Redox stratification of an ancient lake in Gale crater, Mars

The primary goal of NASA’s Curiosity rover mission is to explore and quantitatively assess a local region on Mars’ surface as a potential habitat for past or present life. A necessary component of that assessment involves an investigation of the surface chemical conditions and paleoclimate of ancient Mars. Gale crater was selected as the landing site for Curiosity; it hosts a ~5-km-tall mountain of layered sedimentary rock. The rocks of Mount Sharp preserve a long-duration record of martian environmental conditions. Geological reconstructions from Curiosity rover data have revealed an ancient, habitable lake environment that was sustained for tens of thousands to tens of millions of years by rivers draining into the crater.