Mars Methane Found, Raising Possibility of Life

Jan. 15, 2008 -- Scientists have discovered rich plumes of methane on Mars that not only disappear quickly, but are replenished by unknown sources that could be biological or geochemical in origin.

"Either way, it's very interesting," planetary scientist Michael Mumma, with NASA's Goddard Space Flight Center in Greenbelt, Md., told Discovery News. "Mars is not a dead planet."

Mumma and colleagues used infrared spectrometers on three ground-based telescopes to monitor concentrations of methane in Mars' atmosphere over time and made a rather startling discovery: Not only does the planet have methane-rich plumes over several discrete sites, it also has an as-yet undetermined method for replenishing the methane that puts Earthly processes to shame.

On Earth, most of the methane in the atmosphere comes from cows' digestive processes and bacteria in wetlands and landfills. It also is produced by geo-thermal processes, such as volcanic eruptions and decaying coal.

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The gas is broken down over time by ultraviolet light from the sun.

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On Mars, "it's clear that there is a mechanism at work that is more efficient than photochemistry -- on the order of 100 times more efficient," Mumma said.

Whatever the source, methane on Mars should stick around for about 300 years, all things being equal. Instead, Mumma and his team, who published their findings in this week's issue of Science, found that over parts of Mars the methane is disappearing in a span of time as short as one year.

"We really can't tell if it's biological or geochemical at this time," Mumma added. "On Earth, it can be produced by either mechanism."

The definitive way to determine the methane's origins is to analyze its isotopes. Methane produced from biological sources on Earth has distinctively different isotopic ratios than methane generated by geochemical processes.