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More (from this Economist article)
Although NASA's researchers may not have discovered life on Mars, they have produced some interesting work that supports a biological explanation for the origin of the methane. Later this month Carol Stoker, of the agency's Ames Research Centre in California, and her colleagues, will tell the Lunar and Planetary Science conference in League City, Texas, that they have the first report of a subsurface ecosystem that can use sulphide minerals as an energy source.
Dr Stoker has been exploring a place on Earth that looks geochemically similar to an area of Mars called Sinus Meridiani. The place in question is near the source of the Rio Tinto, in Spain, and the similarity is the presence of a mineral called jarosite. The team drilled beneath the ground to take sample cores from up to 165 metres beneath the surface. There, they found a microbial ecosystem that appeared to be producing jarosite (a sulphate-based mineral) by oxidising rocks made of iron sulphide. One by-product of this process is methane, whose carbon comes from atmospheric carbon dioxide. And Mars, too, has carbon dioxide in its atmosphere. It has yet to be established whether points of methane concentration in the Martian atmosphere coincide with jarosite deposits. If they do, though, the case for life on Mars will look a lot stronger than it does at the moment. |
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