The Sample Analysis at Mars (SAM) instrument onboard NASA’s Curiosity rover has measured the seasonal changes in the gases that fill the air directly above the surface of Gale Crater, and noticed something baffling: oxygen behaves in a way that so far planetary scientists cannot explain through any known atmospheric or surface process. Curiosity rover took this selfie on October 11, 2019. The rover drilled twice in this location, nicknamed Glen...
