Methane on Mars may be produced at rates 3000 times higher than previously thought and partially destroyed by dust storms, controversial new research suggests. The work is sure to reignite the debate over a possible biological origin for the gas, but another team reports that subsurface volcanism alone - and not life - can account for the gas.Sunlight is thought to destroy methane molecules in Mars's atmosphere over about 300 years. So recent discoveries of the gas by space- and ground-based instruments suggested it is actively being replenished by geological processes or – possibly – living microbes. The mystery deepened when some researchers claimed to find methane concentrated in certain locations on Mars. That is a puzzle because atmospheric currents are expected to spread the gas evenly around the planet in a matter of weeks or months.Now, a team led by Michael Mumma of NASA's Goddard Space Flight Center in Greenbelt, Maryland, US, reports further evidence of the phenomenon. Using an infrared telescope in Hawaii and the Gemini South telescope in Chile, the group found concentrations of methane ranging from zero to more than 250 parts per billion across Mars. Such a drastic difference suggests something must be destroying the methane before it can be mixed uniformly through the atmosphere, says Mumma. And if it is destroyed in one month, he says, that implies it must be replenished 3000 times faster than current estimates suggest.
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