A Watery Mars

Two recent studies argue water has a clear role in Mars' past, present, and future.

One finds that flowing water carved out many of the surface features we see on Mars today, including the vast Valles Marineris (roughly, Mariner Valley), a canyon system that stretches 2,500 miles across the planet. Flowing water capable of creating such geologic formations, of course, suggests huge amounts of water existed on the surface of Mars for extended periods. Though the study points out that the carving of surface features such as Marineris could conceivably have occurred quickly, over decades, many scientists believe Mars once had an ocean that covered perhaps one third of the surface. On present-day Earth, oceans cover roughly two thirds of the surface.

Another study has found water ice in the south polar ice cap. Astronomers thought for decades the Martian polar caps were carbon dioxide, or dry, ice. That's basically accurate, but a few years ago traces of water ice were found in the northern cap. Now, a study by Adrian Brown of the SETI Institute (yes, they do more than listen for alien radio signals) finds traces of water ice in the southern polar cap.

Both studies support the possibility of a substantial amount of subsurface water on Mars today. That, in turn, would be good news for both the possible human exploration and colonization of the planet, as well as for the possibility that native Martian life still wiggles.