Big methane spike that NASA’s Mars rover Curiosity detected two years ago was not due to seasonal changes on the Red Planet, NASA scientists said.

For a few weeks in late 2013 and early 2014, Curiosity noticed that atmospheric methane — a gas that could possibly be an indication of microbial activity — surged from an average background level of about 0.7 parts per billion all the way up to 7 parts per billion.

That increase occurred during the rover’s first Martian autumn. But the methane spike did not recur in the second Red Planet autumn, NASA officials said.
“It was an episodic release, still unexplained,” NASA officials said of the methane surge. “However, the rover’s measurements do suggest that much subtler changes in the background methane concentration — amounts much less than during the spike — may follow a seasonal pattern.”

This diagram shows possible ways that methane might make it into Mars' atmosphere (sources) and disappear from the atmosphere (sinks). Credit: NASA/JPL-Caltech/SAM-GSFC/Univ. of Michigan
This diagram shows possible ways that methane might make it into Mars’ atmosphere (sources) and disappear from the atmosphere (sinks). Credit: NASA/JPL-Caltech/SAM-GSFC/Univ. of Michigan

This broader background pattern, if it is confirmed, could be related to seasonal changes in pressure or ultraviolet radiation, the officials added. (Methane can be produced by geological as well as biological processes, so its presence is not solid evidence of Martian life.)

Source: Space.com