October 28, 2008
NASA Finds Evidence of a Wetter Mars
The U.S. space agency says its Mars Reconnaissance Orbiter has found evidence that liquid water remained on Mars far longer than previously theorized.
The National Aeronautics and Space Administration spacecraft has observed hydrated silica, or opal, spread across large regions of Mars. That, scientists said, suggests liquid water was on the planet's surface as recently as 2 billion years ago.
The newly discovered silicates formed where liquid water altered materials created by volcanic activity or meteorite impact on the Martian surface, scientists said. One such location is the large Martian canyon system called Valles Marineris.
"We see numerous outcrops of opal-like minerals, commonly in thin layers extending for very long distances around the rim of Valles Marineris and sometimes within the canyon system itself," said Ralph Milliken of NASA's Jet Propulsion Laboratory in Pasadena, Calif.
Milliken is lead author of an article describing the discovery in the November issue of the journal Geology.