NASA's Mars Reconnaissance Orbiter (MRO) has found evidence that McLaughlin Crater once contained a lake fed by flowing groundwater.
Clay minerals - rocks that usually form when water is present for long periods of time - cover much more of Mars than previously thought, say Georgia Institute of Technology scientists.
One of the most encouraging signs for those searching for evidence of early water on Mars has been the existence of clays. But a French-US team has now rained on that particular parade.
Living bacteria have been discovered deep beneath the ocean where they've had no new food or oxygen since dinosaurs roamed the earth.
Liquid water on the Martian surface was probably never around for very long, meaning life would have struggled to gain a foothold there.