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. Image credit:
NASA/JPL/Space Science Institute
› Full image and caption
|
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
gaw
Glenn A. Walsh, Project Director,
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