical Memorandum 33-480, March 31, 1971
226
The process of cesium ionization that is influenced strongly by the
electric potential gradient is being studied to yield a minimum
plasma-loss operation. A metal-ceramic device equipped with a
movable Langmuir probe was constructed for use in investigating
cesium plasma parameters required for a minimum plasma-loss
operation of thermionic converters. To determine the space poten-
tials and the electron energies in the plasma, the probe character-
istics were examined for four difiEerent modes of cesium discharge :
(1) extinguished mode, (2) anode glow mode, (3) ball-of-fire
mode, and (4) plasma mode. This memorandmxi describes the
test device, the experimental procedures, and the results obtained.
SIEGMETH, A. J.
514 DSN Progress Report for January-February 1971:
Pioneer Mission Support
A. J. Siegmeth
Technical Report 32-1526, Vol. II, pp. 6-17, April 15, 1971
The objective of the Pioneer F and G missions is to conduct, dur-
ing the 1972-1973 Jovian opportunities, exploratory investigations
beyond the orbit of Mars of the interplanetary medium, the
nature of the asteroid belt, and the environmental and atmo-
spheric characteristics of the planet Jupiter. This article describes
the design profile of these missions. The characteristics of these
flights that interface with Deep Space Network (DSN) tracking
and data acquisition support are depicted. A delineation of the
mission description and a summary of spacecraft systems and
subsystems are given.
515 DSN [Deep Space Network] Progress Report for
IViarch-April 1971:
Pioneer Mission Support
A. J. Siegmeth
Technical Report 32-1526, Vol. Ill, pp. 7-19, June 15, 1971
This article continues the description of the Pioneer F and G mis-
sions. The tracking and data acquisition support requirements are
correlated with the mission characteristics. A description of the
spacecraft's telecommunications and antenna subsystems is given.
The CONSCAN subsystem, which has an automatic earth-homing
capability, is also delineated. The typical characteristics of the
S-band telecommunications link during Jupiter encounter are
depicted.
227
SIMON, H. S.
S16 DSN [Deep Space Network] Progress Report for
March-April 1971:
Mariner Mars 1971 Launch Phase Study Using the
SFOF Mark IfIA Central Processing System Model
H. S. Simon
Technical Report 32-1526, Vol. Ill, pp. 179-182,
June 15, 1971
Simulation models are currently being used for Space Flight Oper-
ations Facility ( SFOF ) development at the Jet Propulsion Labora-
tory. This article describes the results of three modeling runs made
during April 1971 to evaluate the performance of the SFOF Mark
IIIA Central Processing System, configxired to support the launch
phase of the Mariner Mars 1971 mission.
SMITH, B. A.
517 Mariner Mars 1969: Atmospheric Results
C. B. Leovy (University of Washington), B. A. Smith (New
Mexico State University), A. T. Young, and R. B. Leighton
(California Institute of Technology)
J. Geophys. Res., Vol. 76, No. 2, pp. 297-312,
January 10, 1971
For abstract, see Leovy, C. B.
518 The Surface of Mars: Pt. 3. Light and Dark Markings
J. A. Cutts (California Institute of Technology),
L. A. Soderblom (California Institute of Technology),
R. P. Sharp (California Institute of Technology),
B. A. Smith (California Institute of Technology), and
B. C. Murray (California Institute of Technology)
J. Geophys. Res., Vol. 76, No. 2, pp. 343-356,
January 10, 1971
For abstract, see Cutts, J, A.
SNiFFIN, R.
S19 DSN Progress Report for March-April 1971:
Implementation of an S-Band Microwave Link
for Spacecraft Compatibility Testing
R. Sniffin
228
Technical Report 32-1526, Vol. Ill, pp. 203-210,
June 15, 1971
The Deep Space Network (DSN) requires all spacecraft that are
to be tracked by its stations receive a compatibility test prior to
launch. Two facilities are maintained for this purpose: one at Cape
Kennedy ( DSS 71 ) for pre-launch checkout of the spacecraft, and
another at JPL in Pasadena (CTA 21) for engineering clieckout
of spacecraft and spacecraft subsystems before shipment to the
launch facility. As a cost- and time-effective approach to compati-
bility testing of the Pioneer F and G spacecraft being constructed
by TRW Inc., a microwave link between JPL and TRW has been
installed. The performance of this link has been evaluated experi-
mentally and test results are given.
SODERBLOM, L A.
520 The Surface of Mars: Pt. 1. Cratered Terrains
B. C. Murray (California Institute of Technology),
L. A. Soderblona (California Institute of Technology),
R. P. Sharp (California institute of Technology), and
J. A. Cutts (California Institute of Technology)
J. Geophys. Res., Vol. 76, No. 2, pp. 313-330,
January 10, 1971
For abstract, see Murray, B. C.
521 The Surface of Mars: Pt. 2. Uncratered Terrains
R. P. Sharp (California Institute of Technology),
L. A. Soderblom (California Institute of Technology),
B. C. Murray (California Institute of Technology), and
J. A. Cutts (California Institute of Technology)
J. Geophys. Res., Vol. 76, No. 2, pp. 331-342,
January 10, 1971
For abstract, see Sharp, R. P.
522 The Surface of Mars: Pt. 3. Light and Dark Markings
J. A. Cutts (California Institute of Technology),
L. A. Soderblom (California Institute of Technology),
R. P. Sharp (California Institute of Technology),
B. A. Smith (California Institute of Technology), and
B. C. Murray (California Institute of Technology)
J. Geopfiys. Res., Vol. 76, No. 2, pp. 343-356,
January 10, 1971
For abstract, see Cutts, J. A.
229
S23 Tlie Surface of Mars: Pt. 4. South Polar Cap
R. P. Sharp (California Institute of Technology),
B. C. Murray (California Institute of Technology),
R. B. Leighton (California Institute of Technology),
L. A. Soderblom (California Institute of Technology), and
J. A. Cutts (California Institute of Technology)
J. Geophys. Res., Vol. 76, No. 2, pp. 357-368,
January 10, 1971
For abstract, see Sharp, R. P.
SPIER, G. W.
S24 Design and Implementation of Models for the Double
Precision Trajectory Program (DPTRAJ)
G. W. Spier
Technical Memorandum 33-451, April 15, 1971
A common requirement for all lunar and planetary missions is the
extremely accurate determination of the trajectory of a spacecraft.
The Double Precision Trajectory Program (DPTRAJ) developed
by JPL proved to be a very accurate and dependable tool for the
computation of interplanetary trajectories during the Mariner
Mars 1969 missions. This memorandum describes the mathe-
matical models that are currently used in the DPTRAJ, with
emphasis on the development of the equations.
SPITZMESSER, D.
525 DSN Progress Report for March-April 1971:
Radio Science Support
K. W. Linnes, T. Sato, and D. Spitzmesser
Technical Report 32-1526, Vol. ill, pp. 46-51, June 15, 1971
For abstract, see Linnes, K. W.
STOLLER, F.
526 Bolted Joints Under Sustained Loading
V. Lobb and F. Stoller
J. Struct. D/V., Pfoc. ASCE, Vol. 97, No. ST3, pp. 905-933,
March 1971
For abstract, see Lobb, V.
230
STRAND, L D.
527 Low Acceleration Rate Ignition for Spacecraft
J. I. Shafer, L. D. Strand, and F. A. Robertson
JPL Quarterly Technical Review, Vol. 1, No. 1, pp. 35--44,
April 1971
For abstract, see Shafer, J. I.
STROMBERG, W. D.
528 Digital Processing of the Manner 6 and 7 Pictures
T. C. Rindfleisch, J. A. Dunne, H. J. Frieden, W. D. Stromberg,
and R. M. Ruiz
J. Geophys. Res., Vol. 76, No. 2, pp. 394-417,
January 10, 1971
For abstract, see Rindfleisch, T. C.
S29 Maximum Discriminability Versions of the Near-Encounter
Mariner Pictures
J. A. Dunne, W. D. Stromberg, R. M. Ruiz, S. A. Collins,
and T. E. Thorpe
J. Geophys. Res., Vol. 76, No. 2, pp. 438-472,
January 10, 1971
For abstract, see Dunne, J. A.
SWARD, A.
S30 DSN [Deep Space Network] Progress Report for
January-February 1971:
New Developments in the Hydrogen Maser Frequency Standard
A. Sward
Technical Report 32-1526, Vol. II, pp. 72-74, April 15, 1971
Measurements have been made on the JPL hydrogen masers to
determine the average fractional frequency departure versus aver-
aging time. In addition, the receiver section has been modified
v^^ith a newly developed frequency synthesizer that will not only
improve the performance and reliability of the receiver but also
decrease its size and complexity.
