From Ed Prior
Amid calls to relax the need for spacecraft sterilisation as we seek evidence of life beyond Earth (6 July, p 8), it’s worth recalling how such efforts have fared in the past.
I worked at NASA’s Langley Research Center in the 1970s, and I remember the concern that many involved in the two Viking missions to Mars had about heating sensitive components to kill microbes. In the end, Viking was a remarkable success, but worries about the impact of the sterilisation process on spacecraft instrumentation remain.
Earlier in the same decade, the Soviet Union’s Mars 2 and Mars 3 spacecraft both made it to the surface of Mars – in 1971, followed by Mars 6 in 1973. However, questions have been raised about whether their .
The good news is that the intense UV radiation encountered on Mars and strong oxidants on the surface probably killed any microbes from Earth that a Soviet – or US – mission might have deposited.
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If life is found on Mars, the next big question should be: is it based on parasitism? I believe life on Earth is, which is why . Is parasitism a universal property of life or is it confined to Earth? Letting our microbes contaminate other planets may eradicate native species if they have no defence against parasites.
Poquoson, Virginia, US
