Liquid discovered on Titan's surface
Titan is thought to be the only body in our solar system beyond Earth to have liquid on its surface
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Thursday, 31, Jul 2008 08:56
Scientists claim to have discovered liquid hydrocarbons in a lake on Saturn's moon Titan, making it the only body in our solar system beyond Earth known to have liquid on its surface.
It was previously thought Titan would have global oceans made up of methane, ethane and other light hydrocarbons.
But with the spacecraft Cassini returning information from the moon, scientists have been able to determine the actual make-up of its surface.
More than 40 close fly-bys by Cassini show no such oceans exist, but hundreds of dark lake-like features are present.
An instrument onboard Cassini identified chemically different materials based on the way they absorb and reflect infrared light.
Scientists studying the information detecting liquid ethane and the visual and mapping instrument observed a lake, Ontario Lacus, in Titan's south polar region during a close Cassini fly-by in December 2007.
The lake is roughly 7,800 square miles in area, slightly larger than North America's Lake Ontario.
"This is the first observation that really pins down that Titan has a surface lake filled with liquid," said Bob Brown of the University of Arizona, Tucson.
Larry Soderblom, a Cassini interdisciplinary scientist with the US Geological Survey, added: "Detection of liquid ethane confirms a long-held idea that lakes and seas filled with methane and ethane exist on Titan.
"The fact we could detect the ethane spectral signatures of the lake even when it was so dimly illuminated, and at a slanted viewing path through Titan's atmosphere, raises expectations for exciting future lake discoveries by our instrument."
He added that over the next few years lakes and seas on Titan's north pole mapped with Cassini's radar instrument will emerge from polar darkness into sunlight, giving the infrared instrument opportunities to watch for seasonal changes of Titan's lakes.
The discovery of liquid on Titan is outlined in the journal Nature.