STANFORD UNIVERSITY
STANFORD, CALIFORNIA

DEPARTMENT OF GENETICS
School of Medicine

cc; Hug he 3

March 3, 1959

Dr. Bruno Rossi

Physics Department

Massachusetts Institute of Technology
Cambridge 39, Mass.

Dear Dr. Rossi:

| have, believe me, been working very hard on the proceedings of our
recent committee meeting at Stanford for consideration of planetary biology.
(May | as jargon call this Westex, and the group in your locality, of course,
Eastex). As | wrote you earlier, most of our time was devoted to questions
of contamination, owing to the imminence of CETEX and of Pioneer IV. We hope
to meet again on March 21, at JPL in Pasadena to take advantage of the oppor-
tunity of seeing this development laboratory in operation. We expect now to
stress the more constructive issues, especially having had some indoctrination
and time for meditation.

| should like to stress that the group agreed on a very firm stand on con-
tamination, that we would consider it '' a scientific catastrophe and an act of
unconscionable irresponsibility'' to permit the deposition of a single viable
microorganism on the surface of Mars or Venus, pending further information on
the habitability of these planets by terrestrial microorganisms. We have not
received adequate information (and perhaps it does not exist) on the effects
of impact with the surface or of atmospheric friction as would allay the
Gears of contamination by an uncontrolled mission. However, the group felt
that a program of microbiological control could and should be initiated that
might demonstrate the feasibility of sterilizing an experimental mission to
determine the physical conditions that would control possible habitability.
This would involve the use of modern, effective methods of fumigation and
empirical verification of their total reliability when applied to sample
missiles. It is only commonsense that the first approaches to these planets
should be designed to obtain as much information as possible without
impact, but the same precautions must be taken to guard against the conse-
quences of accidental landing. Pre-sterilization might be coupled with a
structural design that would assure complete incineration by atmospheric
friction for these first approaches. I trust that these representations
will be in mind not only for CETEX but also for the US NASA plans for Venus
shots this June as have been announced by Repr. Brooks.

We suggested that the microbiological research installations at Fort Detrick
(cf. Or. Riley Housewright) and perhaps the Q'master corps labs. at Natick, might
be in a favorable position to assist on the control program.

The Westex group was somewhat less emphatic as concerns the moon as a target--
less, | feel, perhaps as a measure of scientific caution as of the impression
that it might have to be bargained away in order tooensure the integrity of
other planetary objectives. 1 do not entirely share this hesitation, as | feel
that the primacy of scientific studies of 'life on other worlds'' will not be
contested by anyone in a responsible position,

Ochi 5 he

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Our present conception of lunar conditions does not permit of the
possibility of growth and spread of terrestrial organisms, and the
moon is therefore substantially less sensitive as a target than are
Mars and Venus. There was some spread of opinion as to the level of
deposited biological material (dmviable or not) that would constitute
ultimately detectable, hence signfficant residues of contamination, ranging
from 102 to 10!9 microorganisms per missile. Certainly, by present methods
a live (though dormant) bacterium or spore would be the most readily detected.
Our considered recommendation was therefore (1) that moonshots also be sub-
jected to effective sterilization procedures, and (2) that the level of con-
tamination before sterilization be minimized by clean technique, to not
more than 18 per missile. From the technical outlines furnished us by
Hibbs and Davies, we felt these were quite reasonable limitations and could
be met by reasonable diligence without interfering in any way with the
engineering program,

The group as a whole was NOT willing to dismiss the possibility of
interplanetary transport of spores, having taken into considered account
the telling arguments of radiation inactivation and the difficulties of
escape. Such transport is considered most unlikely on present knowledge.

Present conceptions of the lunar surface may have to be applied less
dogmatically until more information is available from closer approaches. This
is illustrated by the fact that the persistence of a local atmosphere (e.g.
Alter and Koryzev's observations) can be controversial. The generalizations
that have been formulated about temperature ranges, exposure to solar radiation
and so forth may well apply to average conditions, and may not preclude local
exceptions. If there can be any question of persistent moisture from internal
sources, and this would be utterly preposterous except for Koryzev's claims,
the moon might surprisingly prove to be a sensitive target, along with the
other mp planets. A similar agnosticism should be applied to predictions of
universal conditions on the surfaces of other planets, e.g., the supposed
high temperatures prevailing on Venus.

Together with precautionary measures for sterilization, we recommended
a detailed molecular inventory, so that later planetary investigators might
more easily identify fragments of organic material, alloys, etc. as having
originated from a previous missile. This inventory should include all intended
components of the missile in terms of atomic and molecular composition and their
amounts, and also as accurate estimates as can be made of adventitious materials:
dirt, lubricants, fumigants, propellants and particles that may be taken up in
Flight.

New research is needed to furnish information in the following areas, apart
from the obvious necessities of astronomical data:

1) The effects of impact of a missile: particularly dispersion and heating
Of various components.

2) Flux and penetration of solar UV, X-ray and corpuscular radiation in transit.

3) Incineration of missiles in planetary atmospheres (presumably not complete
in view of survival of meteoritic earthfalls.)

