SAN FRANCISCO, CALIFORNIA—New data from the Curiosity rover exploring Mars (seen above) demonstrate that not only is methane present on Mars, but the planet may also be periodically belching it out. In 2009, NASA researchers claimed to observe Mars spurting out plumes of the gas, hinting at the possibility of life forms actively chugging it out. But contradictory findings later left researchers dubious of the presence of martian methane at all. Now, according to data published online today in Science and presented here at a meeting of the American Geophysical Union, the gas is present in the martian atmosphere at concentrations of roughly 0.7 parts per billion—about 4000 times less than in Earth’s atmosphere. The determination arose from nearly 2 months of air chemistry analyses on board the rover, during which time it also observed dramatic spikes in methane concentrations. At their highest, the bursts contained about 10 times more methane than the background in the atmosphere. Methane is a known byproduct of microbial life, but it can also arise when water alters minerals below the surface or by escaping from gas-trapping ice cages called clathrates. Researchers caution that more research is necessary to determine the gas’s precise origins. As Curiosity carries on, researchers plan to analyze soil and sediment samples for organic material and to team up with Mars orbiters to search for methane patterns in the atmosphere.
*Correction, 17 December, 12:07 p.m.: This item originally contained a picture of the Opportunity rover. We have swapped it with a picture of the Curiosity rover.