Click on the image for movie of
An Ocean Runs Through It
This graphic and animation depicts a cross-section of the Saturnian moon
Titan. Cassini scientists speculate there may be a layer of liquid water
mixed with ammonia about 100 kilometers (62 miles) below the surface of
Titan.
The assumption that Titan contains an internal ocean was generated from
data gleaned from Cassini's Synthetic Aperture Radar during 19 separate
passes over Titan between October 2005 and May 2007. 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. What they found was
prominent surface features seemed to shift from their expected positions
by up to 31 kilometers (19 miles). Since the features could not have
really moved, the apparent shift told the scientists and engineers that
Titan was spinning about its axis in a previously unsuspected manner. The
pre-Cassini model of Titan's spin accounted for the gravitational fields
of Saturn and other nearby planets and moons but omitted other smaller
less well understood effects. Since the observed spin of Titan does not
fit this model, other influences, such as the seasonal changes in the
motion of its atmosphere must also be important. It is difficult to
explain how such relatively low energy phenomena could have such a
pronounced influence on Titan's spin unless the moon's icy crust was
decoupled from its core by an internal ocean. If the crust were decoupled
from the core, atmospheric fluctuation alone could account the observed
spin.
The Cassini-Huygens mission is a cooperative project of NASA, the European
Space Agency and the Italian Space Agency. NASA's Jet Propulsion
Laboratory, a division of the California Institute of Technology in
Pasadena, manages the mission for NASA's Science Mission Directorate,
Washington, D.C. The Cassini orbiter 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 more information about the Cassini-Huygens mission, visit
http://saturn.jpl.nasa.gov/home/index.cfm.