231
TAYLOR, T. M.
TO! Tracking and Data System Support for the Mariner Mars 1969
Mission: Planning Phase Through Midcourse Maneuver
N. A. Renzetti, K. W. Linnes, D. L. Gordon, and T. M. Taylor
Technical Memorandum 33-474, Vol. I, May 15, 1971
For abstract, see Renzetti, N. A.
THORPE, T. E,
T02 Maximum Discriminability Versions of the Near-Encounter
Mariner Pictures
J. A. Dunne, W. D. Stromberg, R. M. Ruiz, 8. A. Collins,
and T. E. Thorpe
J. Geophys. Res., Vol. 76, No. 2, pp. 438-472,
January 10, 1971
For abstract, see Dunne, J. A.
TIMOR, U.
T03 DSN [Deep Space Network] Progress Report for
January-February 1971:
Sequential Ranging With the Viterbi Algorithm
U. Timor
Technical Report 32-1526, Vol. 11, pp. 75-79, April 15, 1971
The performance of the sequential ranging system can be improved
by using a maximum-likelihood receiver; however, the complexity
grows exponentially with the number of components N needed to
determine the range unambiguously. A new truncated maximum-
likelihood receiver, based on the Viterbi decoder for convolutional
codes, is presented and is shown to achieve a maximum-likelihood
performance while having a fixed complexity independent of N.
The improvement in signal-to-noise ratio, compared to the present
receiver, is 1.5 db for an error probability of less than 10"^.
104 Interplex Modulation
S. Butrrian and U. Timor
JPL Quarterly Technical Review, Vol. 1, No. 1, pp. 97-105,
April 1971
For abstract, see Butman, S.
232
TRAJMAR, S.
T05 Electron Impact Excitation of N2
R. T. Brinkmann and S. Trajmar
Ann. Geophys., Vol. 26, No. 1, pp. 201-207,
January-March 1970
For abstract, see Brinkmann, R. T.
TURNER, J. A.
T06 DSN Progress Report for March-April 1971:
Operational Capabilities of the SFOF Mark IIIA
User Terminal and Display Subsystem
J. A. Turner
Technical Report 32-1526, Vol. Ill, pp. 228-238,
June 15, 1971
The Space Flight Operations Facility (SFOF) Mark IIIA Central
Processing System has been developed to meet requirements for
independent and simultaneous operation of multiple missions
flown by an array of increasingly complex and sophisticated space-
craft. The Deep Space Network (DSN) Operations and Mission
Support Areas must all be supported by the same computer sys-
tem and therefore have been equipped with identical user input/
output devices. The user input/output devices and their capabil-
ities are described with the suggestion that operating techniques
be developed and adapted to the improved and more interactive
input/output capabilities of the new User Terminal and Display
Subsystem.
TUSTIN, D. G.
T07 DSN Progress Report for January-February 1971:
DSN Discrepancy Reporting Subsystem
D. G. Tustin
Technical Report 32-1526, Vol. II, p. 140, April 15, 1971
The Deep Space Network (DSN) discrepancy reporting subsystem
for collecting and cataloging all documented reports of operational
discrepancies facilitates rapid retrieval of required information
using varied selection criteria. The discrepancy reporting sub-
system and the results of the first year's discrepancy reporting
operation using a computerized data managen:ient system are
briefly described. The general problems encountered and the steps
being taken to solve them are discussed.
233
URECH, J. M.
UOl DSN Progress Report for January-February 1971:
Processed Data Combination for Telemetry Improvement—
DSS 62
J. M. Uirech
Technical Report 32-1525, Vol. II, pp. 169-176, April 15, 1971
Telemeiixy improvement proposals for the Deep Space Network
(DSN) 26-m antenna network are being considered. Of the four
possible methods of improving telemetry bit error rate perfor-
mance by combining data with common time tags from two sta-
tions, this article discusses the method of a posteriori combination
of processed telemetry data. The theory is presented and the results
of a scheduled test with a Pioneer spacecraft are shown to be in
good agreement.
Although the method is ideally applicable to two deep space
stations (DSSs) with the same configuration [two ground opera-
tional equipment (GOE) or two multiple-mission telemetry (MMT)
stations], the computer program was developed at DSS 62
(Cebreros DSS) for apphcation to DSS 61 (Robledo DSS) with a
GOE configuration and DSS 62 with an MMT configuration. The
computer program is described in an appendix.
VOLKOFF, J. J.
¥§1 DSN [Deep Space Network] Progress Report for
Janyary-February 1971:
Photon Energies of a Cathode-Ray Tube System
J. J. Volkoff
Technical Report 32-1526, Vol. II, pp. 92-99, April 15, 1971
Light emitted from a cathode-ray tube (CRT) is comprised of
reflected environmental light incident upon the CRT system and
light generated at the phosphor screen and transmitted through
the CRT system. The total photon energy that leaves the system
and those energies that are dissipated in the various elements of
the CRT system are derived. An expression for the contrast ratio
of the CRT system is also presented and discussed.
¥0N ROOS, 0. H.
¥02 DSN Progress Report for January-February 1971:
Second Order Charged Particle Effects on Electromagnetic
Wa¥es in the Interplanetary Medium
0. H. von Roos
234
Technical Report 32-1526, Vol. II, pp. 42-48, April 15, 1971
Possible influences on the measurements of the total electron
content due to magnetic fields, spatial inhomogeneities, and pulse
shape distortions are investigated. The higher-order effects of the
interplanetary plasma on radio signals as utilized in the Deep
Space Network (DSN) are shown to be negligible as far as a
determination of the electron content is concerned. It is seen
that a lateral change in electron concentration engenders very
small angular deviations of the ray path and leads to a negligible
change in the apparent range.
V03 DSN [Deep Space Network] Progress Report for
March-April 1971:
Analysis of the DRVID and Dual Frequency Tracking Methods
in the Presence of a Time-Varying Interplanetary IPIasma
0. H. von Roos
Technical Report 32-1526, Vol. Hi, pp. 71-76, June 15, 1971
An analysis is made of two different methods for determining the
total electron content of the plasma existing between a spacecraft
and the earth. It is shown that the two methods complement each
other. The dual frequency method is capable of measuring the
structure of a plasma inhomogeneity, whereas the differenced
range versus integrated doppler ( DRVID ) method is capable of
locating this inhomogeneity within the ray patli of the electro-
magnetic tracking signal.
WAHLQUIST, H. D.
WOl Applications of FORMAC in the Mathematics of
General Relativity
H. D. Wahlquist
JPL Quarterly Techn/ca/ Review, Vol. 1, No. 1, pp. 13-16,
April 1971
The use of FORMAC (formula manipulation by computer) to
perform symbolic analysis on the computer in the field of general
relativity is described. FORMAC will accept symbolic analytical
expressions involving complex algebraic functions, elementary
transcendental functions, user-defined functions, and unspecified
functions of any number of dependent variables. In particular,
FORMAC programs have now been written to implement the non-
commutative calculus of exterior differential forms. Applications
of this new capability to Hamiltonian cosmology and the theory of
partial differential equations are discussed.
235
WALLACE, K. B.
W§2 DSN [Deep Space Network] Progress Report for
March-April 1971:
Noise Diode Evaluation
K. B. Wallace
Technical Report 32-1526, Vol. Ill, pp. 121-125,
June 15, 1971
Noise diodes are installed in all R&D microwave receiver sys-
tems to check broadband receiver performance required for
radiometric applications, such as radio astronomy and atmo-
spheric studies. An application to which noise sources are par-
ticularly suited is the noise-adding radiometer; another applica-
tion being studied is automated system performance evaluation.
In this article, noise diodes similar to those in use at Deep Space
Stations 13 and 14 are evaluated for variations in noise output
due to temperature.
WEBER, R.
W03 DSN Progress Report for Marcli-April 1971:
MSFN/DSN Integration Program for the DSS 11 26-m
Antenna Prototype Station
R. Weber
Technical Report 32-1526, Vol. Ill, pp. 197-202,
June 15, 1971
A plan vfas proposed in mid-1971 wherein unique Deep Space
Network (DSN) equipment would be installed in the 26-m
antenna Manned Space Flight Network (MSFN) operations con-
trol roona and integrated to function with pre-existing MSFN
equipment. This effort was initiated at the Pioneer Deep Space
Station (DSS 11) site in November 1970 and shortly thereafter at
the two overseas sites. This plan allows the 26-m antenna DSN
tracking capability to exist at these sites while the 64-m antenna
is in the process of being built and integrated into the original
26-m antenna DSN control room. The details of the integration
efforts at the DSS 11 prototype station are outlined, and signifi-
cant accomplishments and milestones are indicated. The equip-
ment layout in the operations control room is illustrated and the
unique operational and electrical interfaces between the DSN
equipment and the MSFN equipment are described.
