Wet Mars... Again

Two recent studies of images taken of the surface of Mars by orbiting spacecraft suggest the planet once had substantial water, or water ice, on the surface.

One study sees evidence of a glacier in the equatorial regions of Mars in the relatively recent past-- within the latest 100 million years. Scientists calculate the glacier would've been about a mile thick. Today, of course, the only ice on the surface is at the poles. This evidence suggests Mars' climate oscillates between wet and dry epochs. We happen to be seeing the planet during a dry period.

Another study suggests hydrothermal springs once existed on Mars. Not only would that put water on the surface, but a warm, watery springs, scientists believe, would be a place life might thrive.

Other studies, however, also based on images from orbit, have suggested Mars has been, at least for the past couple billion years, essentially a dry world. Volcanically active, perhaps, but a world where water played a minor role. Barring cooperation from Mars, the only way to finally nail down Mars' climate history would seem to be putting extremely advanced scientific instruments on the surface over a period of several years and doing the hard work of gathering and analyzing physical evidence.