The South Pole of Mars contains enough ice to cover the planet in 35 feet of water if it melted, new radar scans have determined. The North Pole, researchers said, probably holds about as much.

The new measurements, made by a joint NASA-Italian Space Agency instrument on the European Space Agency Mars Express, also found that the Martian ice is filled with wind-blown dust, which makes up about 10 per cent of the polar ice cap. While planetary scientists have known for some time that Mars has large amounts of ice at its poles, the newest measurements are said to be the most precise and revealing. They found, for instance, that some of the ice deposits are more than two miles thick, and that the crust beneath the ice sheet is often rugged and cratered.

The study, published in last week’s edition of Science, describes preliminary information suggesting the existence of liquid water at the bottom of the South Pole. The warmer temperatures required to melt the ice would probably come from geothermal heat deep within the planet.

Jeffrey Plaut of NASA’s Jet Propulsion Laboratory in Pasadena, California, who led the study, said the findings built on previous, similar estimates. But he said that because the research “mantra” regarding Mars is “follow the water,” any additional information about its presence is important.

Scientists generally believe that life occurs only where water exists. Plaut said that while the deposits of frozen ice at the Martian poles are substantial, they are not great enough to explain the very deep canyons and cuts in the planet’s surface that appear to have been caused by much greater amounts of water. “The big mystery of Mars,” he said, “is where did the rest of the water go?”