236
WEIDNER, J. H.
W04 DSN Progress Report for March-April 1971:
Software for the DSN Video Subsystem
J. H.Weidner
Technical Report 32-1526, Vol. Ill, pp. 239-244,
June 15, 1971
The Deep Space Network (DSN) video subsystem provides the
flight projects at JPL with a real-time and near real-time tonal
image (picture) processing and display capability. The software
of the subsystem controls all components and processes the
pictxire data which it receives from the DSN Telemetry System.
The video software is designed to give the flight projects the
capability to automatically process, display, and record the
picture data as they are received from the spacecraft. Its design
also includes an interactive capability for selective picture
processing and display.
WEINER, E. 0.
W05 Computation of Structural Modes of a Rollout Array Spacecraft
for Attitude Control Study
E. 0. Weiner
Technical iVIemorandum 33-476, May 1, 1971
A study is presented of the structural modes required to determine
the interaction between an attitude control system and a flexible
structure. The flexible structure considered has a low stiffness that
leads to natural frequencies in the range of the frequency response
of the attitude control system, producing a coupling between the
response of the structure and the attitude control system.
WEIR, C. E.
W06 DSN [Deep Space Network] Progress Report for
IVIarch-Apri! 1971:
Rotating Antenna Tests at DSS 12
C. E. Weir
Technical Report 32-1526, Vol. Ill, pp. 215-218,
June 15, 1971
The Pioneer F spacecraft will utilize a conical scan system to
allow automatic pointing of its antenna at the earth. The space-
craft will rotate continuously about the roll axis during the mis-
sion, and will consequently present some characteristics to a
237
ground station not seen on previous missions. Tests were con-
ducted using a rotating antenna on the coUimation tower at
DSS 12 (Echo Deep Space Station) to simulate the rotating
Pioneer F spacecraft. Specific measurements were taken to deter-
mine the degradation in telemetry bit error rate and doppler
quality as a result of the rotation and misalignment of the
rotating antenna relative to the receiving antenna.
WELLS, R. A.
W07 DSN [Deep Space Network] Progress Report for
Jaiiuar)f-February 1971:
Diagnostics for the SFOF Mark IllA Central Processing System:
Pre-Mission CPS/Facllity Checkout Procedures
R. A. Wells
Technical Report 32-1526, Vol. II, pp. 125-128, April 15, 1971
Prior to critical periods of data processing during a mission, com-
prehensive diagnostic tests of the Space Flight Operations Facility
(SFOF) central processing system (GPS) are conducted to detect
and correct equipment deficiencies before they can affect the
continuity of the data processing. This article describes the test
methods employed and their relationships to the current dual
IBM 360/75 computer configuration. By preparing a test "script"
in advance, the hardware checkout process is formalized and the
results documented.
WEN, L C.
W08 Measyred Performance of Silicon Solar Cell Assemblies
Designed for Use at High Solar Intensities
R. G. Ross, Jr., R. K. Yasui, W. Jaworski, L C. Wen,
and E. L. Cleland
Technical Memorandum 33-473, March 15, 1971
For abstract, see Ross, R. G., Jr.
WILLIAMS, J. G.
W09 Resonances in the Neptune-Pluto System
J. G. Williams and G. S. Benson (University of
California, Los Angeles)
Astron. J., Vol. 76, No. 2, pp. 167-177, March 1971
Pluto's orbit has been integrated for 4.5 million years. The previ-
ously discovered libration of 3A — 2Xy — To, where A and Ay are
238
the mean longitudes of Pluto and Neptune and a is Pluto's longi-
tude of perihelion, is confirmed and has an average period of
19 951 yr. It was also found that the argument of perihelion «
librates about 90 deg with an amplitude of 24 deg and a period of
3 955 000 ± 20 000 yr. There is an indication that both the dif-
ference between the nodes and the difference between the
longitudes of perihelia of Neptune and Pluto may be locked on
to the (1) libration. All of the above eflFects are found to improve
the stability of the Neptune-Pluto system by increasing the
minimum distance of approach between the two bodies.
YASUI, R. K.
YOl Structural Analysis of Silicon Solar Arrays
L. W. Butterworth and R. K. Yasui
Technical Report 32-1528, May 15, 1971
For abstract, see Butterworth, L. W.
Y02 Measured Performance of Silicon Solar Cell Assemblies
Designed for Use at High Solar Intensities
R. G. Ross, Jr., R. K. Yasui, W. Jaworski, L. C. Wen,
and E. L Cleland
Technical Memorandum 33-473, March 15, 1971
For abstract, see Ross, R. G., Jr.
YEH, C.
Y03 Arbitrarily Shaped Dual-Reflector Antennas
C. Yeh
Technical Report 32-1503, May 1, 1971
An analysis based on geometrical optics for a dual-reflector an-
tenna system with two arbitrarily shaped reflectors is carried out.
Formulas for the phase and amplitude distribution in the aperture
of the second reflector are obtained when the source function and
the reflector surfaces are given. A design technique based on the
derived formulas is also discussed.
YOUNG, A. T.
Y04 Mariner Mars 1969: Atmospheric Results
C. B. Leovy (University of Washington), B. A. Smith (New
Mexico State University), A. T. Young, and R. B. Leighton
(California Institute of Technology)
239
J. Geophys. Res., Vol. 76, No. 2, pp. 297-312,
January 10, 1971
For abstract, see Leovy, C. B.
Y05 Photometric Properties of tiie Mariner Cameras and of
Selected Regions on Mars
A. T. Young and S. A. Collins
J. Geophys. Res., Vol. 76, No. 2, pp. 432-437,
January 10, 1971
The reciprocity principle was found to be a very effective test of
linearity in the Mariner VI and VII television data. For the test-
ing, areas on Mars were selected that were reasonably uniform,
so as to avoid resolution-dependent effects. The areas were also
selected so as to avoid any obvious diurnal "cloud" phenomena.
As described in this article, in spite of serious problems with the
photometric data, significant variations were found in limb-
darkening from place to place on Mars. These variations enable
a new parameter of the Martian surface (most probably the grain
size or degree of compaction) to be studied.
YOUNG, L. D. G.
Y06 High-Dispersion Spectroscopic Observations of Venus:
V. The Carbon Dioxide Band at 8689 A
L. D. G. Young, R. A. J. Schorn, E. S. Barker (University of
Texas), and M. MacFarlane (University of Texas)
Icarus: Int. J. Sol. Sys., Vol. 11, No. 3, pp. 390^07,
November 1969
The average rotational temperature of the Cytherean atmosphere
above the "cloudtops" was found to be 238 ± 1 K (standard
deviation) based on 23 plates of the 8689-A CO2 band. If the
temperatures found from the 8689-, 7820-, and 7883-A bands are
averaged for each plate on which these bands appear, an average
rotational temperature of 242 zfc 2 K (standard deviation) is ob-
tained. This latter temperature is based on 31 plates taken of
Venus between March and December 1967. The variation of the
equivalent width of the 8689-A band with Venus phase is seen
to agree generally with the observations of Kuiper; the equivalent
width decreases with increasing phase angles.
Y07 High-Dispersion Spectroscopic Observations of Venus:
VII. The Carbon Dioxide Band at 10 488 A
L D. G. Young, R. A. J. Schorn, E. S. Barker (University
of Texas), and M. MacFarlane (University of Texas)
Icarus: lr)t. J. Sol. Sys., Vol. 13, No. 1, pp. 58-73, July 1970
240
Observations of the 10,488-A band of carbon dioxide in the spec-
trum of Venus were made from January 1965 through December
1967. The spectra were obtained at the coude focus of the Struve
reflector at dispersions of 2.8, 3.8, and 5.4 A/mm. The 31 best
plates were used to derive rotational temperatures by two
methods. In the first method, linear least-squares fits to a square-
root absorption law were made, and temperatures ranging from
193 to 284 K were derived; the average temperature was 244 K.
The second method also required a linear least-squares fit, this
time to the curve of growth. This fit gave slopes from 0.38 to 0.58,
corresponding to rotational temperatures of 202 to 250 K, with an
average temperature of 236 K. The rotational temperatures de-
rived by both methods showed no significant variation with the
phase angle i of Venus for 26 ^ i, deg ^ 164. Finally, averaging
the measurements obtained by three individuals and using the
curve-of-growth method of data reduction gives a value for rota-
tional temperature of 237 ± 3 K (formal standard deviation).
