Dwayne Brown
Headquarters, Washington
202-358-1726
dwayne.c.brown@nasa.gov
DC Agle/Carolina Martinez
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-9011/354-9382
agle@jpl.nasa.gov, carolina.martinez@jpl.nasa.gov
RELEASE: 08-085
CASSINI SPACECRAFT FINDS OCEAN MAY EXIST BENEATH TITAN'S CRUST
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 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 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 (JPL) in,
Pasadena, Calif. Stiles also 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 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.
For information about Cassini visit:
http://www.nasa.gov/cassini/
