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 PIA09182.
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 PIA09182), 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 PIA08365), 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.