Silica on mars volcano indicates wet and cozy past on ‘Red Planet’

Monday, November 1, 2010

LONDON - Three billion years old light-coloured piles of hydrated silica on a volcanic cone are the evidence of most recent habitable microenvironments on Mars, observes NASA.

NASA’s Mars Reconnaissance Orbiter has found that the mounds’ composition and their location on the flanks of a volcanic is the best evidence for an intact deposit from a hydrothermal environment-a steam fumarole, or hot spring.

“The heat and water required to create this deposit probably made this a habitable zone,” Nature quoted J.R. Skok of Brown University, as saying.

“If life did exist there, this would be a promising type of deposit to entomb evidence of it-a microbial mortuary,” he said.

Concentrations of hydrated silica have been identified on Mars previously, including a nearly pure patch found by NASA’s Mars Exploration Rover Spirit in 2007.

However, none of those earlier findings were in such an intact setting as the current one.

Skok said, “You have spectacular context for this deposit. It’s right on the flank of a volcano. The setting remains essentially the same as it was when the silica was deposited.”

The small cone rises about 100 meters from the floor of a shallow bowl named Nili Patera. The patera, which is the floor of a volcanic caldera, spans about 50 kilometres in the Syrtis Major volcanic region of equatorial Mars.

The collapse of an underground magma chamber from which lava had emanated created the bowl. Subsequent lava flows, still with a runny texture, coated the floor of Nili Patera.

The cone grew from even later flows, apparently after evolution of the underground magma had thickened its texture so that the erupted lava would mound up.

“We can read a series of chapters in this history book and know that the cone grew from the last gasp of a giant volcanic system,” said John Mustard, a co-author of the paper.

“The cooling and solidification of most of the magma concentrated its silica and water content,” said Mustard.

Observations by cameras on the Mars Reconnaissance Orbiter revealed patches of bright deposits near the summit of the cone, fanning down its flank, and on flatter ground in the vicinity.

Hydrated silica identified by the spectrometer in uphill locations-confirmed by stereo imaging-has indicated that hot springs or fumaroles fed by underground heating created these deposits.

Scott Murchie of Johns Hopkins University said: “The habitable zone would have been within and alongside the conduits carrying the heated water.”

The volcanic activity that built the cone in Nili Patera appears to have happened more recently than the 3.7-billion-year or greater age of Mars’ potentially habitable early wet environments recorded in clay minerals identified from orbit. (ANI)

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