Canned Voyager

If any evidence of life is eventually found on the moon, it may well be because earthly microorganisms hitched rides on the Russian and U.S. spacecraft that have crashed on the lunar surface. To avoid similar celestial contamination that might obscure or alternative life forms before they are identified and studied, both U.S. and Soviet scientists plan to give future unmanned planetary probes a thorough cleansing before they leave the earth. At a conference on spacecraft sterilization sponsored by NASA at Caltech's Jet Propulsion Laboratory, scientists explained how the chances of contaminating Mars will be reduced to less than 1 in 10,000 when the Voyager spacecraft makes a soft Martian landing in 1971.

No Bugs. To rid Voyager of its terrestrial bugs, contractors will be required to build spacecraft parts in "clean" rooms like those where many delicate instruments are now produced. Final assembly will take place in an ultraclean room, where living contamination will be reduced to as little as a thousandth of what is allowed in clean rooms. At the same time, all of Voyager's exposed surfaces will be decontaminated with ethylene oxide, a colorless gas that is deadly to microorganisms. Finally, the spacecraft will be placed in an airtight, teacup-shaped canister and baked in a giant oven for as long as 53 hours at a temperature of 257DEG F.--enough heat exposure to kill even the organisms that live within the solid metals and other materials used in spacecraft construction.

While prolonged heating is the most effective way of killing any microorganisms that survive other sterilization processes, it can also damage sensitive instruments and controls. Scientists now believe that equipment aboard the unsuccessful Ranger 4 and 5 moon shots may have deteriorated during heat-sterilization attempts. In an effort to eliminate the possibility of similar damage to Voyager, NASA will insist that all of its equipment be built to withstand high-sterilization temperatures--which will call for costly and time-consuming redesigning of many instruments.

No Chances. Despite the inconvenience and expense--and the ever-present danger that Voyager's reliability might be impaired--NASA has no doubts about the ultimate value of its spacecraft-sterilization program. Says Associate Administrator Homer E. Newell: "Successful biological exploration of the planets is a goal that supersedes in importance any program, flight or schedule that would endanger the eventual acquisition of knowledge of extraterrestrial life."

Having effectively sterilized Voyager, scientists will take no chances on the spacecraft's becoming recontaminated by stray microorganisms as it rockets upward through the earth's atmosphere. The spacecraft will still be in its sealed canister when it is mounted on its launching rocket and blasted aloft. Only when it reaches deep into sterile space will explosive bolts be fired to release the life-free Voyager from its protective envelope and allow it to proceed toward its rendezvous with Mars.

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