MARINER B ENTRY CAPSULES - SCIENTIFIC SUBSYSTEM

R. K. Sloan

Outline for Discussion
I. General philosophy

A. The Split capsule concept
B. Scientific objectives
C. Criteria for selection of experiments

II. The capsule system
A. Capsule-bus interface
B. Trajectories
C. Configuration
D. Weight
E. Power
F. Communication
G. Program of operation
H. General problem areas
1. Sterilization
2. Won-magnetic components
3. Long operational lifetime

Ill. Scientific experiments - description
A. Biology
1. Mualtivator
2. Radiochemical growth probe
3. Microscope
4. Gas chromatograph

B. Atmospheric thermodynamics
l. Temperature
2. Pressure
3. Density
4 Sonic Velocity

C. A,mospheric composition
1. Gas chromatograph
2. Mase spectrometry

3. “Simple composition
4. Experimental philosophy

D. Visual observation
1. Television
2. Facsimile camera

E. Radiometric observatton
1. Wide band spectrophotometer
2. Ultra violet photometer
3. Surface induction electromagnetic probe
4. Surface photometer

F. Accessory instrumentation
1. Altimeter
2. Accelerometers
3. Structural thermometers
Iv.

Scientific subsystem for various capsule types

A. The 18 capsule configurations
B. Mare capsules
C. Venus capsules
D. Summary end comments
Scientific packages - recommendations
A. Mars
1. 1964-65
2. 1967
B. Venus
1. 1964
Zz. 1965-66
3. 1967
Appendices
A. Model atmospheres of Mars and Venus
3B. Graphs and figures
Cc. Caleulations
BD. Cognizant personnel
R. References
F. Attachments
Scientific objectives

1.
2.
3.

4

Increasing the knowledge of the planet in general

Biological information on Mars is the prime objective

For Venus the prime objective is a profile of the thermo dynamic
variables

Photographic observation should be included as soon as it is feasible

Criteria for selection of capsule science

1.
‘ 2.
; / 3.
. 4,
: -$.
( 6.

Nw 7

Reliability of operation

No ambiguity of interpretation of data

Sterilisability of all components, especially for Mars
Compatability with syetem constraints

Reasonable evolution of knowledge

Importance in the development of spacecraft technology
Experiments that must use « capsule
Multivator

The multivater is an instrument which measures several biologically impor-
tant parameters of the planetary envirooment. The original concept is due to
Dr. Joshua Lederberg of the Stanford Exobiology Laboratory and the present
design of the instrument is proceeding under the supervision of Mr. Jerry Steart
of JPL.

The multivater consists of eighteen identical celis in which specific
chemical, biochemical, and physical measurements can be performed. Rach cell
conaists of two chambers, one of which can be innoculated by a sample of
planetary soil while the ether contains identical reagents or probes which
react without the presence of soil end thus previde a control measurement.

The reagents are stored in hermetically sealed time release capsules and
released upon initiation of operation. The eighteen cells are mounted on a
circular structure and are rotated in sequence into position for sampling. All
experiments are designed so that sampling is done optically using either
specific spectral responses or scintillation counting of tagged radio chemical
isotopes. The present design accomplishes the soil sample collection and injection
by placing s soil sample in a hopper situated in the center of the structure,
and centrifuging it through a hollow arm at the end of which is a mechanism for
picking up a single cell. By this method the cells are innoculated in
sequence. The centrifuge also supplies the opportunity to accelerate sedi-
mentation or mixing processes when it is desired. Methods of soil sampling
which carry the soil from the planetary surface to the multivator hopper are
being investigated in conjunction with various possibilities presented by the
capsule configuration.

Table ( ) indicates preliminary ideas outlined by Dr. Lederberg of the

parameters to be investigated in the individual celle.
Cell

10

ll

12

13

14

15
16
17
18

Clase of reaction

Physical

Rasywe

Rusyme
Ensyme
Easyme

Metabolic
Metabolic
Metabolic
Metabolic

Fiuerescent

A

My

Table 1
Specific test
pl, conductivity,

turbidity mass

RMA ase

Protein ase

D-epolypeptide
(optical emine)

glucose

lactic acid

complex- peptone

syathetic L-glucose

XY enapthyl phosphate
. (acid substrate)

‘~ onapthyl phaephate
{alkaline substrate)

Mac leotidease-napthyl

thymiilylate

RMA & DMA breakdown

(ester)

Leucine amino
peptidase

 onapthyl-sul fate

‘X onapthyl butyrate

choline esterase

Sh -napthyl glucosidase

Means of Detection
electrode

dialysis membrane + cl4
in COp detected by
ecintillation

¢
"

spectrally sensitive
to = 3368
= 460 =
The basic multivator without sampling device or internal orientation
mechanization) weighs five (5) to six (6) pounds, consumes six (6) watts of
power average, uses an information rate of about one (1) bit/sec, requires
orientation to within 15° to the gravitational vertical, and needs « mininun
of two (2) hours operating lifetime on the planetary surface. If orientation
and externsl sampling must be integral to the instrument the weight and power
increase by about a factor of two.

