NASA has tried looking for signs of life on Mars precisely once, in the 1976 Viking mission. The result was positive. The reason nobody says there is life on Mars is that another experiment, part of the same mission, couldn’t find any carbon-based “organic” chemicals in Martian soil. This, NASA decided, overruled the other result: with no carbon present, there could be no microbes living on or under the surface of Mars.Last year, the Phoenix lander repeated the carbon search and failed to find organic molecules. The problem is, we know that there ought to be organic molecules on Mars. Asteroid and comet impacts will have put them there. So what’s going on?
Both of the searches for organic molecules, it turns out, have been deeply flawed. In 2000, the chief engineer on the 1976 experiment finally admitted that his experiment was simply not sensitive enough to overrule anything. Put bluntly, it didn’t work properly – and it never had, even during testing on Earth.
Now a handful of brave NASA scientists have exposed a problem with the latest attempt to pronounce that Mars was dead.
The best argument for why no one has even found carbon brought in on asteroids and comets is that chemicals called perchlorates, also thought to be in the Martian soil, have destroyed it all. When perchlorates get hot, they burn up carbon-based molecules. That’s why NASA uses them in rocket fuel.
The problem is, as NASA's Douglas Ming (the Merciless) has pointed out in a recent paper, the experiments to search for carbon involve heating soil samples to a few hundred degrees and sniffing the vapours. If the soil contains carbon molecules and perchlorates, the carbon molecules will simply burn up. No wonder they couldn’t find any.
Gilbert Levin, who ran the 1976 experiment to search for life, the one that got a positive result, thinks it’s all down to a religious conspiracy dating back to the early 1960s. When I was researching my book 13 Things That Don’t Make Sense, I travelled to Levin’s Maryland offices and listened to his account of the run-up to Viking. In 1961, he told me, the Executive Director of the American Institute of Biological Sciences, invited him to attend a meeting in Washington. When Levin arrived, he found himself among fifteen of the top scientific minds in the US. None of them knew what the meeting was about until John Olive told them he had been charged by NASA with directing an effort to look for life on other planets.
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