NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

2H OE KES:

March 11, 1960

‘TELEPHONE: EXECUTIVE 3-3260

TWX: WA 755
IN REPLY REFER TO:
Theoretical Division
Goddard Space Flight Center
8719 Colesville Road
Silver Spring, Maryland

Prof. Joshua Lederberg
Department of Physics
Stanford University
Stanford, California

Dear Dr. Lederberg:

In conjunction with the ideas which you have expressed
that there may be life on the moon or in space or on other
planets, it occurred to me that there might be several bio-
logical experiments which could be tried at this time and
which would help to delimit the possibilities.

In the first place, would it be possible to determine
whether a spore could survive a fall onto the lunar surface?
The terminal velocity is approximately 9,000 feet per second,
which can be reached by light gas guns. Would it be possible
to fire pellets of various sizes containing bacteria and then
test whether any of them survive the impact? A priori, one
would think that on a large pellet some portions might survive
the impact; but that as the pellet was reduced in size a limit
would be reached below which no life would survive. Such a
demonstration would eliminate the possibility of life reaching
the moon through space.

In the second place, it might be possible to expose Petri
dishes at high altitudes in airplanes to determine whether
there are any bacteria riding on the micrometeorites. This
experiment might be useful in distinguishing between the true
micrometeorites, which should contain non-terrestrial forms
of life if any, and dust contaminations which might carry
terrestrial forms of life. (At the present time, it is very
difficult to think of any way of discriminating between micro-
meteorites and terrestrial particles.)

In the third place, if it were possible to secure the
Igast object it might be worthwhile to examine it. I believe
the Igast object to be a portion of the moon's crust which has
not been remelted in flight. It is imaginable that if life or
organic substances exist on the moon they would have been brought
to us by this object. The likelihood is similar to that for
any other body brought back from the moon.

Do you have any information about the sterilization techniques
used by the Russians? I am told that the problem of steriliza-
tion is so difficult that their precautions would have had to be
quite extensive.

Sincerely yours,

gob. A Cy [ee Le
John A. O'Keefe

Assistant Chief,
Theoretical Division

JAO:sbb