No one has looked for life on Mars for more than 30 years, ever since NASA's Viking missions sent back inconclusive results. Genomics maverick Craig Venter wants to change that. Cracker of the human genome and builder of synthetic life, Venter announced at the Wired Health Conference in New York last week that he wants to send a DNA sequencer to Mars and beam back the genomes of any alien microbes.
Details of this ambitious plan are slim, and Venter has declined to elaborate. But there is reason to think Mars DNA can be found – if we know how and where to look.
Previous hunts for life, including the experiments on the Viking landers, looked for organic molecules on Mars's surface. The results have been plagued by ambiguity, especially in the light of growing evidence that organic molecules can be formed by natural processes that do not involve life.
Finding DNA would be a much more direct indicator of life, and there is a chance it is out there. The precursors to ribose – the sugar found in DNA and RNA – have been detected in interstellar space, and complex organic molecules have been found on Saturn's moons Titan and Enceladus. Life's raw materials could have spread throughout the early solar system, and life may have emerged several times from a common set of ingredients.
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