A search was made for spatial and temporal variations in the ap-
parent amount of carbon dioxide in the absorption path. The
amount appeared to vary significantly with the phase of Venus
and also with the time of observation.
ZANDELL, C.
ZOl DSN [Deep Space Network] Progress Report for
March-April 1971:
Diagnostics for the SFOF Mark IIIA Central Processing
System: Real-Time Background Routines
C. Zandell
Technical Report 32-1526, Vol. Ill, pp. 168-170,
June 15, 1971
The on-line diagnostics for the Space Flight Operations Facility
(SFOF) Central Processing System (GPS) have been modified
to provide real-time diagnosis of equipment performance. Real-
time diagnostics can be run while mission flight support con-
tinues. This is possible since any diagnostic can now run as an
independent task under the mission real-time job step. The
real-time capability allows certification of CPS hardware ele-
ments immediately preceding their commitment to mission flight
support.
ZMUIDZINAS, J. S.
Z02 Self-Consistent Green's-Function Approach to the
Electron-Gas Problem
J. S. Zmuidzinas
241
Phys. Rev., Pt B: Solid State, Vol. 2, No. 11, pp. 4445-4460,
December 1, 1970
The electron-gas problem is investigated by means of a self-
consistent Green's-function formalism with the aim of developing
practical approximation schemes for metallic densities. The vs^ork
is based on the Dyson equation for the single-particle propagator
G[U] as a functional of an external potential U. The self-energy
functional 2[U], appearing in the Dyson equation, is evaluated
by perturbation theory in terms of the exact G[U], thereby lead-
ing to a self-consistent problem. A hierarchy of approximations is
generated by summing successively larger sets of graphs for X[U].
The Dyson equation is expanded in a functional Taylor series in
U and yields a nonlinear integral equation for the U = propa-
gator, as well as linear integral equations for the C7 = higher-
order Green's functions, with kernels dependent on S2/8U. In
applications of the theory, the emphasis is on calculating the
longitudinal dielectric function e in terms of the contracted four-
point Green's function. The linear integral equation for the latter is
solved after making a low-momentum dominance approximation
to the kernel. The result is a general, but approximate, closed-form
expression for e which can be used for different choices of S. The
following five approximations for e, based on different approxima-
tions for 2, are presented: Hartree-Fock, random-phase, gen-
eralized random-phase, second-stage random-phase, and low-
density-high-density approximations. The last approximation is
designed to work well at the two extremes of the density spectrum
and, hopefully, also at metallic densities. The long- wavelength
plasmon dispersion relations obtained from two different versions
of the generalized random-phase approximation for e agree closely
with the results reported by Kanazawa and Singwi.
ZOHAR, S.
Z03 DSN [Deep Space Network] Progress Report for
March-April 1971:
Matched Filters for Binary Signals: A Correction
and Elaboration
S. Zohar
Technical Report 32-1526, Vol. Ill, pp. 116-120,
June 15, 1971
This article is a correction and elaboration of "DSN Progress
Report for November-December 1970: Matched Filters for
Binary- Signals," Technical Report 32-1526, Vol. I, pp. 52-62,
February 15, 1971. That article described the design of matched
filters for the optimal high-speed detection of binary signals and
investigated their performance as a function of their complexity.
242
Subject Index
Subject Categories
Antennas and Transmission
Lines
Apollo Project
Atmospheric Entry
Biology
Chemistry
Computer Applications
and Equipment
Computer Programs
Control and Guidance
Earth Atmosphere
Earth Surface
Electricity and Magnetism
Electronic Components
and Circuits
Facility Engineering
Fluid Mechanics
Helios Project
Information Theory
Launch Operations
Lunar Exploration, Advanced
Lunar Surface
Management Systems
Manner Mars 1969 Project
Mariner Mars 1971 Project
Mariner Venus 67 Project
Mariner Venus-Mercury
1973 Project
Masers and Lasers
Materials, Metallic
Materials, Nonmetallic
Mathematical Sciences
Mechanics
Mechanisms
Optics
Orbits and Trajectories
Packaging and Cabling
Particle Physics
Photography
Pioneer Project
Planetary Atmospheres
Planetary Exploration,
Advanced
Planetary Interiors
Planetary Motion
Planetary Spacecraft,
Advanced
Planetary Surfaces
Plasma Physics
Power Sources
Propulsion, Electric
Propulsion, Liquid
Propulsion, Solid
Pyrotechnics
Quality Assurance
and Reliability
Radar
Radio Astronomy
Relativit','
243
Safety Engineering
Scientific Instruments
Soil Sciences
Soiid-State Physics
Spectrometry
Standards, Reference
Structural Engineering
Surveyor Project
Telemetry and Command
Temperature Control
Test Facilities and
Equipment
Thermodynamics
Tracking
Viking Project
Wave Propagation
Subjects
SuiJJect Entry
Antennas and Transmission Lines
predicted and measured power density description
of a large ground microwave system B07
Helios spacecraft antennas G05
Venus Deep Space Station (DSS 13)
26-m antenna upgrade JOl
computer program for antenna member size changes L09
tests of bolted antenna structural joints under
sustained loading L15
antenna support structure aperture blockage loss L17
evaluation of field measurements of reflector distortions M05
Deep Space Instrumentation Facility
overseas 64-m antenna project M17
26-m antenna HA-dec counter torque modifications M20
new designs for large spacecraft antennas O02
microwave transmission through perforated flat plates O05
analysis of boresight error calibration procedure for
compact rotary vane attenuators O06
lieat exchanger for 64-m antenna hydrostatic bearing P04
system operating noise temperature calibrations
of feed cones R03
antenna facilities used in support of Pioneer Project R07
applications of two-dimensional integral-equation theory
to reflector-antenna analysis R20
Pioneer spacecraft antenna S15
rotating antenna tests in simulation of Pioneer F spacecraft W06
arbitrarily shaped dual -reflector antennas Y03
Apollo Project
potassium-uranium systematics of Apollo 11 and Apollo 12
samples : implications for lunar material history FOl
Deep Space Network support F05
H07
lunar bistatic radar experiment F05
244
Subject Entry
Apollo Project (contd)
Apollo 14 mission description H07
blowing of lunar soil by Apollo 12 onto Surveyor III J03
study of mechanical interaction of a driven roller on
soil slopes preliminary to construction of
Apollo lunar roving vehicle K05
Manned Space Fhght Network/Deep Space Network
integration for project support . W03
Atmospheric Entry
new, higher performance electric-arc-driven shock tube
for study of atmospheric entry problems M19
Biology
growth of bacteria in soils from Antarctic dry valleys COl
survival of Antarctic desert soil bacteria exposed to
various temperatures and 3 yr of continuous
medium-high vacuum C02
microbial and ecological studies of recent cinder cones
at Deception Island, Antarctica C03
photocatalytic production of organic compounds from
CO and H2O in simulated Martian atmosphere H16
relationship of cyanate ion to uremic syndrome 101
Chemistry
pumping mechanism of COo laser and formation rate
of CO, from CO and O C07
evaluation of dependence of ^/(H — H)
on bond angle in alkenes and cycloalkenes C12
measurement of organic carbon in arid soils
using hydrogen-flame ionization detector G02
conformational preferences of N-trimethylsilyl and
O-trimethylsilyl groups H04
photocatalytic production of organic compounds from
CO and H2O in simulated Martian atmosphere H16
relative rates and their dependence on kinetic energy
for ion-molecule reactions in ammonia H18
relationship of cyanate ion to uremic syndrome 101
oil-absorbing polymers M08
shock-tube thermochemistry tables for
high-temperature gases M18
estimation of polymer molecular weight from refractive index R12
Computer Applications and Equipment
Deep Space Instrumentation Facility near-Earth
telemetry automatic switching unit B19
digital processing of Mariner Mars 1969 photographs DIO
R14
245
Subject Entry
Computer Applications and Equipment (contd)
multiclass sequential hypothesis test with appHcations
ill pattern lecognition to aid in design of
reading machines Hll
computer-controlled operating and data handling
system for quadrupole mass spectrometer H15
Space Flight Operations Facility Mark IIIA user
terminal and display subsystem K02
T06
optimal frame synchronization K03
Space Flight Operations Facility digital
television computer subassembly LOS
Deep Space Network Mark IIIA Simulation Center
interactive alphanumeric television system L04
effect of till additive on indium thin-film superconducting
transmission lines for possible application to a
large-scale superconducting computer Mil
digital step attenuator for ranging demodulator OOl
computer for strapdown, electrically suspended
gyro, aerospace navigation system POl
Mariner Mars 1971 launch-phase study using
Space Flight Operations Facility Mark IIIA
central processing system model S16
processed data combination for telemetry improvement UOl
use of FORMAC (formula manipulation by computer)
in mathematics of general relativity and in
noncommutative calculus of exterior differential forms WOl
Space Flight Operations Facility central processing
system pre-mission checkout procedures W07
diagnostics for Space Flight Operations Facility
Mark IIIA central processing system ZOl
Computer Programs
Deep Space Network Monitor System software status A02
program using Monte Carlo method to calculate
electron-impact excitation of N, B16
program for analysis of traveling-wave tubes D07
subroutine for multi-rigid-body dynamics simulation F06
low-rate spectral electron irradiation program JOS
