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Cassini finds Saturn moon Enceladus has an atmosphere, NASA says<br /><br />PASADENA, Calif. - The international Cassini spacecraft has discovered that Saturn's moon Enceladus has a significant atmosphere, NASA said Wednesday.<br /><br />The icy moon's atmosphere may be created by volcanism, geysers or gases escaping from the surface or the interior, the space agency's Jet Propulsion Laboratory said.<br /><br />Excluding Saturn's giant moon Titan, which was already known to have an atmosphere, it's the first discovery of an atmosphere on one of the more than 30 moons that orbit the ringed planet.<br /><br />Since reaching Saturn last summer, Cassini has made two close flybys of Enceladus, the shiniest object in the solar system.<br /><br />The finding was made through use of Cassini's magnetometer instrument during a Feb. 17 pass at an altitude of 725 miles of Enceladus' surface and a March 9 approach to within 310 miles.<br /><br />The instrument's observations included detection of magnetic field oscillations caused by interactions with electrically charged, or ionized, molecules. Because the frequencies of the oscillations can be used to identify the molecule, scientists believe the Enceladus observations were due to ionized water vapor.<br /><br />"These new results from Cassini may be the first evidence of gases originating either from the surface or possibly from the interior of Enceladus," Michele Dougherty, principal investigator for the Cassini magnetometer and professor at Imperial College in London, said in a statement.<br /><br />Since Enceladus is a relatively small moon - 310 miles in diameter - and the gravity it exerts is not enough to hold an atmosphere for very long, there must be a strong continuous source to maintain an atmosphere, NASA said.<br /><br />Such a source could be eruptions from volcanoes or geysers, which would put Encel <div class="Discussion_UserSignature"> </div>