On the final flyby of Cassini's original four-year tour, its radar mapper
captured these unusual channels on Titan at the edge of Xanadu, the widest
seen in this area (For a radar image of Xanadu see PIA08428). These might be
active rivers carrying methane or debris, or they might be dry riverbeds
similar to earthly arroyos.
Past Cassini radar images have revealed different types of channels on
Titan's surface (see PIA03565 and PIA07366). They vary from bright to dark
in radar (rough to smooth), and from fan-shaped to braided to meandering.
Some drain into lakes, others disappear. Some of these channels may be
several hundred meters, or feet, deep.
This image, taken from the flyby on May 28, 2008, shows the border of
Xanadu as the bright-dark boundary running from the upper left to lower
right. Southward from that boundary is an unusual set of channels. While
these are brighter (more roughly textured) than the surrounding terrain,
some are only slightly brighter, and some are as wide as 5 kilometers
(about 3 miles)—about the size of the River Thames at its mouth east
of London. They appear to flow out of the rough region of Xanadu. Careful
inspection reveals smaller tributaries that wind through the brighter and
apparently rougher terrain to the north. A close-up of one of the widest
channels is shown at the lower left.
Scientists think that many of the channels on Titan are carved by methane
deposited on the surface from strong but infrequent rainstorms. A bright
channel may be dry, with the rough riverbed of icy particles (like those
seen at the Huygens landing site) producing the radar brightness. The
darker channels in this image resemble the dry lakes seen in the north
polar area of Titan, so they may be dry as well, with their smoother
(radar-dark) surfaces caused by finer-grained sediment deposits on the
channel floors.
This image shows an area located at 15 degrees south latitude and 121
degrees west longitude. It is about 450 kilometers (280 miles) across, and
has approximately 1 kilometer (0.62-mile) resolution. North is up.
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/.