program for soil-wheel interaction performance (S WIP) KG5
structural design and stress analysis program (COMTANK)
for advanced composite filament-wound axisymmetric
pressure vessels K06
system of subroutines for solving initial value problem in
ordinary differential equations K08
program for antenna member size changes L09
246
Subject Entry
Computer Programs (contd)
software for Deep Space Network Tracking System
analytic calibration activities for support of
Mariner Mars 1971 Project M03
Deep Space Network traceability and reporting program M23
programs for radiometric data accountability, validation,
and selection in real time M24
mathematical formulation of double-precision orbit
determination program (DPODP) M29
programs used in Tracking and Data System support
for Pioneer Project R07
telemetry procedural language 807
command generation program (COMGEN) applied to
Mariner Mars 1971 launch-phase study using Space Flight
Operations Facility Mark IIIA central processing
system model S16
design and implementation of models for double-precision
trajectory program (DPTRAJ) 824
program for processed data combination for
telemetry improvement UOl
programs and subroutines for use of FORMAC (formula
manipulation by computer) in mathematics of general
relativity and in noncommutative calculus of
exterior differential forms WOl
software for Deep Space Network video subsystem W04
programming for computation of structural modes of a
rollout array spacecraft for attitude-control study W05
diagnostics for Space Flight Operations Facility
Mark IIIA central processing system ZOl
Control and Guidance
multi-rigid-body attitude dynamics simulation F06
passive damping of forced precession of a
two-body satellite LU
development of strapdown, electrically suspended
gyro, aerospace navigation system POl
Pioneer F and G spacecraft control and guidance S14
computation of structural modes of a rollout-array
spacecraft for attitude-control study W05
Earth Atmosphere
electron-impact excitation of No relative to
aurora and airglow B16
sensitivity of tropospheric range and doppler
effects to shape of refractivity profile C06
effect of absorption on scattering by atmosphere Fll
247
Subject Entry
Earth Surface
growth of bacteria in soils from Antarctic dry valleys COl
survival of Antarctic desert soil bacteria exposed to
various temperatures and 3 yr of continuous
medium-liigli vacuum C02
microbial and ecological studies of recent cinder cones at
Deception Island, Antarctica COS
Electricity and Magnetism
calculation of space-charge forces in analysis of
traveIing-^vave tubes D07
second-order charged-particle effects on electromagnetic
waves in the interplanetary medium V02
Electronic Components and Circuits
magnetic tape recorder for long operating life in space BOS
Deep Space Instrumentation Facility near-Earth telemetry
automatic switching unit B19
calculation of space-charge forces in analysis of
traveling-wave tubes DOT
new high-voltage crowbar F02
hydrogen maser cavity tuning servo FOS
S-band demodulator F07
wideband digital pseudo-gaussian noise generator H19
acceptance testing of Deep Space Instrumentation
Facility klystrons JOl
Mars Deep Space Station (DSS 14) 400-kW harmonic filter JOl
switched-carrier experiments K07
electrical characteristics of AIN insulating films for
capacitors LIO
hardware version of optimal convolutional decoder H8
improved freciuency dividers for hydrogen maser
frequency standard L19
effect of tin additive on indium thin-film superconducting
trarismission lines Mil
stability comparison of three frequency synthesizers M22
digital step attenuator for ranging demodulator OOl
Boolean difference calculus used for detecting faults in
switching circuit gates R02
noise diode evaluation W02
Facility Engineering
Ground Communications Facility television assembly
design for systems development laboratory B12
Deep Space Network coherent reference generator
and distribution subsystem C14
248
Subject Entry
Facility Engineering (contd)
modifications to deep space stations for
support of Apollo Project • F05
Ground Communications Facility microwave
terminal reconfiguration H03
upgrading of deep space stations JOl
Deep Space Network Operations Control System
high-speed data transfer network M02
Deep Space Instrumentation Facility overseas
64-m antenna construction M17
26-m antenna HA-dec counter torque modifications M20
Space Flight Operations Facility cable control plan P02
heat exchanger for 64-m antenna hydrostatic bearing P04
S-band microwave link implementation . S19
Manned Space FHght Network/Deep Space Network
integration for support of Apollo Project W03
Fluid Mechanics
static pressure measurements near an oblique shock wave BOl
flow coefficients for supersonic nozzles with small radius of
curvature throats B02
Helios Project
Deep Space Network support G05
G06
Helios Project organization G05
spacecraft design G0.5
Information Theory
interplex modulation B20
rate distortion over band-limited feedback channels ............. B21
wideband digital pseudo-gaussian noise generator H19
optimal frame synchronization algorithms K()3
hardware version of optimal convolutional decoder L18
limits of minimum distance decoding M13
symmetrically decodable codes M14
synchronization of noisy video M15
first-order theory for investigating information
content of a few days' radio tracking data OOS
Boolean difference calculus used for detecting
faults in switching circuit gates ■ . ■ B.02
sequential ranging using Viterbi algorithm T03
processed data combination for telemetry improvemeDt UOl
matched filters for binary signals Z03
Launch Operations
Mariner Mars 1971 launch-phase study using
Space Flight Operations Facility Mark IIIA
central processing system model S16
249
Subject Entry
Lunar Exploration, Advanced
comparison of lunar traverse missions studied by
JPL and Lunokhod 1 lunar rover mission B15
study of mechanical interaction of a driven roller
on soil slopes preliminary to construction
of a lunar roving vehicle K05
Limar Surface
potassium-uranium systematics of Apollo 11 and
Apollo 12 samples: implications for lunar
material history FOl
Apollo bistatic radar experiment F05
blowing of lunar soil by Apollo 12 onto Surveyor 111 JOS
Management Systems
Deep Space Network Monitor System analysis group A02
Helios Project organization G05
Deep Space Network configuration for support
of Mariner Mars 1971 Project LOl
Deep Space Network Operations Control System M02
Deep Space Network organization R05
R06
Deep Space Network discrepancy reporting subsystem T07
Mariner Mars 1969 Project
photographic results of missions C22
C24
D04
DIO
LOS
LOS
M34
SIO
S12
Y05
calibration of television cameras D02
digital processing of mission photographs DIO
R14
Deep Space Network support Rll
photometric properties of television cameras
and of selected regions on Mars Y05
Mariner Mars 1971 Project
teletype configuration in support of
ground communications B13
Deep Space Network support LOl
Deep Space Network Tracking System analytic
calibration activities for project support M03
250
Subject Entry
Mariner Mars 1971 Project (contd)
Ground Communications Facility system
tests for project support N06
launch-phase study using Space Flight
Operations Facility Mark IIIA central
processing system model S16
Mariner Venus 67 Project
neutral atmosphere of Venus studied with
radio occultation by Mariner V F04
Mariner Venus-Mercury 1973 Project
mission description B14
spacecraft description B14
synchronization of noisy video M15
Masers and Lasers
pumping mechanism of CO, laser and
formation rate of CO, from CO and O C07
hydrogen maser frequency standard F03
L19
S30
Materials, Metallic
metal material properties as used in COMTANK,
a structural design computer program for
filament-wound pressure vessels K06
Materials, Nonmetallic
fatigue of Teflon bladder bag materials C15
solid propellants with reduced burning rates H17
properties of boron/epoxy material as used in
COMTANK, a structural design computer program
for filament-wound pressure vessels K06
oil-absorbing polymers M08
Mathematical Sciences
graph theory and its applications D06
calculation of space-charge forces in
analysis of traveling-wave tubes . D07
estimation of parameters of distribution of a
mixture of two Poisson populations E02
multi-rigid-body attitude dynamics simulation . F06
converting sums to integrals in quantum
statistical mechanics F08
variational calculations for simple approximate
eigenf unctions for an electron in a finite dipole field F09
simplified formulas for calculation of osculating
orbital parameters and range rate of a celestial body . G04
251
Subject Entry
Mathematical Sciences (contd)
multiclass sequential hypothesis test with
applications in pattern recognition Hll
algebraic theory of wideband digital
pseudo-gaiissian noise generator H19
level sets of real functions on the unit square JOB
optimal frame synchronization algorithms K03
conditions for satisfying limiting equilibrium and
velocity equations for mobility on soft sloping terrains K05
system of computer subroutines for
solving initial value problem in ordinary
differential equations K08
method-of-averages expansions for artificial
satellite orbit determination L16
periodic sequences from GF{q) M16
mathematical formulation of double-precision
orbit determination program (DPODP) M29
indefinite integrals of confluent
hypergeometric functions N03
computation of Debye functions of integer orders N04
first-order theory for investigating information
content of a few days' radio tracking data O03
Boolean difference calculus used for detecting
faults in switching circuit gates B02
applications of two-dimensional integral-equation
theory to reflector-antenna analysis R20
recursive algorithms for the summation of certain series SOI
design and implementation of models for double-
