Figure 1: Titan Crater in Three Views
This three-panel image shows one of Titan's most prominent impact craters
in an infrared-wavelength image (left), radar image (center) and in the
false-color image (right). The Cassini radar imaged this crater during
Cassini's third flyby of Titan, on Feb. 15, 2005, (see PIA07368).
The crater, located at 16 degrees west, 11 degrees north, is about 80
kilometers (50 miles) in diameter and is surrounded beyond that by a
blanket of material thrown out of the crater during impact. In radar,
brighter surfaces mean rougher terrains, or else terrains tilted toward
the radar.
Two Titan flybys later, on April 16, the visual infrared mapping
spectrometer on Cassini obtained images of the same crater. The panel on
the left is an image at the 2.0 micron wavelength, showing that the crater
has a dark floor and a small bright area in the center. The crater is
surrounded by bright material, which has a very faint halo slightly darker
than the surrounding dark material. Compare the radar image with the
visual infrared mapping spectrometer image. Both the crater and the
blanket of surrounding material (called ejecta) are bright at radar
wavelengths; in the infrared, the crater itself is dark and this blanket
of material is quite bright. In radar, the faint halo surrounding the
blanket of material is quite similar in appearance to the rest of the
ejecta blanket.
The right hand panel is a false-color visual infrared mapping spectrometer
image of the crater at lower resolution. It shows the faint halo to be
slightly bluer than surrounding material. That the material is bluer than
its surroundings, while also being darker, suggests that the faint halo
is somewhat different in composition. This suggests that the composition
of Titan's upper crust varies with depth, and various materials were
excavated when the crater was formed.
The same structure appearing so different to different instruments
illustrates the importance of multiple instruments studying such
phenomena. The Cassini spacecraft, being the most interdisciplinary
spacecraft ever flown, strongly embodies such an approach.
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 and its two onboard cameras were designed, developed and
assembled at JPL. The radar instrument team is based at JPL, working with
team members from the United States and several European countries. The
visual and infrared mapping spectrometer team is based at the University
of Arizona, Tucson.
For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov.
For more information about the visual and infrared mapping spectrometer
visit http://wwwvims.lpl.arizona.edu/.
