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Evidence Of Ancient Sub-Surface Fluid Flows Seen On Mars

By | February 19, 2007

      Liquid or gas flowed through cracks penetrating underground rock on Mars, NASA reported.

      That disclosure stemmed from a report based on some of the first observations by the Mars Reconnaissance Orbiter.

      These fluids may have produced conditions to support possible habitats for microbial life, according to NASA.

      The ancient patterns were revealed when the most powerful telescopic camera ever sent to Mars began examining the planet last year. The camera showed features as small as approximately 3 feet across.

      Mineralization took place deep underground, along faults and fractures. These mineral deposits became visible after overlying layers eroded during millions of years.

      Chris Okubo, a geologist at the University of Arizona, Tucson, discovered the patterns in an image of exposed layers in a Martian canyon named Candor Chasma. The High Resolution Imaging Science Experiment camera aboard the orbiter took the image in September 2006.

      “What caught my eye was the bleaching or lack of dark material along the fracture. That is a sign of mineral alteration by fluids that moved through those joints,” said Okubo. “It reminded me of something I had seen during field studies in Utah, that is light-tone zones, or ‘haloes,’ on either side of cracks through darker sandstone.”

      The satellite finding could target a site for future NASA exploration.

      “This result shows how orbital observations can identify features of particular interest for future exploration on the surface or in the subsurface or from sample return,” according to Alfred McEwen, principal investigator for the camera at the University of Arizona, Tucson.

      “The alteration along fractures, concentrated by the underground fluids, marks locations where we can expect to find key information about chemical and perhaps biologic processes in a subsurface environment that may have been habitable.”

      The haloes visible along fractures seen in the Candor Chasma image appear to be raised slightly relative to surrounding, darker rock.

      This is evidence that the circulating fluids hardened the lining of the fractures, as well as bleaching it. The harder material would not erode as quickly as softer material farther from the fractures.

      “The most likely origin for these features is that minerals that were dissolved in water came out of solution and became part of the rock material lining the fractures. Another possibility is that the circulating fluid was a gas, which may or may not have included water vapor in its composition,” Okubo said.

      Discovery of significant water supplies on Mars would be enormously beneficial to future human exploration of the red planet.

      Similar haloes adjacent to fractures show up in images that the high-resolution camera took of other places on Mars after the initial Candor Chasma image. “We are excited to be seeing geological features too small to have been noticed previously,” Okubo said.

      Okubo and McEwen reported their findings in the Feb. 16 edition of the journal “Science. Images” showing the haloes along fractures. Their findings are available on the Web.

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