spacetoday.net: Scientists make case for less water on Mars

Posted: Fri, Dec 23, 2005, 10:14 AM ET (1514 GMT)
Hubble image of Mars

The planet Mars may have had less liquid water on its surface early in its history than previously expected, reducing the odds that the planet once harbored life. Researchers at the University of Colorado, in a paper published in the latest issue of Nature, said that chemical signatures found in Martian rocks by NASA's Mars Exploration Rovers could have been created instead by sulfur-bearing steam vapors moving through volcanic ash. That scenario, they said, is more consistent with the composition of the rocks than if they precipitated on a lake bed, as has been previously proposed. A separate group from Arizona State University, also writing in Nature, argued that the rock formations and sediment layers found at the rover Opportunity's landing site, which had been linked to a lake bed, may instead have been formed by the blast of an exploding meteorite. Neither paper concludes that Mars never had water, only that it did not form a lake, at least at the rover's landing site.