Cerberus Fossae fissures, Mars. Coloured satellite image of ground fissures known as the Cerberus Fossae. These were formed when pressure from underground magma pulled the crust apart along fault lines. The process released large amounts of pressurised underground water and volcanic lava. The dark blue areas are basaltic rock and the lighter-coloured rippled surface is wind-blown sand. Image obtained by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter (MRO) on 23rd January 2008. The width of this image is roughly 900 metres across.