In DepthPlanetary Science

Mars methane rises and falls with the seasons

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Science  05 Jan 2018:
Vol. 359, Issue 6371, pp. 16-17
DOI: 10.1126/science.359.6371.16

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On Earth, atmospheric methane is a prominent sign of life. On Mars, the story is more complicated. Trace detections of methane, alongside glimpses of larger spikes, have fueled debates about biological and nonbiological sources of the gas. Now, NASA scientists have announced a new twist in the tale: Methane regularly rises to a peak in late northern summer in a seasonal pattern. The swings are larger than can be explained by the planet's seasonal freeze-thaw cycles. The wiggles are a mystery within a larger mystery: claims of methane spikes an order of magnitude or two higher than the background. Some scientists say meteor showers could be responsible, by depositing carbonaceous material in the atmosphere that reacts to form methane. A close encounter on 24 January with debris from a comet could provide a chance to test the hypothesis.

  • * With additional reporting by Paul Voosen from the AGUmeeting.

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