In a paper published in Nature Geoscience, researchers report they've found "perchlorates" in readings taken from Mars Curisosity. Perchlorates are a kind of hydrated salt that seriously implies that there was flowing water recently present. The perchlorates were found on canyons and crater walls during the warm seasons, and the faded when conditions became cooler. Scientists aren't sure where the water is coming from, with some possibilities being underground ice or aquifers.
“There is liquid water today on the surface of Mars,” The lead scientist on Nasa’s Mars exploration program told the Guardian. “Because of this, we suspect that it is at least possible to have a habitable environment today.” If we do send men to Mars, we should target these areas with potential running water.