The remnants of a vast sheet of ice lies hidden under Martian rubble, revealed by a new and wonderfully detailed radar map of Mars’ mid-latitudes. “The icy leftovers have been found over a significant part of Deuteronilus Mensae, an area about halfway between the Martian equator and North Pole. The ice was mapped by the Italian Space Agency's Shallow Radar instrument on NASA's Mars Reconnaissance Orbiter. ‘It's definitely a record of a different climate period,’ says Dr Jeffrey Plaut of NASA's Jet Propulsion Laboratory. Today all that remains are thick ice piles buried at the foot of hillsides under rocky debris. ‘The debris protects them from subliming,’ says Plaut, referring to the process of solid water ice evaporating into the air without any intervening liquid phase. Plaut and his colleagues prepared their new ice map for presentation at this week's Lunar and Planetary Science Conference.”