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. Taken during revolution 11497 and centred at around 3°S and 109°E, the image has a ground resolution of about 22 m per pixel. The valley’s U-shaped cross section is indicative of a process called groundwater sapping, whereby volcanic heat has melted subsurface 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 100 km-wide crater.