precision trajectory program (DPTRAJ) S24
analysis of difl'erenced-range-versus-integrated-doppler
and dual-frequency tracking methods for
determining total electron content of a
time-varying interplanetary plasma V03
use of FORMAC (formula manipulation by computer)
in mathematics of general relativity and in
noncommutative calculus of exterior diflEerential forms WOl
computation of structural modes of a rollout
array spacecraft for attitude-control study W05
analysis of arbitrarily shaped dual-reflector
antennas and their phase and amplitude distributions Y03
integral equations for Green's functions applied to
electron gas problem for study of metals Z02
Mechanics
multi-rigid-body attitude dynamics simulation F06
simplified formulas for calculation of osculating orbital
parameters and range rate of a celestial body G04
252
Subject Entry
Mechanics (contd)
mechanical interaction of a driven roller on soil slopes K05
passive damping of forced precession of a
two-body satellite LH
method-of -averages expansions for artificial
satellite orbit determination L16
mathematical formulation of double-precision orbit
determination program (DPODP) M29
design and implementation of models for
double-precision trajectory program (DPTRAJ) S24
computation of structural modes of a rollout array
spacecraft for attitude-control study Yv'OS
Mechanisms
mechanisms for 66-W/lcg 23-m^ roll-up solar array HIO
Optics
calibration of Mariner Mars 1969 television cameras D02
maximum discriminability versions of Mariner Mars 1969
near-encounter photographs DIO
effect of absorption on scattering by planetary atmospheres Fll
effects of radiation on optical properties of silicon JOS
photometric parameters of outer planets N02
photon energies of a cathode-ray tube system VOl
geometrical optics analysis of arbitrarily shaped
dual-reflector antennas Y0.3
photometric properties of Mariner Mars 1969 television
cameras and of selected regions on Mars Y05
Orbits and Trajectories
Mariner Venus-Mercury 1973 trajectories B14
simplified formulas for calculation of osculating orbital
parameters and range rate of a celestial body G04
orbits and trajectories for Helios Project G06
method-of-averages expansions for artificial
satellite orbit determination L16
mathematical formulation of double-precision orbit
determination program (DPODP) M29
satellite flyby opportunities for outer-planet missions P03
design and implementation of models for
double-precision trajectory program (DPTRAJ) S24
Packaging and Cabling
Space Flight Operations Facility cable control plan .P02
Particle Physics
electron-impact excitation of N2 ■ • . B16
converting sums to integrals in quantum
statistical mechanics F08
253
Sybject Entry
Particle Physics (contd)
simple approximate eigenfunctions for an electron
in a finite dipole field F09
indefinite integrals of confluent hypergeometric functions N03
absolute gamma-ray intensity measurements of a SNAP-15A
(System for Nuclear Auxiliary Power 15A) heat source R04
self -consistent Green's-function approach to
electron-gas problem for study of metals Z02
Photography
Ground Communications Facility television assembly
design for systems development laboratory B12
Mariner Mars 1969 photographic results C22
C24
D04
DIO
LOS
LOS
M34
SIO
S12
calibration of Mariner Mars 1969 television cameras D02
digital processing of Mariner Mars 1969 photographs DIO
R14
synchronization of noisy video M15
Space Flight Operations Facility Mark IIIA user
terminal and display subsystem television monitors T06
software for Deep Space Network video subsystem W04
photometric properties of Mariner Mars 1969
television cameras and of selected regions on Mars Y05
Pioneer Project
Ground Communications Facility television assembly
design for systems development laboratory
to support Pioneer F and G missions B12
Deep Space Network support R07
R08
R09
S14
S15
Pioneer F and G mission descriptions S14
Pioneer F ao.d G spacecraft descriptions S14
rotating antenna tests in simulation
of Pioneer F spacecraft W06
Planetary Atmospheres
neutral atmosphere of Venus studied with radio
occultation by Mariner V F04
254
Subject Entry
Planetary Atmospheres (contd)
effect of absorption on scattering by planetary atmospheres Fll
circular-polarization and total-flux measurements
of Jupiter at 13.1-cm wavelength GIO
photocatalytic production of organic compounds from
CO and HoO in simulated Martian atmosphere H16
Mariner Mars 1969 photographic results L05
LOS
Y05
self -broadened half -widths and pressure shifts for
the R-branch J-manifolds of the Sv^ methane band, which
provides a convenient probe into Jupiter's atmosphere M06
outer-planet atmospheres - N02
high-resolution spectra of Venus ■ Y06
Y07
Planetary Exploration, Advanced
growth of bacteria in soils from Antarctic dry valleys
studied in preparation for detection of life on Mars COl
survival of Antarctic desert soil bacteria exposed to
various temperatures and 3 yr of continuous
medium-high vacuum studied in preparation for
detection of life on Mars C02
study of mechanical interaction of a driven roller on
soil slopes preliminary to construction of
planetary roving vehicles K05
properties of outer planets surveyed in preparation
for exploration N02
satellite flyby opportunities for outer-planet missions P03
Planetary Interiors
outer-planet interiors ■ ■ • . N02
Planetary Motion
motion of outer planets and satellites - . N02
resonances in Neptune-Pluto system W09
Planetary Spacecraft, Advanced
characteristics, capabilities, and costs of solar-electric
spacecraft for planetary missions B06
thermionic-reactor ion-propulsion spacecraft for
outer-planet exploration M25
Planetary Surfaces
growth of bacteria in soils from Antarctic dry valleys
simulating Martian environment COl
survival of Antarctic desert soil bacteria exposed to
various temperatures and 3 yr of continuous
medium-high vacuum in simulation of
Martian environment C02
255
Subject Entry
Planetai-y Surfaces (contd)
Mariner Mars 1969 photographic results C22
C24
D04
LOS
M34
SIO
S12
Y05
outer-planet surfaces N02
Plasma Physics
pumping mechanism of CO2 laser and formation
rate of CO, from CO and O C07
plasma properties and performance of
mercury i.on thrusters M09
electric space potential in a cesium thermionic diode S13
second-order charged-particle effects on electromagnetic
waves in the interplanetary medium V02
analysis of differenced-range-versus-integrated-doppler
and dual-frequency tracking methods for determining
total electron content of a time-varying
interplanetary plasma V03
Power Sources
structural analysis of silicon solar arrays B22
liquid-metal magnetohydrodynamic generator C05
solar cell standardization tests on high-altitude balloons G08
lightweight solar panels H09
design and development of 66-W/kg
23-m- roll-up solar array HIO
effects of lithium doping on silicon solar cells JOS
thermionic-reactor ion-propulsion spacecraft for
outer-planet exploration M2S
absolute gamma-ray intensity measurements of a
SNAP-15A (System for Nuclear Auxiliary
Power ISA) heat source R04
measured performance of silicon solar cell assemblies
for use at high solar intensities R17
electric space potential in a cesium thermionic diode S13
Pioneer F and G power subsystem description S14
computation of structural modes of rollout solar array
spacecraft for attitude-control study W05
Propulsion, Electric
characteristics, capabilities, and costs of solar-electric
spacecraft for planetary missions B06
plasma properties and performance of mercury ion thrusters M09
256
Subject Entry
Propulsion, Electric (contd)
thermionic-reactor ion-propulsion
spacecraft for outer-planet exploration M25
Propulsion, Liquid
fatigue of liquid propellant expulsion
Teflon bladder bag materials C15
computer-controlled operating and data handling system
for quadrupole mass spectrometer to test rocket exhaust H15
structural design and stress analysis computer program
(COMTANK) for advanced composite
filament-wound axisymmetric pressure vessels K06
thrust chamber technology for oxygen
difluoride/diborane propellants R13
Pioneer F and G propulsion subsystem description S14
Propulsion, Solid
solid propellants with reduced burning rates H17
low-acceleration-rate solid propellant
rocket motor and igniter SOS
Pyrotechnics
ignition of low-acceleration-rate solid
propellant rocket motors SOS
Quality Assurance and Reliability
estimation of parameters of distribution of a
mixture of two Poisson populations for statistical
estimation of component reliability E02
Helios spacecraft redundant components G05
Deep Space Instrumentation Facility klystron
testing at microwave test facility JOl
stability comparison of three frequency synthesizers M22
radiometric data accountability, validation,
and selection in real time M24
Ground Communications Facility system tests N06
measured performance of silicon solar cell
assemblies for use at high solar intensities R17
Pioneer spacecraft antenna pointing backup modes S15
Deep Space Network discrepancy reporting subsystem T07
Space Flight Operations Facility central processing
system pre-mission checkout procedures WOT
diagnostics for Space Flight Operations Facility
Mark IIIA central processing system ZOl
Radar
Apollo lunar bistatic radar experiment F05
Venus Deep Space Station (DSS 13)
planetary radar experiments JOl
257
Subject Entry
Radio Astronomy
neutral atmosphere of Venus studied with
radio occultation by Mariner V F04
circular-polarization and total-flux measurements of
Jupiter at 13.1-cm wavelength GIO
Deep Space Network radio science support JOl
L12
planetary masses as error sources in pulsar timings M32
Relativity
mathematical formulation of double-precision
orbit determination program (DPODP) M29
design and implementation of models for
double-precision trajectory program (DPTRAJ) S24
