Odyssey Views A Surface Changed by Floods:
Channels scoured by ancient outbursts of flood waters are seen in this orbital view from Odyssey's Thermal Emission Imaging System.The channels are billions of years old and have likely been affected by multiple processes over time. Here, two channels, Tiu Vallis on the left and Ares Vallis on the right, flow northward from the highlands of the southern hemisphere of Mars.
The stark difference between today's cold, dry Mars and the evidence of flood waters in the past tells scientists that the Martian climate has seen great changes. Unraveling the workings of that climate history is one of the major challenges in Mars science.