STANFORD UNIVERSITY SCHOOL OF MEDICINE
STANFORD MEDICAL CENTER
PALG -AL-FO,-GALIFORNIA--94304
Stanford, California 94305

DEPARTMENT OF GENETICS Area Code 415

Instrumentation Research Laboratories 321-1200
Elliott C. Levinthal, Director

June 9, 1969

Dr. Thomas 0. Paine

Administrator

National Aeronautics and Space Administration
Washington, D. C. 20546

Dear Dr. Paine:

The issue of back-contamination of the earth by a lunar return
sample was discussed at the last meeting of OSSA's Planetary Biology
Subcommittee, of which I am a member. I would like to take this
occasion to clarify my position on this matter.

In my view the design of a system to control lunar back-contamination

has an important purpose. It tests a system against the lowest risk
return sample mission and provides some degree of protection for this type
mission. Since the possible losses are so large a significant effort

is worthwhile even though the risks are admittedly very low. What was
being criticized at our subcommittee meeting was the failure to make
incremental efforts that would achieve a large increase in system
reliability.

The investment in this system has been clearly worth the cost provided

we extract everything of value that can be learned from this experience.
There is no other way in which we could have come to appreciate the

real difficulties in creating a system capable of managing back-contamination
for missions of higher risk such as Mars. The most important fact that

has been demonstrated is that protocols for protection against back-
contamination depend, for their effectiveness, on a significant, widespread,
and well-founded belief in the risks involved. This puts a requirement

on thorough biological reconnaissance and in situ analysis before

planning return sample or manned planetary missions that may have a

higher a priori risk than the lunar missions. These views are given

more completely in the enclosed paper (particularly the conclusions)

given at the 1967 London COSPAR meeting.

Very truly yours,

Elliott Levinthal
ECL/mla

bee: R. Young -
J. Lederberg “