Mars’ ancient atmosphere may not have had much oxygen after all

There may have been no oxygen in the atmosphere of ancient Mars after all, a new study has found — but don’t despair, there still could have been living creatures crawling on the planet’s surface.

When NASA’s Curiosity rover found manganese oxide in Martian rocks in 2016, many planetary scientists rejoiced, believing that the mineral’s presence was a significant hint of past concentrations of oxygen in the planet’s atmosphere. The odds of past existence of life on Mars suddenly seemed higher, too, as oxygen is one of the key enablers of life on Earth.