4) Methods of fumigation of missile payloads and of microbiological control.
Waeatew 1D

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Camments on Cetex-1 report, as published in Science, Oct. 17, 1958

1) The committee felt it would be difficult to place sufficvent stress

On the importance for thedretiéal biology of unimpeachable evidence on

the status of life on other planets. We now have an increasingly plausIble
picture of the steps whereby life evolved on earth, so that we have strong
expectations for parallel developments elwewhere, wherever the availability
Of carbon compounds (which must be universal), water or other solvents, and
temperatures in a suitable range are compatbble with the evolution of chemi-
cal complexity in organic (carboniferous) compounds, The iénspoiled state
of the surfaces of the other planets may be the only means available to the
human species ever, and certainly for many years to come, whereby these
speculations can be tested by explicit observation,

Laymen and other scientists may be expected to be equally strongly moti-
vated by a fundamental curiosity as concerns the uniqueness of life in the
universe to recognize planetary biology as one of eth most fundamental Issues
in space exploration that will persist when most of the momentary pressures
have been forgotten in the perspective of history,

If any errors of judgment are to be made, clearly they must be conservative
Ones. Would this generation of scientists ever be forgiven by its successors
if at permitted the execution of a cosmic blunder that could gamkzx be remotely
anticipated? By their very nature, experimental missteps in biology may do
irreversible harm; in the physical sciences they may lead at most to exasperation
delay and waste.

On the whole, we believe it necessary and possible to formulate a program
of Space research that conserves objectives in biological science without im-
peding sober objectives in the physical sciences. Indeed, the two programs are
not fundamentally separable,

2) The XMXEXHEXXKM Cetex report is a caarifying document that does much to
place the start of planetary biology and chemistry in reasonable perspective.

We would, however, take exception to some particular points that warrant further
discussion:

A) ‘any contamination of the (moon) dust by space operations will be
localized.'...owing to the low density of the atmosphere.

This premisex is fundamental to a number of assurances concerning the
safety of lunar probes, but can it be supported? No particle will reach the
moon's surface with less than escape velocity. Any fragment which recoils
having dissipated half or less of its kinetic energy will have suffieient
velocity to orbit the moon. Residual energies of less than half will allow
for parabolic trajectories to ranges approaching the whéle perimeter. The
absence of an atmosphere allows for the prompt dispersal of parts of the
missile, to any point on the moon's surface. This supposition is comcordant
with the widely accepted interpretation of the lunar rays, especially Tycho,
precisely as the result of fallout from meteoritic infalls. These rays may
extend for thousands of kilometers! (cf. Baldwin, The face of the moon, 1949).

(A more cogent expectation is that any uncontrolled impact may result in
the dissipation of most of the kinetig energy as heat. If this can be sub-
Stantiated for lunar impacts, there would be no danger of biological contami-
nation. However, it appears to be uncertain whether we could rely on impact-
heat sterilization of the entire payJoad; indeed those fragments that were
most widely dispersed might be expected to be heated the least, since they would
have dissipated less of their infal f energy on the impact. This question plainly
has not been exhausted, ) ;

Other means and assurances of localization of missile components must be
found,

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B) Solar radiation would decompose biospores just as it decomposes cosmic

dust....
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This may be granted for exposed particles lying on a hamagenasus, unprotected
surface, The point of exception is obvious. the moon is not such a surface.

lt is of course a serious criticism of panspermia, how can a biospore transit
the solar radiation field to reach another ppa planet without being destroyed. To
sustain the hypothesis we might have to plead that the spore is embedded in some
other protecting material, e.g., mux a particle of clay, or else that some hitherto
unknown optical property of the spore in high vaceum might furnish some protection.
The former plea makes it more diffiuclt to accept Arrhenius’ proposal of radiation
pressure as the impetus to interplanetary transit. All this admitted, we do not
feel that we have the intimate knowledge of conditions on the lunar surface and in
interplanetary space to cast a decisive a priori ju@gment against the hypothesis,

In conclusion, we feel that general stress on minimizing contamination of any kind
and excluding microorganisms as far as pkauakaky pechnical,feasible are plausible
parts of any cautious program of investigation. Rather thdn leave the moon for
the uncontrolled depesit of uncontrolled contamination, it should be the testing
ground for the same cautions as apply to the more sensitive planets.
Westex-|

The following scientists participated in the first meeting at Stanford on

planetary biology. Fra 4 4959

Institution Name Position
University of Roger Stanier Professor of Bacteriology
California Gunther Stent Assoc. Professor of Bacteriology and Virology
(Berkeley) Melvin Calvin Professot of Chemistry
Dan Mazia Professor of Zoology

Harold F, Weaver Professor of Astronomy

(Davis) Alan G. Marr Assoc. Professor of Microbiology
Stanford
University Konrad B. Krauskopf Professor of Geochemistry

Joshua Lederberg Professor of Genetics; Professor of Biology

C.B. Ban Niel Herzstein Professor of Biology
University of Aaron Novick Director and Professor of Biophysics
Oregon
California Insti- Norman
tute of Technology Horowitz Professor of Biology

Stanford Research

Institute Fred Kamphoefner Director, Control Systems Laboratory
JPL-NASA A. Hibbs
R. Davies