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Mars was a benign, water-rich environment for a long period of time, American scientists have concluded after studying new information from US space agency NASA's Mars Reconnaissance Orbiter spacecraft.
Details of the new discoveries, which raise the prospect that Mars could have supported life, have appeared in Nature and Nature Geoscience.
The new data comes from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument on NASA's Mars orbiter.
It revealed evidence of vast lakes, flowing rivers and deltas on early Mars, all of which were potential habitats for microbes. Researchers said the wet conditions probably persisted for a long time.
One study shows that vast regions of Mars' ancient highlands, which cover about half the Red Planet, contain clay minerals called phyllosilicates, which can only form if water is present.
The phyllosilicates record water interacting with rocks back to the Noachian period of Martian history, which lasted from about 4.6 billion years ago to 3.8 billion years ago, a time when the Earth, the Moon and Mars were being constantly hit by comets and asteroids.
Crism's chief scientist, Scott Murchie, from the Johns Hopkins University Applied Physics Laboratory in Maryland, said that the big surprise from the new results is how pervasive and long-lasting Mars' water was, and how diverse the wet environments were.
Jack Mustard, a professor of planetary geology at the prestigious Brown University in Rhode Island, says that in most locations the rocks are lightly altered by liquid water, but in a few locations they have been so altered that a great deal of water must have flushed though the rocks and soil.
"This is really exciting because we're finding dozens of sites where future missions can land to understand if Mars was ever habitable and if so, to look for signs of past life," he says.
(c) NewsRoom 2008
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