|Image credit (original on right, obviously): NASA / ESA / Hubble Heritage Team (STScI/AURA)|
Did water once flow on the surface of another planet in the solar system? Although Mars is now a desert, we have growing evidence that rain and flash floods once scoured the surface, sustaining a network of streams and lakes—and perhaps even an ocean. Today it appears that some of this water is locked up in subsurface permafrost and the rest has escaped into space.To read the rest, click on "Mars—The Other Blue Planet?"
Where did all this liquid water come from, and why did it disappear? These are two of the greatest mysteries in planetary astronomy. Mars is currently too cold and its atmosphere is too thin to support liquid water. So how did it ever produce and sustain an ocean and a thick atmosphere?
The spacecraft and rovers sent to Mars over the past five years are equipped with next-generation instruments to help solve these very questions. Yet despite our ever-increasing knowledge of the Red Planet, investigators are still baffled.
There is some disagreement about whether or not Mars had, and still has, actual water. There is quite a bit of evidence, which also raises many questions.