There are obviously many problem areas involved in this instrument and
some of these should be mentioned. 1) The reagents used canact meet the space-
craft specifications for sterilization of 135°C for 26 hours. This is most
serious but somewhat amusing since the object of the sterilization program is
to maintein the virgin biological environment so that experiments like the
multivator will give meaningful results. This state of affairs may persist
fez all possible biological experiments. We insist upon sterilization so that
we can perform our biological experiments upon an uncontaminated environment,
but then the spacecraft system designers, after accepting this sterilization
constraint, prohibit biological experiments from flying because they are un-
sterile. The only solution is the multivator steribity must be guarenteed.

2) The reagents must not decompose over the capsule lifetime of 6 to 8 months.
3) So far no acceptable method of sample acquisition has been devised. 4) The
presence of the centrifuge motor may prevent the instrument from meeting the space-

craft magnetic specifications.

Modified aultivator
Radiochemical Growth probe

This is an instrument which innoculates a radioactively tagged growth
medium with planetary soil end measures cl4o, metabolized by any organiems that
may be present in the soil. It was conceived by Dr. Gilbert Levin of
Resources Research, Inc., and developed by him under a MASA contract.

After the operation sequence is initiated a projectile carries a long
etring over the planet surface, This string is reeled back carrying soil
particles into the growth chamber which contains a universal media whose
organic components are tagged with carbon-14. After soil innoculation the
chamber is sealed and the fertile sample metabolizes the radioactive material
giving off cl4o,, earbon-14 dioxide. The clo, passes into a detection chanter
and the radioactive counts are sampled for short times at hourly intervals and
a@ growth curve is plotted. <A positive result combined with a suitable
control would indieate the presence of semi-terrestrial type life.

The instrument weighs less than one (1) pound, consumes less than one watt
of power, requires a negligible data rate, does not require precise orientation,
and needs at least two (2) hours of operating lifetime on the planetary surface.

There are several basic problem areas associated with this instrument. 1) As
for the multivator, sterilization may present a difficult hurdle. 2) Controls
are needed to show that the growth observed is due to external microorganisns.
3) The media that is used provides @ limitation on what types of organisms are

detected.

Microscope

An abbreviated microscope used to view microorganisas and particulate matter
present in the planetary atmosphere has been proposed by Prof. J. Lederberg of
Stanford University and Dr. G. Seffea of JPL.
The microscope will collect aerosols and dust during parachute descent of the
capsule, separate them by density, and observe the lighter particles via a
simple lens and vidicon system. The optice will have a fixed focus and illumina-
ting syatem and will examine an object field of 100 microns with a resolution of
0.5 microns. Phase contrast will be used if possible. ech picture will consist
of 80,000 bits of information using a square, 200 line raster and four shades of
gray.

The recognition of microbes under a microscope is not simple but certain
features are strongly indicative. Most terrestrial forms have a regular
geometrical shape and occur within a certain size. Many organisms and cells
contain internal organelles or intricate architecture. If such were observed,
it could in some cases establish, beyond eny reasonable doubt, the presence of
life.

It ie estimated that this instrument be designed to weigh less than
three (3) pounds, occupy a volume of less than 500 cubic inches, require less
than one watt for illumination, can be made rugged and sterilizable, and can
remain in standby conditions for at least 300 days.

There are two major problem areas, 1) requirement of either a high data rate

or on board storage, 2) relisble sample acquisition and handling.

Gas Chromatograph (biclogy)

The gas chromatograph is more fully discussed under the atmospheric composition
instruments and is included here to emphasize ite application to the detec-
tion of organic compounds that would be indicative of the state of
evelution of planetary life. It presents the advantage of studying the biochentcal
eavironment and obviates the necessity of assuming terrestrial type life in the
design of biological experiments. The "biological" gas chromatograph differs from
the atmospheric g-c mainly through the sampling mechaniom and the choice of

columme.
Temperature

The temperature will wary from 100°K to 3000K on Mare and from 200°K to
more than 600°K on Venus, depending upon the height in the atmosphers, the
latitude of capsule entry, and local planetary "daytime." Since latitude and
local time cannot be known within wide limits for the Mariner B capsules, a few
Spot measurements of temperature at various altitudes ere clearly meaningless.
Bowever, these variations in local conditions probably will mot affect the general
temperature profile of the atmosphere which should be relatively constant over
the planetary sphere. Thus temperature measurements must be correlated with
simultaneous height determinations. The radar altimeter discussed in another
section provides a straightforward approach to height measurements. If this is
unavailable, height information must be deduced indirectly by integration of the
hydrostatic equation. Appendix C indicates the method and a sample calculation.
Temperature measurements during descent must be made such that the distance between
semplinge does not exceed 500 feat.

