NASA study suggests watery underground on Mars

[News_Editor]

NASA study suggests watery underground on Mars

2011-11-03 08:27:49 GMT+7 (ICT)

WASHINGTON, D.C. (BNO NEWS) -- Life on the planet Mars, if it ever existed, would most likely have taken place below the planet's surface, according to a new study released by NASA on Wednesday.

After analyzing years of mineral-mapping data of the so-called 'Red Planet', a new interpretation suggests that Martian environments with abundant liquid water on the surface existed only during short episodes.

From more than 350 sites on Mars examined by European and NASA orbiters, scientists believe these short episodes occurred toward the end of hundreds of millions of years during which warm water interacted with subsurface rocks. This has implications about whether life existed on Mars and how its atmosphere has changed.

This new study supports an alternative hypothesis that persistent warm water was confined to the subsurface and many erosional features were carved during brief periods when liquid water was stable at the surface.

"If surface habitats were short-term, that doesn't mean we should be glum about prospects for life on Mars, but it says something about what type of environment we might want to look in," said the report's lead author, Bethany Ehlmann, assistant professor at the California Institute of Technology and scientist at NASA's Jet Propulsion Laboratory in Pasadena. "The most stable Mars habitats over long durations appear to have been in the subsurface. On Earth, underground geothermal environments have active ecosystems."

John Mustard, professor at Brown University in Providence, Rhode Island, and a co-author of the study, stated that the types of clay minerals which formed in the shallow subsurface are all over Mars. The types that formed on the surface, however, are found at very limited locations and are rare.

The clay minerals on Mars were discovered in 2005, indicating that the planet once hosted warm and wet conditions. If those conditions existed on the surface for a long era, the planet would have needed a much thicker atmosphere than it has now to keep the water from evaporating or freezing. Researchers have been searching for evidence of processes that could cause a thick atmosphere to be lost over time.

The discovery of clay minerals by the OMEGA spectrometer on the European Space Agency's Mars Express orbiter added to earlier evidence of liquid Martian water. Clay forms from the interaction of water with rock and different types of clay minerals result from different types of wet conditions.

One clue helping scientists develop the new hypothesis was the detection of a mineral called prehnite. It forms at temperatures above about 400 degrees Fahrenheit (about 200 degrees Celsius), temperatures which are typical of underground hydrothermal environments rather than surface waters.

"Our interpretation is a shift from thinking that the warm, wet environment was mostly at the surface to thinking it was mostly in the subsurface, with limited exceptions," said Scott Murchie of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.

One of those exceptions may be Gale Crater, the site targeted by NASA's Mars Science Laboratory mission. Launching this year, the Curiosity rover will land and investigate layers that contain clay and sulfate minerals.

NASA's Mars Atmosphere and Volatile Evolution Mission, or MAVEN, in development for a 2013 launch, may provide evidence for or against this new interpretation of the Red Planet's environmental history. The report predicts MAVEN findings consistent with the atmosphere not having been thick enough to provide warm, wet surface conditions for a prolonged period.

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