NASA The amount of methane in the Martian atmosphere changes with the seasons, and no one knows why. Hints of a methane anomaly were first noticed by the Mariner missions in the 1970s, and confirmed by the Curiosity rover in 2013. Methane is highly reactive so some chemical process must make it anew each time. It could, the astrophysicist Paul Sutter wrote on Universe Today, be something inorganic, such as water oxidizing certain rocks, but that would mean there is liquid water flowing underground. The exciting prospect, of course, is life: Many Earth microbes produce methane, although it would still imply liquid water. “The only way to answer this is to keep sending missions back to Mars,” said Sutter, “and start digging.” |