This computer-generated perspective view of a network of short valleys feeding Palos Crater was created using data from the High-Resolution Stereo Camera on ESA’s Mars Express. The valley’s U-shaped cross section is indicative of a process called groundwater sapping, whereby volcanic heat has melted sub-surface ice, liberating water to the surface and causing the ground around it to collapse. The top left of the image is the periphery of a 60-mile-wide (100km) crater. // ESA/DLR/FU Berlin (G. Neukum)