Washington, Nov 4 : A team of astronomers from the US and France has said that the best chance for finding life on Mars may be underground, judging by layers of clay that likely were formed in a warm, moist environment 3 to 4 billion years ago.
Early in the planet's history, the most likely locations for microbe metropolises were under the Martian surface in wet environments warmed by hydrothermal activity, according to a new study published in the journal Nature.
As the US and European space programs sent advanced orbiters and landers to explore the planet over the past decade, evidence for a warm, wet early Mars began to build, CSMonitor. com reported.
NASA's rover Opportunity found evidence of past surface-water pooling, noted Dr. Bethany Ehlmann, the lead author of the study.
More evidence came from instruments on the European Space Agency's Mars Express orbiter and later from data gathered by NASA's Mars Reconnaissance Orbiter.
"We were seeing that clays were all over the planet," as well as surface deposits of other minerals that form in the presence of water, said Ehlmann, a planetary scientist at the California Institute of Technology in Pasadena, Calif.
Data from the orbiters indicate that far more of Mars' clay deposits show a hydrothermal pedigree than a surface pedigree.
Although the constant overturning of Earth's crust has erased virtually all records of what was happening 3.5 billion years ago, some of the few rock formations geologists have found from that period show evidence for life, she explained.
Understanding the clays on Mars opens a window on a similar period and whether the environment was hospitable for life there as well.
"We think our data point to the fact that the longest-duration, water-rich environments would have been in the subsurface" on Mars, she added. (ANI)