Methane gas was detected on Mars 6 years ago. Scientists might finally know why.

Almost six years after NASA's Curiosity rover first detected hints of methane on Mars, scientists may have uncovered the reason it was there. On June 16, 2013, the Curiosity rover's sensors picked up a spike of methane gas levels in the Gale Crater, the 96-mile crater where it had landed in 2012, The Guardian explained. This reading immediately raised some questions, since methane is a gas often produced by microbial life forms on Earth (although it can be released in other ways). Since then, ma...