The origin of perennial water-ice at the South Po...( by changing the precession together wi...)

The scientists set the clock 21 000 years back, when the closest vicinity of the planet to the Sun corresponded to the northern summer a situation opposite to that of today.

The model has shown that water at the North Pole was in an unstable condition and was easily transported to the South Pole in the form of water vapour, to then re-condense and freeze on the surface. Up to 1 millimetre of water ice was deposited at the South Pole every year. After Mars has spent more than 10 000 years in that climatic configuration, this accumulation led to a layer up to 6-metre thick.

About 10 000 years ago the precession cycle was inverted, and started to return to its current configuration. Water-ice at the South Pole became unstable, and was forced to progressively return back to the North.

About 1000 years ago, by a not-yet-well explained trigger mechanism, the erosion of the water-ice deposits at the South pole was blocked as soon as layers of CO2 ice were deposited on the water-ice and trapped it, as OMEGA has observed them.

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Contact: Agustin Chicarro
Agustin.chicarro@esa.int
31-071-565-3613
European Space Agency
13-Jul-2007