Dwayne Brown
Headquarters, Washington
202-358-1726
Carolina Martinez
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-9382
RELEASE: 07-64
CASSINI SPACECRAFT IMAGES SEAS ON SATURN'S MOON TITAN
Pasadena, Calif. - 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.
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