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Mars rover finds mineral vein left by flowing water
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Mars Rover Opportunity has found a mineral vein that appears to have been left on the Red Planet by flowing water.
While this type of mineral, known as gypsum, has been found previously on Mars, those finds were in the form of sand blown from an unknown source. This is the first time a vein of the mineral has been found in the same location where it was believed to have been formed.
"This tells a slam-dunk story that water flowed through underground fractures in the rock," Steve Squyres, principal investigator for Opportunity and a Cornell University astronomer, said in a statement. "This stuff is a fairly pure chemical deposit that formed in place right where we see it."
Squyres and his colleagues announced the findings Wednesday at an American Geophysical Union conference in San Francisco.
Opportunity found the mineral vein, which is about as wide as a human thumb and nearly half a metre long, on an apron surrounding the rim of the Mars Endeavour Crater.
In November, the rover examined it using a panoramic camera and its alpha particle X-ray spectrometer, built by a German team that included Ralf Gellert, now a physics professor at the University of Guelph in Ontario. The spectrometer detects the type and amounts of elements present in a rock sample.
Gellert and Richmond, B.C.-based MacDonald, Dettwiler and Associates Ltd. have built a more advanced version for Curiosity, the newest Mars rover, which began its journey to Mars on Nov. 26.
The spectrometer found that the mineral vein was relatively pure calcium sulphate. Data from the camera suggested that the mineral was in the form of gypsum, containing lots of water within its crystals. On Earth, gypsum is used to make drywall and plaster of Paris.
The mineral composition of the vein suggests it likely formed from water dissolving calcium out of volcanic rocks and sulphur from other volcanic rocks or the volcanic gas. Scientists think it originally formed in an underground fracture that has since become exposed to the surface.
Ray Arvidson, deputy principal investigator for the mission and a planetary sciences professor at Washington University in St. Louis, Mo., said scientists want to understand why the vein formed on the apron of the crater, but not on the Meridiani plain that Opportunity crossed on its way to the crater.
The new finding adds to other evidence gathered during Opportunity's travels across Mars that suggest it was a wet environment billions of years ago.
Opportunity and its rover twin, Spirit, arrived on Mars in January 2004. Their missions were officially supposed to last three months, but Spirit continued communicating until 2010 and Opportunity continues exploring and sending data back to Earth.
Curiosity is set to arrive on Mars in August.
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