This enhanced-color HiRISE image shows a one kilometer segment of the wall and rim of a roughly 4 kilometer wide (2.5 mile) impact crater on Mars. Teh dark area at the top of the image is the surface outside the crater; the lower part of the image is the interior crater wall showing lighter, multi-colored layered bedrock. Craters are like windows that peer into the subsurface of Mars. (Photo: NASA/JPL/University of Arizona)