Scheduled for launching in late August, NASA's Curiosity rover will help scientists unravel the Martian environment and whether it has conditions suitable for life. Image Credit/NASA illustration
Life on Mars — if it ever arose — most likely flourished underground, according to scientists, who base their new conclusions on clay minerals detected by a pair of U. S. and European spacecraft circling the Red Planet.
The findings, collected from mineral mapping data gathered at 350 sites on Mars, were published in the latest editions of Nature, the British science journal.
The conclusions do not rule out the presence of water on the planet’s surface, but they do suggest it flowed and ponded for only brief periods interrupted by hundreds of millions of years. The findings challenge previous thinking that Mars was once a warmer environment with a thick atmosphere.
Today, the Martian atmosphere is so thin that water boils quickly away.
The discovery of clay minerals on Mars was made in 2005 by the European Space Agency’s Mars Express orbiter, launched two years earlier.
Artist's illustration of the Mars Express. Image Credit/ESA
Clays form on Earth from the interaction of water and rock. Different types of clays reflect correspondingly different wet conditions.
“The types of clay minerals that formed in the shallow subsurface are all over Mars,” said John Mustard, a Brown University researcher and co-author of the Nature study. “The types that formed on the surface are found at very limited locations and are quite rare.”
NASA’s Mars Reconnaissance Orbiter, launched in 2005, launch joined the search for clay minerals.
Clays that form where the ratio of water to rock is low in general retain the chemical signature of the original volcanic environment in which they formed.
The Mars Reconnaissance Orbiter races above the Martian terrain in this NASA illustration. Image Credit/NASA image
The study by Mustard and his colleagues suggests that is the case for most Martian landforms with iron and magnesium clays. In contrast, surface environments with more water than rock, alter the rocks further. When the water soluble elements are carried off, a range of aluminum rich clays remain.
“Our interpretation is a shift from thinking that the warm, wet environment was mostly on the surface to thinking it was mostly in the subsurface,” said Scott Muchie, of Johns Hopkins University, another of the study’s authors.
Gale Crater may be an exception.
That is the destination for NASA’s Mars Science Laboratory, a large rover equipped with lab tools to investigate the suitability of the terrain for past or present life. Also known as Curiosity, MSL is being prepared for a lift off from the Cape Canaveral Air Station,Fla., between Nov. 25 and Dec. 18.
Curiosity is expected to reach Mars next August.