September 24, 2009
NASA Orbiter Finds Ice In New Craters On Mars
NASA's Mars Reconnaissance Orbiter has discovered water that could be 99 percent pure in craters halfway between the north pole and equator of Mars.
"We knew there was ice below the surface at high latitudes of Mars, but we find that it extends far closer to the equator than you would think, based on Mars' climate today," said Shane Byrne of the University of Arizona, a member of the High Resolution Imaging Science Experiment, or HiRISE, which runs the high-resolution camera on NASA's Mars Reconnaissance Orbiter.The discovery marks the first time scientists have found ice so close to the surface and so far south on the planet.
"The other surprising discovery is that ice exposed at the bottom of these meteorite impact craters is so pure," Byrne said. "The thinking before was that ice accumulates below the surface between soil grains, so there would be a 50-50 mix of dirt and ice. We were able to figure out, given how long it took that ice to fade from view, that the mixture is about one percent dirt and 99 percent ice."
Scientists used instruments featured on the MRO to confirm pure, bright ice in craters from 1.5 feet to 8 feet deep, at five different locations on the Red Planet.
In August 2008, researchers used MRO's Context camera to determine if any dark spots or other changes were visible.
In September 2008, the HiRISE team captured high-resolution images of the dark spots.
"We saw something very unusual when we followed up on the first of these impact craters," Byrne said, "and that was this bright blue material poking up from the bottom of the crater. It looked a lot like water ice. And sure enough, when we started monitoring this material, it faded away like you'd expect water ice to fade, because water ice is unstable on Mars' surface and turns directly into water vapor in the atmosphere."
Byrne and colleagues reported their findings in the journal Science.
Image Caption: The HiRISE camera on NASA's Mars Reconnaissance Orbiter took this image of a new, 8-meter (26-foot)-diameter meteorite impact crater in the topographically flat, dark plains within Vastitas Borealis, Mars, on November 1, 2008. The crater was made sometime after Jan. 26, 2008. Bright water ice was excavated by, and now surrounds, the crater. This entire image is 50 meters (164 feet) across. Credit: NASA/JPL-Caltech/University of Arizona
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