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November 27, 2010
First Oxygen in Atmosphere Discovered Beyond Earth. "The new results suggest that active, complex chemistry involving oxygen may be quite common throughout the solar system and even our universe."
- Ben Teolis, Ph.D., Cassini Team, Southwest Research Institute, San Antonio, TX
Légende de l'image : Saturn's second largest moon, icy Rhea, now is confirmed by NASA's
Cassini spacecraft to have a tenuous atmosphere of oxygen and carbon dioxide.
Saturn's largest moon, Titan, has a thick nitrogen-methane atmosphere,
but very little carbon dioxide and oxygen.
NASA: “This is the first time a spacecraft (Cassini) has directly captured molecules of an oxygen atmosphere – albeit a very thin one -- at a world other than Earth. The oxygen appears to arise when Saturn's magnetic field rotates over Rhea. Energetic particles trapped in the planet's magnetic field pepper the moon's water-ice surface. They cause chemical reactions that decompose the surface and release oxygen. The source of the carbon dioxide is less certain. Oxygen at Rhea's surface is estimated to be about 5 trillion times less dense than what we have at Earth. But the new results show that surface decomposition could contribute abundant molecules of oxygen, leading to surface densities roughly 100 times greater than the exospheres of either Earth's moon or Mercury. The formation of oxygen and carbon dioxide could possibly drive complex chemistry on the surfaces of many icy bodies in the universe.” See
JPL Cassini.
Source :
http://www.earthfiles.com/
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