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Methane Lakes Dot Surface of Saturn's Moon

28 July 2006

New data about Titan's surface, atmosphere come from international mission

Washington – The Cassini spacecraft has detected lakes on Saturn’s moon Titan, and in doing so, identified the apparent source of the hydrocarbons in the Titan’s atmosphere.

A July 28 announcement from NASA’s Jet Propulsion Laboratory (JPL) about the mission’s latest finding described it as a “significant accomplishment.”  

Radar images taken during a July 22 flyby of Titan reveal well-defined dark patches that resemble Earth’s lakes, but most likely are brimming with methane or a combination of methane and ethane, due to the orb’s frigid temperatures in the range of minus 180 degrees Celsius.

The recent flyby was Cassini’s first view of this region of the Saturn moon, and the radar spotted several dozens of these dark patches, some as small as 1 kilometer across and some almost 36 kilometers across.

“What we see is darker than anything we’ve ever seen elsewhere on Titan,” said Larry Soderblom, a Cassini interdisciplinary scientist at the U.S. Geological Survey in Flagstaff, Arizona. “Titan has turned out to be like a musical crescendo – each pass is more exciting than the last.”

The Cassini-Huygens mission is a cooperative project among NASA, the European Space Agency (ESA) and Agenzia Spaziale Italiana, the Italian space agency. JPL manages the Cassini-Huygens mission for NASA's Science Mission Directorate.

The unmanned, scientific mission launched in 1997, reached the ringed planet in 2004 on a four-year mission to study Saturn and its 31 moons. Cassini sent the ESA's Huygens probe drifting down to the surface of Titan in 2005. (See related article.)

Scientists had predicted that pools of liquid were contributing to the high concentration of methane and other hydrocarbons in Titan’s atmosphere, which form a dense smog that obscures visible images. Radar can penetrate the smog to provide images of the surface, thus providing some confirmation to the prediction about the liquid on the surface.

“We’ve always believed Titan’s methane had to be maintained by liquid lakes or extensive underground ‘methanofers,’ the methane equivalent of aquifers,” Jonathan Lunine, a Cassini scientist at the University of Arizona, Tucson, said. “We can’t see methanofers, but we can now say we’ve seen lakes.”

Future flybys of this region of Titan will give opportunity for the accumulation of more images, which may offer further clues to their nature -- how they rise and fall with time and seasons and whether winds might alter their surfaces and brightness.

(Distributed by the Bureau of International Information Programs, U.S. Department of State. Web site: http://usinfo.state.gov)