Posted by tourdemars to Mars Express at July 28, 2005 10:50 PM

These images, taken by the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express spacecraft, show a patch of water ice sitting on the floor of an unnamed crater near the Martian north pole. The crater is 35 kilometres wide and has a maximum depth of approximately 2 kilometres beneath the crater rim. The circular patch of bright material located at the centre of the crater is residual water ice. This white patch is present all year round, as the temperature and pressure are not high enough to allow sublimation of water ice.