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Water Ice Found Near South Pole of Mars
By Robert Roy Britt
Senior Science Writer
posted: 02:01 pm ET
05 December 2002
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Water ice has been discovered on the surface of Mars near the fringes of the southern polar cap, extending the detection of frozen water to three regions of the Red Planet. Researchers had previously found frozen water beneath Martian soil in the southern hemisphere and at the surface of the northern cap. They had been puzzled over the lack of a similar finding in the icy southern cap. Only frozen carbon dioxide, commonly called dry ice, had been found there. Other researchers have suggested in previous studies that the dry ice makes up but a thin layer that hides a deep water ice cap. The new discovery, made with NASA's orbiting Odyssey spacecraft and announced today, could support this idea, said study leader Timothy Titus of the U.S. Geological Survey. "This discovery of exposed water ice may be just the tip of the Martian iceberg," Titus told SPACE.com. Other images taken with Odyssey's infrared camera "suggest that the southern perennial cap edge may be surround by exposed water ice that extents 1-10 kilometers [0.6 to 6.0 miles] out." The finding was made by watching how surface temperatures change from night to day. "Sand and dust heat up quickly," Titus explained. "Rocks heat up slowly and water ice heats up the slowest of all."The research is detailed in the online version of the journal Science. Earlier this year, scientists used a different instrument on Odyssey to locate vast quantities of hydrogen just under the surface of Mars, in the southern hemisphere and away from the polar cap. The hydrogen almost surely represents water ice, they said. Combined, the three findings suggest that frozen water is virtually ubiquitous on Mars. But it has not yet been determined if any of it exists in liquid form, a requirement for life. Odyssey, with a price tag of nearly $300 million, launched April 7, 2001, will continue the search for liquid water. It studies Mars from 249 miles (400 kilometers) above and will map the planet in visible and infrared light in unprecedented detail, scientists say. The infrared measurements have an outside chance of detecting comparatively warm pools of subsurface liquid water, if any exist, according to Philip Christensen, an Arizona State University geologist in charge of the cameras on Odyssey. Christensen participated in the findings announced today.
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