Stone Cold Mars

Last year, I reported about a possibility of microbes on Mars because of a large amount of methane. Another possibility has come up -- dare I say more parsimonious?

In today's Nature:

When methane was found in Mars's atmosphere last year, the media (and many scientists) seized on the idea that it was a whiff of life from martian bacteria. As estimates of the gas grew, so did column inches on the hopes of finding microbes.

But the real source may be far more mundane: chemistry. Geologists have calculated that given a supply of water and carbonates, just 80,000 tonnes of the mineral olivine would be enough to generate a year's worth of methane. Another paper reports a Cuba-sized olivine field on Mars's surface, and suggests there may be more beneath. Could the prospects for life be stone dead?