Cassini Spacecraft Finds Ocean May Exist Beneath Titan's Crust
NASA's Cassini spacecraft has discovered evidence that points to the existence of an underground ocean of water and ammonia on Saturn's moon Titan.
PASADENA, Calif. - NASA's Cassini spacecraft has discovered evidence that 
points to the existence of an underground ocean of water and ammonia on 
Saturn's moon Titan. The findings, made using radar measurements of Titan's 
rotation, will appear in the March 21 issue of the journal Science."With its organic dunes, lakes, channels and mountains, Titan has one of 
the most varied, active and Earth-like surfaces in the solar system," said 
Ralph Lorenz, lead author of the paper and Cassini radar scientist at the 
Johns Hopkins Applied Physics Laboratory in Laurel, Md., "Now we see changes 
in the way Titan rotates, giving us a window into Titan's interior beneath the surface."Members of the mission's science team used Cassini's Synthetic Aperture Radar 
to collect imaging data during 19 separate passes over Titan between October 2005 
and May 2007. The radar can see through Titan's dense, methane-rich atmospheric 
haze, detailing never-before-seen surface features and establishing their locations 
on the moon's surface.Using data from the radar's early observations, the scientists and radar engineers 
established the locations of 50 unique landmarks on Titan's surface. They then 
searched for these same lakes, canyons and mountains in the reams of data returned 
by Cassini in its later flybys of Titan. They found prominent surface features had 
shifted from their expected positions by up to 30 kilometers (19 miles). A systematic 
displacement of surface features would be difficult to explain unless the moon's icy 
crust was decoupled from its core by an internal ocean, making it easier for the crust to move."We believe that about 100 kilometers (62 miles) beneath the ice and organic-rich 
surface is an internal ocean of liquid water mixed with ammonia," said Bryan Stiles 
of NASA's Jet Propulsion Laboratory in Pasadena, Calif. Stiles is a contributing author 
to the paper.The study of Titan is a major goal of the Cassini-Huygens mission because it 
may preserve, in deep-freeze, many of the chemical compounds that preceded life on Earth. 
Titan is the only moon in the solar system that possesses a dense atmosphere. The moon's 
atmosphere is 1.5 times denser than Earth's. Titan is the largest of Saturn's moons, 
bigger than the planet Mercury."The combination of an organic-rich environment and liquid water is very appealing to 
astrobiologists," Lorenz said. "Further study of Titan's rotation will let us understand 
the watery interior better, and because the spin of the crust and the winds in the atmosphere 
are linked, we might see seasonal variation in the spin in the next few years."Cassini scientists will not have long to wait before another go at Titan. On March 25, just 
prior to its closest approach at an altitude of 1,000 kilometers (620 miles), Cassini will 
employ its Ion and Neutral Mass Spectrometer to examine Titan's upper atmosphere. Immediately 
after closest approach, the spacecraft's Visual and Infrared Mapping Spectrometer will 
capture high-resolution images of Titan's southeast quadrant.The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and 
the Italian Space Agency. The mission is managed by JPL, a division of the California 
Institute of Technology in Pasadena. The Cassini orbiter also was designed, developed and 
assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, 
working with team members from the United States and several European countries.For information about Cassini visit:http://www.nasa.gov/cassiniandhttp://saturn.jpl.nasa.gov.