Saturday, December 01, 2012

NASA Spacecraft Finds New Evidence for Ice on Mercury | IIP Digital

NASA Spacecraft Finds New Evidence for Ice on Mercury | IIP Digital:
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NASA Spacecraft Finds New Evidence for Ice on Mercury

Dark radar image of Mercury with bright spots (National Astronomy and Ionosphere Center)

The bright spots in this radar image of the planet Mercury’s north polar region, taken by the Arecibo radio telescope in Puerto Rico, probably represent water ice.

Now, instruments aboard NASA’s Messenger spacecraft studying Mercury have provided compelling support for the long-held hypothesis that the planet harbors abundant water ice and other frozen volatile materials within its permanently shadowed polar craters.

“About the last thing you would expect on a planet so close to the sun is water ice,” said Matthew Siegler, a scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, and an author on one of three papers published November 29 in Science Express. “But due to Mercury’s low tilt, craters near the poles can remain in year-round shadow and be ridiculously cold.”

Scientists suggested decades ago there might be water ice and other frozen volatiles trapped at Mercury’s poles. The idea received a boost in 1991 when the Arecibo radio telescope detected radar-bright patches at Mercury’s poles. Many of these patches corresponded to the locations of large impact craters mapped by NASA’s Mariner 10 spacecraft in the 1970s. However, because Mariner saw less than 50 percent of the planet as it passed by, planetary scientists lacked a complete diagram of the poles to compare with the radar images.

Images taken from Messenger in 2011 and earlier this year confirmed all radar-bright features at Mercury’s north and south poles lie within shadowed regions on the planet’s surface. These findings are consistent with the water ice hypothesis, scientists said.

For more on the discovery, see the NASA press release.