eugene@ames-lm.UUCP (Eugene Miya) (05/29/84)
The Viking Landers which went to Mars were adequately sterilized. The Galileo probe will probably also be adequately sterilized, too. The environmental chambers where is this are located at JPL. The probes to Venus (pioneer) were also probably cleaned, too. This has to be done because like the case of Viking, instrumentation could be affected by non sterile equipment. Carl Sagan and others (in the early days of the lunar program) pointed out the need to avoid contamination of the worlds we visit in a series of papers which I don't have the references to. There are limits to the (and tests of these limits) procedures used, however, and probably some sci fi writer would make some interesting fiction based on a Star Trek II Genesis idea (modern bacteria is pretty sophisticated compared to early life forms). --eugene miya NASA Ames Res. Ctr. [Disclaimer: The above views do not state official policy or opinion of NASA and are those of the author.]
lmc@denelcor.UUCP (Lyle McElhaney) (06/03/84)
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