Although the surface of Mars is presently cold and dry, plenty of evidence suggests that the red planet was once partly covered with water. Researchers have theorized that life might have evolved on Mars when it was wet, and life could even be there now, hidden in subterranean aquifers.

“On Earth, water means life,” said Alberto Fairen, an astrobiologist at the Center of Astrobiology in Spain and Cornell University in Ithaca, New York. “The surface of Mars today is extremely dry, but there are lots of clues pointing to a much wetter past. Evidence for past water may be the clue to follow to find extinct life on Mars and if some of that water still persists on Mars today, then for sure the prospects to find extant life go up.”

Water on Mars also has important implications for research areas at NASA beyond the work of the NASA Astrobiology Program. Even if life no longer lives on Mars, or never existed in the first place, water could still prove vital to future life on Mars in the form of human colonies on the red planet. Water is useful not only for drinking, but also to shield against radiation, and as fuel when it is split into hydrogen and oxygen. The prospects of past, present and future life on Mars means that much research at NASA concerning the red planet concentrates on its water.