ESA's Mars Express has returned strong evidence for an ocean once covering part of Mars. Using radar, it has detected sediments reminiscent of an ocean floor within the boundaries of previously identified, ancient shorelines on Mars.

Mars may have been arid for more than 600 million years, making it too hostile for any life to survive on the planet’s surface, according to researchers who have been carrying out the painstaking task of analysing individual particles of Martian soil. Dr Tom Pike, from Imperial College London, will discuss the team’s analysis at an ESA meeting on 7 February 2012.

This image from the HiRISE camera on the MRO probe shows wind-shaped sand-dunes

The Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument on board Mars Express has recently completed a subsurface sounding campaign over the planet's North Pole, to map its ice-content and seasonal changes