use of FORMAC (formula manipulation by computer)
in mathematics of general relativity WOl
Safety Engineering
safety factois related to predicted and measured
power density description of a large
ground microwave system B07
Scientific Instruments
Mariner Venus-Mercuiy 1973 scientific instruments B14
scientific payload for lunar traverse missions B15
Soil Sciences
growth of bacteria in soils from Antarctic dry valleys COl
survival of Antarctic desert soil bacteria
exposed to various temperatures and 3 yr
of continuous medium-high vacuum C02
microbial and ecological studies of recent cinder
cones at ]3eception Island, Antarctica C03
potassium-uranium systematics of
Apollo 11 and Apollo 12 samples: implications
for lunar material history FOl
measurement of organic carbon in arid soils using
liydrogen-flame ionization detector G02
mechanical interaction of a driven roller on soil slopes K05
Solid-State Physics
cell for measurement of basic electrical
properties of amorphous and polycrystalline
materials under pressure HOI
effects of lithium doping on silicon solar cells JOS
electrical characteristics of AIN insulating films LIO
tests of bolted joints under sustained loading LIS
258
Subject Entry
Solid-State Physics (contd)
effect of tin additive on indium thin-film
superconducting transmission lines Mil
measured performance of silicon solar cell
assemblies for use at high solar intensities R17
self-consistent Greens-function approach to
electron-gas problem for study of metals Z02
Spectrometry
electron-impact spectrometry of N2 B16
evaluation of dependence of ^/(H — H) on bond
angle in alkenes and cycloalkenes C12
computer-controlled operating and data handling
system for quadrupole mass spectrometer H15
radiative lifetimes of UV multiplets in
atomic carbon, nitrogen, and oxygen H20
infrared spectroscopy used to study radiation effects
in lithium-doped silicon J05
self-broadened half-widths and pressure shifts for the
R-branch /-manifolds of the 8^3 methane band M06
outer-planet spectrometry N02
high-resolution spectra of Venus ¥06
Y07
Standards, Reference
Deep Space Network coherent reference
generator and distribution subsystem C14
hydrogen maser frequency standard F03
L19
S30
Deep Space Network timing synchronization
for support of Apollo Project F05
solar cell standardization tests on high-altitude balloons .G08
Venus Deep Space Station (DSS 13)
precision antenna gain measurement .JOl
Venus Deep Space Station (DSS 13)
100-kW clock synchronization JOl
Deep Space Network Tracking System analytic
calibration activities for support of
Mariner Mars 1971 Project M03
stability comparison of three frequency synthesizers M22
time and ephemeris standards used in mathematical
formulation of double-precision orbit
determination program (DPODP) M29
analysis of boresight error calibration procedure for
compact rotary vane attenuators O06
measured performance of silicon solar cell assemblies
for use at high solar intensities R17
259
Subject Entry
Standards, Reference (contd)
time, coordinate, and ephemerides standards and
corrections for design and implementation of models
for double-precision trajectory program (DPTRAJ) S24
noise diode evaluation W02
Structural Engineering
structural analysis of silicon solar arrays B22
lightweight solar panels H09
design and development of 66-W/kg
23-m- roll-up solar array HIO
structural design and stress analysis computer program
(COMTANK) for advanced composite
filament-wound axisymmetric pressure vessels K06
computer program for antenna member size changes L09
tests of bolted joints under sustained loading LIS
evaluation of field measurements of
antenna reflector distortions M05
Surveyor Project
blowing of lunar soil by Apollo 12 onto Surveyor III JOS
Telemetry and Command
teletype configuration in support of ground
communications for Mariner Mars 1971 Project B13
Deep Space Instrumentation Facility near-Earth
telemetry automatic switching unit B19
interplex modulation B20
rate distortion over band-limited feedback channels B21
Deep Space Network support of Apollo Project F05
H07
Deep Space Network support of Helios Project G05
G06
Deep Space Network support of Mariner Mars 1971 Project LOl
synchronization of noisy video M15
Deep Space Network support of Viking Project M30
M31
Deep Space Network multiple-mission command system ROl
Deep Space Network functions and facilities R05
R06
Deep Space Network support of Pioneer Project R07
R08
R09
S14
S15
Deep Space Network support of
Mariner Mars 1969 Project Rll
260
Subject Entry
Telemetry and Command (contd)
telemetry procedural language . S07
operational capabilities of Space Flight Operations
Facility Mark IIIA user terminal and display subsystem ....... T06
processed data combination for telemetry improvement UOl
matched filters for binary signals Z03
Temperature Control
Pioneer F and G spacecraft temperature control S14
Test Facilities and Equipment
apparatus for structural tests of silicon solar
array components B22
apparatus for testing survival of Antarctic desert soil
bacteria exposed to various temperatures and 3 yr
of continuous medium-high vacuum C02
apparatus for determining pumping mechanism
of CO2 laser and formation rate of CO2 from CO and O ....... C07
S-band demodulator for verification of
exciter/transmitter performance F07
measurement of organic carbon in arid soils
using hydrogen-flame ionization detector . G02
high-altitude balloon equipment used for solar
cell standardization tests G08
cell for measurement of basic electrical properties
of amorphous and polycrystalline materials
under pressure HOI
computer-controlled operating and data
handling system for quadrupole mass
spectrometer to test rocket exhaust H15
apparatus for determining product distributions and
relative rates by ion injection H18
wideband digital pseudo-gaussian noise
generator for testing and simulation of
wideband communications systems H19
apparatus for testing radiative lifetimes of UV multiplets
in atomic carbon, nitrogen, and oxygen H20
apparatus for testing bolted joints under sustained loading ....... L15
pulse test apparatus to determine effect of tin additive on
indium thin-film superconducting transmission lines Mil
new, higher performance electric-arc-driven shock tube ........ M19
equipment for testing strapdown, electrically
suspended gyro, aerospace navigation system POl
apparatus for measuring performance of silicon solar
cell assemblies for use at high solar intensities R17
Langmuir probe for testing electric space potential
in a cesium thermionic diode S13
261
Subject Entry
Thermodynamics
shock-tube thermochemistry tables for
high-temperature gases M18
outer-planet thermodynamics N02
computation of Debye functions of integer orders N04
Tracking
teletype configuration in support of ground communications
for Mariner Mars 1971 Project B13
sensitivity of tropospheric range and doppler effects to
shape of rc;£ractivity profile C06
Deep Space Network support of Apollo Project F05
H07
Deep Space Network support of Helios Project G05
G06
Deep Space Network support of
Mariner Mars 1971 Project LOl
Deep Space Network Tracking System analytic
calibration activities for support of
Mariner Mars 1971 Project M03
radiometric data accountability, validation,
and selection in real time M24
mathematical formulation of double-precision
orbit determination program (DPODP) M29
Deep Space Network support of Viking Project M30
M31
digital step attenuator for ranging demodulator OOl
first-order theory for investigating information content
of a few days' radio tracking data O03
Deep Space Network functions and facilities R05
R06
Deep Space Network support of Pioneer Project R07
R08
R09
S14
S15
Deep Space Network support of
Mariner Mars 1969 Project Rll
design and implementation of models for
double-precision trajectory program (DPTRAJ) S24
secjuential ranging using Viterbi algorithm T03
operational capabilities of Space Flight Operations
Facility Mark IIIA user terminal and display subsystem T06
second-order charged-particle effects on electromagnetic
waves in the interplanetary medium V02
262
Subject Entry
Tracking (contd)
analysis of difFerenced-range-versus-integrated-doppler
and dual-frequency tracking methods for determining
total electron content of a time-varying
interplanetary plasma VOt
hi
Viking Project
Deep Space Network support • M30
M31
Wave Propagation
predicted and measured power density description
of a large ground microwave system B07
Deep Space Instrumentation Facility uplink
amplitude instability measurement B17
interplex modulation B20
rate distortion over band-limited feedback channels B21
hydrogen maser cavity tuning servo F03
wideband digital pseudo-gaussian noise generator H19
switched-carrier experiments K07
improved frequency dividers for
hydrogen maser frequency standard L19
microwave transmission through perforated flat plates O05
analysis of boresight error calibration procedure
for compact rotary vane attenuators O06
applications of two-dimensional integral-equation
theory to reflector-antenna analysis R20
sequential ranging using Viterbi algorithm T03
second-order charged-particle effects on electromagnetic
waves in the interplanetary medium V02
analysis of differenced-range-versus-integrated-doppler
and dual-frequency tracking methods for determining
total electron content of a time-varying
interplanetary plasma V03
rotating antenna tests W06
phase and amplitude distribution in arbitrarily
shaped dual-reflector antennas Y03
263
Pyblicatlon Iridex
Technical Reports
Number Entry
32-1408, Vol. V M18
32-1413, Supplement 1 D06
32-1503 Y03
32-1513 L16
32-1516 F06
32-1518 . H15
32-1519 H09
32-1522 GDI
32-1524 C02
32-1527 M29
32-1528 B22
32-1529 N02
32-1530 G08
32-1531 K06
DSi Progress Report for January-February 1971
(Technical Report 32-1526, Vol. I!)
