Saturday, March 3, 2012

Thin Atmosphere Found on Saturn Moon

Cassini Detects Hint of Fresh Air at Dione

This view highlights tectonic faults and craters on Dione, an icy world that has undoubtedly experienced geologic activity since its formation. This view highlights tectonic faults and craters on Dione, an icy world that has undoubtedly experienced geologic activity since its formation. Image credit: NASA/JPL/Space Science Institute
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March 02, 2012
NASA's Cassini spacecraft has "sniffed" molecular oxygen ions around Saturn's icy moon Dione for the first time, confirming the presence of a very tenuous atmosphere. The oxygen ions are quite sparse - one for every 0.67 cubic inches of space (one for every 11 cubic centimeters of space) or about 2,550 per cubic foot (90,000 per cubic meter) - show that Dione has an extremely thin neutral atmosphere.

At the Dione surface, this atmosphere would only be as dense as Earth's atmosphere 300 miles (480 kilometers) above the surface. The detection of this faint atmosphere, known as an exosphere, is described in a recent issue of the journal Geophysical Research Letters.
MORE: http://www.jpl.nasa.gov/news/news.cfm?release=2012-056&cid=release_2012-056&msource=12056&tr=y&auid=10388215

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