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LOS ALAMOS, NEW MEXICO, March 2, 2012—Los Alamos National Laboratory scientists and an international research team have announced discovery of molecular oxygen ions (O2+) in the upper-most atmosphere of Dione, one of the 62 known moons orbiting the ringed planet. The research appeared recently in Geophysical Research Letters and was made possible via instruments aboard NASA’s Cassini spacecraft, which was launched in 1997.

Dione—discovered in 1684 by astronomer Giovanni Cassini (after whom the spacecraft was named)—orbits Saturn at roughly the same distance as our own moon orbits Earth. The tiny moon is a mere 700 miles wide and appears to be a thick, pockmarked layer of water ice surrounding a smaller rock core. As it orbits Saturn every 2.7 days, Dione is bombarded by charged particles (ions) emanating from Saturn’s very strong magnetosphere. These ions slam into the surface of Dione,