Further indication has been received about the existence of water on Mars, intensifying expectations of the possibility of finding life on the planet. The High Resolution Stereo Camera (hrsc) on board Mars Express, the European Space Agency (esa) probe exploring the planet, shows a giant patch of water ice nestled within an unnamed impact crater on the Martian North Pole, an esa release said on July 28, 2005. The water ice is located on Vastitas Borealis, a broad plain that covers much of Mars' far northern latitudes.

The crater is 35 kilometres (km) wide and has a maximum depth of approximately 2 km. The bright circular patch at its centre is residual water ice. The patch is present all year round, as the temperature and pressure are not high enough to vaporise it. esa is sure it is not frozen carbon dioxide. The hrsc also shows faint traces of water ice along the rim of the crater and on its walls. esa believes the absence of ice along the crater's northwest rim and walls may be because that area receives more sunlight.