Astronomy
The Potential for Methanogenic Life in Mars' Subsurface
Quick fact
Methane has been repeatedly detected in Mars' atmosphere, but in puzzlingly variable amounts—and at least some of it could be produced by microbes living deep underground. However, the most famous detection by the Curiosity rover was later found to be likely contaminated by Earthly methane from the rover itself.
Why this is interesting
When you think of life on Mars, you might picture little green men—but what if the real clue is a simple gas that you cook with on Earth? Why would that gas make astrobiologists rethink everything?