Frozen lake on the Red Planet?
Scientists led by John Murray of UK's Open University say the evidence comes from pictures sent home by European Space Agency's Mars Express orbiter.
Claims that life or the potential for it exists on Mars were boosted on Wednesday when scientists declared they saw the remains of a frozen sea on the planet's surface and speculated the ice may hold preserved organisms.
Planetary geologists led by John Murray of Britain's Open University said the evidence comes from pictures sent home by the European Space Agency's Mars Express orbiter.
High resolution, stereoscopic images reveal a flat, "plate-like terrain" in the region of southern Elysium Planitia, near the Martian equator, that appears remarkably like fields of pack ice on Earth, they say.
The "frozen lake" measures about 800 by 900 kilometres long and is probably about 45 metres deep on average, making it similar in size and depth to the North Sea.
"If our interpretation is confirmed, this is a place that might preserve evidence of primitive life, if it has ever developed on Mars," the group ventures in Nature, the British science weekly.
The apparent lake lies at the west end of Athabasca Vallis, an outflow channel leading from a trench called Cerberus Fossae.
Murray's team contends the water is the relic of an ocean created from sub-surface ice that was melted by volcanic activity and gushed to the surface along the Cerberus Fossae.