PASADENA, Calif., March 13 /PRNewswire-USNewswire/ -- Instruments on
NASA's Cassini spacecraft have found evidence for seas, likely filled with
liquid methane or ethane, in the high northern latitudes of Saturn's moon
Titan. One such feature is larger than any of the Great Lakes of North
America and is about the same size as several seas on Earth.
Cassini's radar instrument imaged several very dark features near
Titan's north pole. Much larger than similar features seen before on Titan,
the largest dark feature measures at least 39,000 square miles. Since the
radar has caught only a portion of each of these features, only their
minimum size is known. Titan is the second largest moon in the solar system
and is about 50 percent larger than Earth's moon.
"We've long hypothesized about oceans on Titan and now with multiple
instruments we have a first indication of seas that dwarf the lakes seen
previously," said Dr. Jonathan Lunine, Cassini interdisciplinary scientist
at the University of Arizona, Tucson.
While there is no definitive proof yet that these seas contain liquid,
their shape, their dark appearance in radar that indicates smoothness and
their other properties point to the presence of liquids. The liquids are
probably a combination of methane and ethane, given the conditions on Titan
and the abundance of methane and ethane gases and clouds in Titan's
atmosphere.
Cassini's visual and infrared mapping spectrometer also captured a view
of the region, and the team is working to determine the composition of the
material contained within these features to test the hypothesis that they
are liquid-filled.
The imaging cameras, which provide a global view of Titan, have imaged
a much larger, irregular dark feature. The northern end of their image
corresponds to one of the radar-imaged seas. The dark area stretches for
more than 620 miles in the image, down to 55 degrees north latitude. If the
entire dark area is liquid-filled, it would be only slightly smaller than
Earth's Caspian Sea. The radar data show details at the northern end of the
dark feature similar to those seen in earlier radar observations of much
smaller liquid-filled lakes. However, to determine if the entire dark
feature is a liquid-filled basin will require investigation through
additional radar flyovers later in the mission.
The presence of these seas reinforces the current thinking that Titan's
surface must be resupplying methane to its atmosphere, the original
motivation almost a quarter century ago for the theoretical speculation of
a global ocean on Titan.
Cassini's instruments are peeling back the haze that shrouds Titan,
showing high northern latitudes dotted with seas hundreds of miles across,
and hundreds of smaller lakes that vary from several to tens of miles.
Due to the new discoveries, team members are repointing Cassini's radar
instrument during a May flyby so it can pass directly over the dark areas
imaged by the cameras.
The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency and the Italian Space Agency. NASA's Jet Propulsion
Laboratory (JPL), Pasadena, Calif., manages the Cassini-Huygens mission for
NASA's Science Mission Directorate, Washington. The Cassini orbiter was
designed, developed and assembled at JPL.
For images and more information visit:
http://www.nasa.gov/cassini
SOURCE NASA
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Related links:
http://www.nasa.gov
CONTACT:
Dwayne Brown, Headquarters, Washington,
+1-202-358-1726, or Carolina Martinez, Jet Propulsion Laboratory,
Pasadena, Calif., +1-818-354-9382, both of NASA
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