May 22, 2008 -- Deposits of silica detected on Mars in 2007 by the roving robot Spirit were formed by volcanic vapors or hot-spring-type events crossing through soil.
They could also contain traces of past life, scientists reported in a study out Thursday.
The silica discovery, which NASA announced briefly last year, is fully described in paper in the May 23, 2008 issue of Science. Its lead author is Steven Squyres of Cornell University, an investigator for the rover science mission.
"On Earth, hydrothermal deposits teem with life, and the associated silica deposits typically contain fossil remains of microbes," said Jack Farmer, a professor of astrobiology in ASU's School of Earth and Space Exploration, part of the College of Liberal Arts and Sciences. Farmer is a co-author on the new study.
"But we don't know if that's the case here," Farmer noted, "because the rovers don't carry instruments that can detect microscopic life."
"What we can say is that this was once a habitable environment where liquid water and the energy needed for life were present," he added.
Farmer said hydrothermal systems generally yield silica and other minerals as heated groundwater rises, cools and gives off dissolved gases.
"If there were organisms living there," he said, "our terrestrial experience shows that microbes can easily be entrapped and preserved in the deposits." Silica is an excellent medium for capturing and preserving traces of microbial life, he added.
NASA landed two Mars rovers, Spirit and Opportunity, on opposite sides of the planet in January 2004 to scope out rocks showing the presence of water. Now the rovers are more than four Earth years into a trek designed to go just three months.
While dust has collected on their solar panels and they have had some mechanical wear, both are still exploring.
Discovery News will be blogging live about the latest Mars mission from the Phoenix flight control center at the Jet Propulsion Laboratory in Pasadena, Calif., beginning Thursday, May 22.
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