The thermometer will be either a thermistor type of a fine tungsten resistance
wire. Preliminary studies indicate that the latter would have « shorter respense
time and be less sensitive to non-atmospheric heat gources. For Mars the
dynamic range should be from 100°K to 300°K with an accuracy of about + 1%,

For Venus the range should be 200°K ¢o 1000°K with an accuracy of + 5°K. The
difference in accuracies reflects the fact thet the knowledge of Mars is consider-
ably more precise than that of Venus.

Weight and power are minimal, (a few grams and less than 1 watt), the data
rate depends upon descent velocity but should be about 1 bits/eecond. The thermometer
should operate continuously during descent and after impact to pick up height
variations and diurnal changes.

The main problem area is selection of appropriate mounting on the capsule
structure so that the temperature that is measured is truly the ambient tempera-

ture.
JPL is presently requesting design study contracts for construction of this
instrumentation. It is felt, due to the intimate relationship between the thermo-
meter and the capsule design, that this program should proceed with close liaison

between the experimenter and the capsule design engineers.

Pressure

The pressure on the Martian surface is between 50 and 100 millibars with a
nominal value of 65 mb. Important parameters to measure are the pressure profile,
the surface pressure, surface diurnal and seasonal pressure variations, and short
term pressure fluctuation. The surface pressure is critical in calibrating
spectrometric measurements taken by the bus. The pressure profile is interesting
in iteelf and in conjunction with the temperature measurements permits a relative
height determination through integration of the hydrostatic equation. The
pressure variations mentioned above are probably second generation experiments.

Oa Venus the surface pressure is unknown. Estimates that it is several
tens of atmospheres are common. As with temperature, the surface pressure on
Venus will be extremely critical in the design of future soft landing spacecraft
eo that knowledge is necessary as soon as possible.

Preseure measurements should be taken simultaneously with the temperature
measurements. The type of transducer has not been selected and may be quite dif-
ferent for Mars and Venus. Weight, power and communication requirements are
similar to the thermometer as is the necessity for correct placement on the
capsule structure. The dynamic range on Mars should be from 0 to 150 mb with
an accuracy of + 1 mb. On Venus the range would be from 0 to 200 stmosphere
(probably two transducers) with an accuracy of 24 from 0 to 1 atm. and + 1 atm.
in the rest of the range.

Contrary to the situation with the temperature, a few isolated pressure
semplings would be valuable, especially if they were made at the surface, since
the pressure variation over the sphere would be comparable to the fluctuations of

pressure at a single point. As with the temperature, if the surface relief is
large, ambiguity will result in the interpretation of surface preseure data.
JPL is presently requesting design study contracts for construction of this

instrumentation.

Density

In conjunction with pressure and temperature, and, assuming the perfect gas
lew, the deasity will give the molecular weight which will provide a rough
indication of the composition. 8e far the only instrument proposed is an electron
absorption apparatus which has been developed for terrestrial atmospheric density
measurements up to 150,000 feet.

The gauge consists of a source of bete particles separated from a detector
by a fixed distance. The beta ray attenuation coefficient is relatively indepen-
dent of composition for the items of interest. Weight lese than 1 pound, power is
less than 1/2 watt, information rate is comparable to temperature and
pressure instrumentation. The same system integration problems ere anticipated
as with the other thermodynamic measurements.

JPL is presently requesting design study contracts for construction of

density measuring instrumentation,

Velocity of sound

Many proposals have bess made using the measurement of the velocity of
sound as a probe for compositional and thermodynamic parameters. The basic
equation is ve = os where % is the effective ratio of specific heats, R is the
gas constant, T is the absolute temperature and M is the effective molecular weight.
Since T and M will be measured by other parts of the thermodynamic package, measuré-
ment of v will indicate a value for & - Thus we will know both % and M and the
possibilities for various compositions will be narrowed considerably. Appendix
C indicates quantitatively how good this knowledge will be for the various

aseumed compositions.
The instrument should operate using resonance of standing waves since this
is most reliable, easier to mechanize, less subject to instrumental effects,
and leas dependent upon external conditions. It is hoped that the system require-
ments will be similar to other thermodynamic instrumentation.

J¥L is presently requesting design study contracts to develop this instrumen-

tation.

