A 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. [Watch: Mars Weather Report by NASA's Curiosity Rover]
"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."
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