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From: lmc@denelcor.UUCP (Lyle McElhaney)
Newsgroups: net.space
Subject: Re: Sterilization of space craft
Message-ID: <453@denelcor.UUCP>
Date: Sat, 2-Jun-84 18:03:47 EDT
Article-I.D.: denelcor.453
Posted: Sat Jun  2 18:03:47 1984
Date-Received: Tue, 5-Jun-84 08:34:30 EDT
References: <275@ames-lm.UUCP>
Organization: Denelcor, Aurora, CO
Lines: 25

Concerning sterilization of the Viking landers:

Each lander was constructed in class 100,000 clean room conditions.  After
completion, they were encased in a bioshell through which only electrical
connectors and piping for loading propellants pierced.  The entire lander
with shell was then baked at 450 degrees F for 40 hours, enough to ensure
that the 450 degree temperature had permeated the entire structure of the
lander (including all the electronics, the pyrotecnic assemblies, the
batteries, and so on).  After liftoff, above the atmosphere, the bioshell
was jettisoned.  While in Martian orbit, the lander was specially oriented
toward the sun for sufficient time that the entire exposed surface received
sufficient UV to kill any bacteria on the lander surface.  This
"Sterilization Plan" was performed in accordance with NASA contractual
requirements, in turn derived from a space treaty (I think under UN
auspices) that specifies a fifty year moratorium on pollution of Mars by
terrestrial fauna, not to speak of allowing the biology experiment to find
bonafide Martian life.

I can remember debates over whether the precautions were sufficient to keep
bacteria encapsulated within the cast body of the lander itself from
leaking out before the fifty year limit had expired. it was, all in all, an
extremely interesting project to work on.
-- 
		Lyle McElhaney
		(hao,brl-bmd,nbires,csu-cs,scgvaxd)!denelcor!lmc