Gas chromatograph (atmospheric composition)

The gas chromatograph separates various components by using their different
retention times in an adsorption or fine capillary column. By suitable colum
selection almost any moleculer or atomic species can be investigated. The feasi-
bility of incorporating this instrument in a spacecraft has been extensively
investigated in connection with the Surveyor program. The planetary instrument
will investigate the following gases with emphasis on those marked by an asterisk;
M2*, CO.*, A*, N20", 02%, CO*, CH,*, Ho, 0,%, WM,*, Hg8, nitrogen oxides, CoM,,
Kr, Xe, He, Ne. The limit of detection is 10 ppm at the surface level.

The instrument is designed to operate both during descent aad after impact.
Weight is less than 5 lbs., power is four (4) watts. Each sampling requires «
total of 400 bits of information.

Two possible problem areas are 1) sufficient equilibration time prior to
Operation, 2) sampling.

The gas chromatograph is capable, with suitable modification of the sampling
system, of making complete organic and inorganic analysis of the planetary soils.
The program is supervised by the joint efforts of Mr. Vance Oyama of JPL,

Prof. James EB. Lovelock of Beylor University and Prof. 8. R. Lipsky of Yale

University.
Mase spectrometer

The mass spectrometer can detect compounds, atoms, and isotopes present in the
planetary atmosphere. This device is being developed extensively for use in terres-
trial sounding rockets. Several types of instruments are being considered,
magnetic sector, quadrupole electrostatic mass filter, r-f spectrometer, and various
other applications of the time of flight principle.

JPL has released a request for design study for a spectrometer that meets
the following constrainate:

Weight - five (5) pounds or less

Power - six (6) watts or less

Sensitivity - 0.1 volume percent components

Accuracy - + 10% on 10% components

+ 3% or better on 80% components

Resolution - M/ 5 M= 25 or better

Mass range - 12-50 amu

Scanning time - 20-60 seconds

Sampling - one or more samples repeesentative of the planetary atmosphere.

“Simple” composition

Simple composition refers to the concept of building separate small instru-~
ments to measure wpecific components of the planetary atmosphere. These sre
designed as a backup to the complete spectrum instruments like the gas chromato-
graph or the mase spectrometer and will be included on the capsule if systen
constraints prohibit the inclusion of these more complicated instruments. JPL ha s
received and reviewed proposals to build instruments to detect H20, 02, 03, co?
and Ng. They all meet the desired constraints of | pound, 1/2 watt, and minimua

data rate specified by the JPL request.
Experimental philosophy

At present it is impossible on technical grounds to choose which of the three
approaches to compositional analysis should be selected for flight items.
Aseuredly they each will be included in some future mission so that preliminary
study of each is warranted. After the completion of the design studies a choice
will be made as to which of the three will be selected for breadboard construction

and flight. Only one can be flown.

Television

Me studies are underway to include a television system on a Mariner B
capsule in 1964. Almost certainly, however, later editions of the capsule which
have a greater communication capability will carry a TV system. Television
technology is well advanced, however, so that it could easily be incorporated
at any time the system would permit. The instrument parameters would be adapted

to fit the total mission constraints.

Vacsimile camera

The attached JPL interoffice memo (Appendix F) discusses an exciting device
which could with only slight modification be incorporated in the 1964 Mariner B
capsules. This device would transmit a complete, 360° picture of the capsule
horison plus resolution of the local capsule area to a few millimeters. It
would also be an absolute photometric device that would measure reflectivities,
solar radiation, and atmospheric transmission. Some color indexing may also be

possible.
Wide band spectrophotometer and UV photomater

Thie instrument would use the Sun as @ source and measure the transmittance
of the planetary atmosphere in several selected wide wavelength regions. This
measurement would provide, in rough fashion, the following information:

1) Surface ultraviolet radiation intensity whose presence is inimical to living
orgeniems as we know them, 2) osame content of the atmosphere (UV spectrophoto-
meter), 3) radiation data for computation of meteotological models, 4) visible
windows in the Venusian atmosphere whose presence would permit surface surveys from
flybys or orbiters, 5) the presence and possible composition of clouds.

Major problem areas are: 1) The elevation of the Sua would be unknown so
the instrument must operate the same with radiation from anywhere in the hemis-
phere of view, 2) Atmospheric scattering, 3) Filter selection and design.

At present, no work is being done on an instrument of this type. Interested

scientists should be encouraged to participate in this vital measurement.

Rlectromagnetic induction of the surface

This instrument would measure the intensity and phase of electromagnetic
waves scattered from the planetery surface. Qualitative measurement of soil
type and wetness should be feasible. This experiment was proposed by
Dr. Elliott Leviathal of the Stanford Exebiology Laboratory. The Conductron
Corporatéon has studied the feasibility of inetrumentation and concluded that
an instrument weighing $ lbs and consuming 9 watts can perform the job. They
have presented preliminary data indicating how the measured parameters correspond
to various soil types end wetness.

It ie improbable that the instrument can be carried on the 1964 capsules.