Mars has a watery past
2005-12-01 09:37
Paris - The European spacecraft Mars Express has added powerful evidence to the belief that water once covered Mars and large reserves of precious ice lurk close to the surface today, studies presented on Wednesday said.
Surrounding Mars' North Pole are underground "layered deposits" that are believed to be fine strata of ice, according to research presented at the headquarters here of the European Space Agency (ESA).
The find is "nearly pure, cold water ice," with only 2% contamination by dust.
Beneath these deposits are large amounts of sand that is probably "cemented" with water ice.
The data was collected in three swings over the Red Planet, on June 26, July 6 and July 9, by the ESA orbiter after it had deployed a mighty ground-scanning radar called Marsis, that delved to a 1km below the planet's surface.
'Watery since childhood'
Meanwhile, scientists using a near-infrared spectrometer called Omega found wide-ranging clays called phyllosilicates - a telltale for water, for they are formed when volcanic basalt rocks are immersed in water for a long period.
They conclude that oceans covered Mars at the end of the so-called Noachian era, which concluded between 3.5 and 3.8 billion years ago.
If so, it means that Mars was watery in its childhood: the planet, like Earth, was formed around 4.6 billion years ago.
In recent years, data sent back by orbiting spacecraft and two US rovers has suggested that the planet was once awash in water and that the precious substance could still exist in the form of ice.
Finding the water could determine whether the planet once sustained life, and maybe even now harbours it, perhaps in microbial form. And a reservoir of water would be vital for a planned manned mission to the planet.
But the evidence until now has been sketchy, based mainly on images of the Martian surface, taken from land and at the surface, which show a planet dismayingly dry and dusty.
Mars Express
Mars' subsurface is "the missing third dimension," said Giovanni Picardi, a University of Rome scientist who is the Marsis chief investigator.
Mars Express, Europe's first solo mission to explore another planet, arrived at Mars on December 25 2003.
It dropped a small robot lander, Beagle 2, that disappeared without trace, and then experienced a 13-month delay in deploying the long arms of the Marsis radar, one of the most important instruments in its scientific package.
Marsis is designed to send powerful low-frequency radio waves which are capable of penetrating the ground to a depth of several kilometres.
The reflected energy is then picked up by the orbiter and transcribed to give an image of Mars's sub-surface structure.