Orbiter and rover data are showing that water may have flowed more recently on the Martian surface, maybe even into the present era.

This mosaic of images from the camera on the Curiosity rover shows a series of sedimentary deposits in Gale Crater. NASA / JPL-Caltech / MSSS

An overview of evidence gathered over the last several years by Mars orbiters and landers, presented at the recent meeting of the American Astronomical Society’s Division for Planetary Sciences (DPS), is leading scientists to reassess the planet’s past climate.

Whereas the going theory had Mars mostly cold and dry for at least the last 3 billion years, recent data suggests otherwise. Images and analysis of layered deposits of ice, well-dated signs of recently flowing water, and other evidence point to sporadic but repeated epochs of a warmth, with liquid water on the surface.…