DEPOSITS of silica detected in 2007 by the US robot Spirit on Mars were formed by volcanic vapours or hot-spring-type events crossing through soil and could contain traces of past life, scientists found in a study out today.
The silica discovery, which NASA announced briefly last year, is fully described in a paper in the May 23, 2008 issue of Science. Its lead author is Steven Squyres of Cornell University, investigator for the rover science payload.
"On Earth, hydrothermal deposits teem with life and the associated silica deposits typically contain fossil remains of microbes," said Jack Farmer, professor of astrobiology in ASU`s School of Earth and Space Exploration, part of the College of Liberal Arts and Sciences.
Prof Farmer is a co-author.
"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 said.
Prof 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 said.
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.
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