PASADENA, Calif., March 20 /PRNewswire-USNewswire/ -- 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:
www.nasa.gov/cassini
SOURCE NASA
Dwayne Brown, Headquarters, Washington, +1-202-358-1726,
dwayne.c.brown@nasa.gov, or DC Agle or Carolina Martinez, Jet Propulsion
Laboratory, Pasadena, Calif., +1-818-393-9011, +1-818-354-9382,
agle@jpl.nasa.gov, carolina.martinez@jpl.nasa.gov, all of NASA
