New submitter universe520 writes: Using neat imaging technology that allows them to determine the chemical compound of a substance by looking at the light reflected from it, scientists have spotted the traces of flowing water on Mars. By looking at the dark streaks on some photos of Mars, Lujendra Ojha from Georgia Tech has found compounds that are made in liquid water—meaning that water may be trickling down those streaks when the climate is just right. From the linked Economist piece: Details remain to be worked out, including where the water in question originates. Possibly, it derives from subsurface ice. Or it might condense out of Mars’s thin, dry atmosphere. Wherever it does come from, though, the amounts in question are modest in the extreme. But even modest amounts of water are intriguing to biologists. If Martians evolved during their planet’s earlier, wetter phase, the continued presence of water means it is just about possible that a few especially hardy types have survived until the present day—clinging on in dwindling pockets of dampness in the way that some “extremophile” bacteria on Earth are able to live in cold, salty and arid environments.