dane 11, 1958

Dr, PF, C, Trexler
Loband Institute
University of Notre Dame
Notre Deme, Indiam

Year Dr, Trexlert

Thank you very mach fost your letter of June 9, There should
be much careful and critical discussion of these problems.

I would not really be terribly alarmed about the level of
contamination that would be introduced by e clean (not necessarily
sterilized) spacecraft mechanian, I would be much more concerned
about the contamimtion that would accompany ill-conceived blologi-
eal experiment, e.g. the hard landing of a Large mammal, or @ pre~
mature manned expedition, One difficulty is that s bard landing
might disperse the contents of a missile over very nearly the entire
surface of the moon (witness the "rays" which emanate fron the
meteoritic craters), In any case, why should there be any hard
landing without well-thought out scientific objectives?

This discussion of the moon is a preliminary to the exploration

of the planets, and for Mars ani Venus I feel’ there should be extra

ordimry care net te introduce even mininal contamination until the
biological possibilities have been carefully thought out.

Tours sincerely,

Joshua Lederberg
Profeseor of Medical Cem tics

Jt/eu
coolr, Porter

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