Does water flow on the surface of Mars ?

Dark streaks on photographs taken from orbit could be indicators that water does flow on the Red Planet.

Despite freezing temperatures and a landscape that seems for all intents and purposes to be as dry as a bone, scientists believe that there are still hints that liquid water is able to flow, albeit rarely, on the surface of Mars.

The most tantalizing evidence of this has come in the form of photographs taken by NASA's Mars Reconnaissance Orbiter which show strange dark streaks that seem to grow and shrink in time with the seasons. It is believed that these streaks could be patches where water has seeped on to the surface during warmer periods.

"The subsurface is probably the best place to find present-day life if it exists at all because it is protected from the radiation and temperature extremes," said planetary scientist Alfred McEwen. "Maybe some of that water occasionally leaks out onto the surface, where we could see evidence for that subsurface life."