July 27, 2007
Cassini's radar instrument obtained another in its series of north polar swaths of Titan on April 10, 2007. This image exposes more of the transition between the mid-latitudes and the polar area, and extends coverage of the lakes region previously described in Titan (T25) Viewed by Cassini's Radar - Feb. 22, 2007.
This swath begins at 20 degrees south, 37 degrees west, continuing approximately north-northeast. Although it appears to be straight in this image, its path on Titan curves gently toward the east until it reaches 80 degrees north at 300 degrees west, then it turns south and ends at 51 degrees north, 213 degrees west. The swath width varies from about 200 kilometers (120 miles) at its center to about 500 kilometers (310 miles) at the ends, and is more than 6,700 kilometers (4,100 miles) long.
Beginning at the left end of the image as shown, we see the dark sinuous features previously interpreted to be dunes, interspersed with bright features that appear to be higher. In some cases the dunes seem to bend around the bright features, and in others they may be climbing up onto them; both behaviors are commonly seen in dune fields on Earth. About one-third of the way through the swath, the dunes become rare and then disappear, to be replaced by more linear features. Some of these have rounded and brighter ends, similar to lava flows on Earth (in synthetic aperture radar images, rougher features appear as bright). Just past the midway point, we find relatively flat and featureless terrain with some structures that also resemble flow fronts, followed by a complex area of semi-circular to irregular depressions that may have formed by collapse. These give way to the lakes at the northernmost portion. Here T28 overlaps with the T25 synthetic aperture radar swath (see Titan (T25) Viewed by Cassini's Radar - Feb. 22, 2007), offering stereo coverage that will be used to determine feature heights.
The lakes, which are thought to be filled with a combination of methane and ethane, have complex shorelines that often include channels. Some of these channels have well-developed tributary systems and drain many thousands of square kilometers of the surrounding terrain. As shown in the mosaic (see Exploring the Wetlands of Titan), these lakes are likely connected, and may form part of a larger sea. Brighter areas within the lakes may represent the lake bottom ¿ at the radar's 2-centimeter wavelength, it is possible that the liquid is transparent for many tens of meters (tens of yards) to the radar, allowing a reflection to be returned from the lake bottom.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The 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/home/index.cfm.