AA. lvsoxes

JET PROPULSION LAZORATORY TBENOPFICE MEMO
7 Me. Eimer FROM G. lo Hobby _ DATS Novenber 3, 1960
SUBJECE A Device for the Detection of Microorganisms in the Martian

 

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The device will collect fine dust particles fren the Martian

etmoaphere.
The perticles will be iumoculated inte mall chembers which

wili contain o varlety of types of liguld media.
ts will. be macs of the imoculated

 

Optical turbidity meas
chenbers et programned intervals to determine increases in
particle number.

pH changes in the media wil aleo be measured at programmed
datexvals to detect possible metabolic activity of the innoc-
ulated particles.

System Deseription

ae

Esuple Collector

The general requiremente of the collection, mechaniam are as

follows :

&.  Frovide the capability of sempling relatively large volunes
of the Mertian etmosphere in order to compensate for possible
low concentrations of viable particles. (Ten to eueinty-five.
liters)

be Diseriminate between particle sizes. Size of particles
must be optimum Dr imecculation into chaubers end for baving
@ high probability of heving « large amber of absorbed
microorgenions.

ce The mamer of semple collection should be consistent with
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simple end effective imoculstion of the growth chambers.

Zmmoculation Systen

Bo

dv.

The systen must be designed to permit unsealing and resealing
of growth chambers before snd after imnoculation.

Imoculun mst not interfere vith subsequent optical turbidity
measurements, or pH measurements.

The amount Of iumoculus my range from 0.1 to 1.0 ce per
chamibex’«

Growth Chamber

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Each chamber will provide for 1 milliliter of mediun plus
inneculated sample.

Walls of chamber must be chemically inert. Toxleity tests
ahould be designed for transit time to Mars or longer,

(200 to 250 days).

Walls of chamber not used in optical observations should
hewe very low reflection coefficient.

Chembers must permit optical turbidity measurenents.
Chambers should include electrodes or other system for pi
Total system should consist of 50 to 100 (or more) chambers.
Configuration of the chambers mst consider minimm volume
requirenents and be consistent with a progremmed sceming of
the total chamber system for optical turbidity and pH measure-
mazes .

All growth chanbers in the system met have the capability of
being gealed before and after imoculation.

Detecter System

Turbidity
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~3-

1) Only changes in forward scattering of light should be
measured.

2) Light source mst be miniaturized and of low pover con-
sumption.

3) Idight detector of small size, (possibly photoconductive,
FoS, PbSe, or CdSe).

5H Neagurenent

1) Range: 1-14

2) Sensitivity: 0.5 pH unite

3) Measurements mist be made in chamber while sealed.