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 Impact Crater with Ejecta Blanket). 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.