|
Water on Mars 'underground'
08/03/2007 16:35 - (SA)
Paris - Scientists on Thursday said they had found evidence that Mars was once latticed by an underground water system, proving that the Red Planet has had a long and complex relationship with one of the potential ingredients for life.
Writing in the British journal Nature, researchers focussed on questions thrown up by Nasa's Martian rover, Opportunity, in its exploration of a vast sloping plain called Meridiani Planum.
Opportunity found sulphate-rich sediments that some experts claimed were the remains of seas that once washed over the planet.
Others, though, pointed out that the site at Meridiani Planum was not a basin, and thus could not enclose such a huge amount of water.
According to Massachusetts Institute of Technology expert Jeffrey Andrews-Hanna and colleagues, the answer is buried in the Red Planet's past - and beneath its surface.
A globally connected water system
They theorise that the water has bubbled up from underground.
The geological site in question "is in fact exactly where a global groundwater simulation model for early Mars predicts upwelling of water on the ancient planet's surface," says Victor Baker, an expert in geomorphology, in a commentary also published by Nature.
The computer model devised by Andrews-Hanna and his colleagues extends far beyond the spot where Opportunity found the hydrated sulphate salt minerals.
Drawing on other evidence of subsurface water flows - especially photos from the Mars Orbiter showing that rocks that were once below the surface have been altered by water flow - the scientists postulate what Baker calls a "globally connected groundwater system" throughout the planet.
Today Mars is bone dry, its thin atmosphere almost entirely bereft of water.
But most experts now agree that the planet was once covered with seas and a balmy, Earth-like atmosphere, fueling speculation that it could have harboured some form of life, even bacterial.
Even more tantalising, in the light of the Nature study, is recent evidence presented by Nasa scientists that some water is still flowing along the surface of Mars, presumably from underground sources.
Pictures taken by the US Mars Global Surveyor orbiter in 2005 detected two gullies that the scientists said could only have been created by a flow of liquid. The gullies had not existed when the region was photographed earlier.
Water is one of three essential ingredients for life as we know it, along with energy, such as sunlight, and elements like carbon and oxygen.
- AFP
|
News