JPL Technical Section Entry
316 SFOF/GCF Operations B13
264
J PL Technical Section Entry
318 SFOF/GCF Development H03
L04
P02
vol
W07
331 Communications Systems Research LIS
H9
M13
M14
R02
S30
T03
332 DSIF Engineering L09
M05
M17
333 Communications Elements Research . ■ • F03
O05
R03
335 R. F. Systems Development C14
337 DSIF Operations .B17
B19
UOl
391 Tracking and Orbit Determination V02
401 DSN Engineering and Operations Office H07
K03
M02
M23
T07
420 Mission Support Office G05
M30
R05
S14
265
DSN Progress Report for March-April 1971
(Technical Report 32-1526, Vol. Ill)
JPL Technical Section Entry
315 Flight Operations and DSN Programming S07
W04
316 SFOF/GCF Operations T06
318 SFOF/GCF Development B12
K02
L03
N06
S16
ZOl
331 Communications Systems Research E02
H19
J06
M15
M22
Z03
332 DSIF Engineering M20
P04
S19
W03
333 Communications Elements Research L12
O06
W02
335 R. F. Systems Development F02
F07
JOl
K07
OOl
W06
266
JPL Technical Section Entry
337 DSIF Operations .L12
391 Tracking and Orbit Determination C06
M03
O03
V03
401 DSN Engineering and Operations OfiGce ..... A02
M24
ROl
420 Mission Support Ofiice G06
LOl
L12
M31
R06
S15
Technical Memorandums
Number Entry
33-426, Vol. VI . . .R07
33-426, Vol. VII R08
33-426, Vol. VIII R09
33-433 . . . .B07
33-451 S24
33-452, Vol. 11 .F05
33-467 .J05
33-471 .POl
33-473 ,R17
33-474, Vol. I .Rll
33-476 .W05
33-477, Ft. I .K05
33-478 .R20
267
Nymber Entry
33-479 K08
33-480 S13
33-481 G04
33-482 Hll
J PL Quarterly Technical Review, Vol. 1, No. 1
JPL Technical Division Entry
131 Advanced Teclmical Studies OfBce B15
290 Project Engineering B15
320 Space Sciences B15
WOl
330 Telecommunications B20
D07
L17
340 Guidance and Control HIO
350 Engineering; Mechanics O02
360 Astrionics B03
370 Environmental Sciences M19
380 Propulsion COS
CIS
H17
101
M08
SOS
390 Mission Analysis P03
Open Literature Reporting
AIAA J. Entry
Vol. 9, No. 2, pp. 205-212 M09
Vol. 9, No. 2, pp. 345-347 BOl
268
Am. J. Phys. Entry
Vol. 39, No. 1, pp. 116-117 .F08
Ann. Geopbys. Entry
Vol. 26, No. 1, pp. 201-207 ,B16
Astronaut. Aeronaut. Entry
Vol. 8, No. 1, pp. 52-59 B14
Astron. J. Entry
Vol. 76, No. 1, pp. 12-16 . .GIO
Vol. 76, No. 2, pp. 123-140 F04
Vol. 76, No. 2, pp. 167-177 W09
Astrophys. J. Entry
Vol. 165, No. 1 Pt. 1, pp. 105-107 M32
Chem. Technol. Entry
Vol. 1, No. 2, pp. 122-126 R12
Ecology Entry
Vol. 51, No. 5, pp. 802-809 .COS
Icarus: Int. J. So!. Sys. Entry
Vol. 11, No. 3, pp. 390-407 Y06
Vol. 13, No. 1, pp. 58-73 .Y07
IEEE Trans. Inform. Theor. Entry
Vol. IT-17, No. 1, pp. llft-112 .B21
J. Am. Chem. Soc. Entry
Vol. 93, No. 4, pp. 928-932 H04
J. Appl. Phys. Entry
Vol. 42, No. 1, pp. 97-102 .Mil
Vol. 42, No. 3, pp. 1016-1020 . . , .C07
269
J. Chem. Phys. Entry
Vol. 54, No, 3, jDp. 843-849 H18
J. Combin. Theor. Entry
Vol. 10, No. 1, pp. 80-91 M16
J. Geophys. Res. Entry
Vol. 76, No, 2, pp. 293-296 LOS
Vol. 76, No. 2, pp. 297-312 L08
Vol. 76, No. 2, pp. 313-330 M34
Vol. 76, No. 2, pp. 331-342 SIO
Vol. 76, No. 2, pp. 343-356 C22
Vol. 76, No. 2, pp. 357-368 S12
Vol. 76, No. 2, pp. 369-372 C24
Vol. 76, No. 2, pp. 373-393 D04
Vol. 76, No. 2, pp. 394r417 R14
Vol. 76, No. 2, pp. 418-431 D02
Vol. 76, No. 2, pp. 432-437 Y05
Vol. 76, No. 2, pp. 438-472 DIO
Vol. 76, No. 3, pp. 732-735 Fll
J. Quant. Spectrosc. Radiat. Transfer Entry
Vol. 11, No. 1, pp. 69-73 M06
Vol. 11, No. 1, pp. 81-91 H20
J, Res. NBS, Sec. B: Math. Sci. Entry
Vol. 74B, No. 2, pp. 85-98 N03
J. Spacecraft Rockets Entry
Vol. 7, No. 12, pp. 1379-1390 B06
Vol. 8, No. 1, pp. 4-14 R13
Vol. 8, No. 1, pp. 41-47 Lll
Vol. 8, No. 2, pp. 196-198 B02
Vol. 8, No. 3, pp. 295-297 M25
270
J. struct. Div., Proc. ASCE Entry
Vol. 97, No. ST3, pp. 905-933 .L15
Math. Comp. Entry
Vol. 24, No. 110, pp. 405-407 N04
Met. Trans. Entry
Vol. 2, No. 3, pp. 673-676 LIO
Nucl. Sci. Eng. . Entry
Vol. 43, No. 3, pp. 267-272 . . . .R04
Org. Mag. Reson. Entry
Vol. 2, No. 5, pp. 511-525 C12
Phys. Rev., Pt. A: Gen. Phys. Entry
Vol. 3, No. 1, pp. 13-15 F09
Phys. Rev., Pt. B: Solid State Entry
Vol. 2, No. 11, pp. 4445-4460 Z02
Proc. Nat. Acad. Sci. Entry
Vol. 68, No. 3, pp. 574-578 H16
Rev. Sci. Instr. Entry
Vol. 42, No. 3, pp. 393-394 HOI
Science Entry
Vol. 171, No. 3969, pp. 282-284 FOl
Vol. 171, No. 3973, pp. 798-799 . . . . , .J03
SIAM J. Math. Anal. Entry
Vol. 2, No. 1, pp. 31-36 SOI
Soil Sci. Entry
Vol. Ill, No. 3, pp. 175-181 G02
271
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