In DepthPlanetary Science

Fear of microbial taint curbs Mars explorers

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Science  11 Aug 2017:
Vol. 357, Issue 6351, pp. 535-536
DOI: 10.1126/science.357.6351.535

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  • RE: Relaxing planetary protection could be fatal to future life-seeking missions

    Relaxing planetary protection could be fatal to future life-seeking missions

    The 11 August article, "Fear of microbial taint curbs Mars explorers" (Paul Voosen), comments on NASA's consideration of reducing planetary protection standards for missions to Mars, allowing restrictions placed on the rover Curiosity's freedom to roam into "special regions" of the planet to be relaxed. Such a decision is short-sighted and counter-productive for at least two reasons. First, as reported in the article, Alberto Fairén, a planetary scientist at Cornell University, supports the relaxation regardless of its potential contamination of Mars with Earth organisms. He cites that even if some contaminating organisms do survive, "future missions could distinguish between earthly and martian microbes by sequencing their genomes." That may hold true if you had the alien organism's DNA to sequence. However, much of the ongoing search for potential extraterrestrial life is directed at seeking the signs of life, not the organism itself. For example, NASA's two Viking missions in the late 1970s sought chemical signatures associated with biological activity, such as gasses produced by metabolism, not the discrete organisms themselves. Contamination with Earth organisms may produce similar signatures, confounding future searches. Second, Jim Kasting, a geoscientist at Pennsylvania State University, said that martian soil has proved to...

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    Competing Interests: None declared.