False color images of Saturn's moon, Mimas, reveal variation in either the composition or texture across its surface.
During its approach to Mimas on August 2, 2005, the Cassini narrow angle camera obtained multispectral views of the satellite from a range of 228,000 km (142,500 miles). One such false-color view is shown here. The image at left is a narrow angle clear-filter image which was separately processed to enhance the contrast in brightness and sharpness of visible features. The image at right is a color composite of narrow angle ultraviolet (UV3), green (GRN), infra-red (IR3) and clear (CLR) filter images which have been specially processes to accentuate subtle changes in the spectral properties of Mimas' surface materials. To create this view, three color images (UV3, GRN, and IR3) were combined into a single black and white picture that isolates and maps regional color differences. This "color map" was then superposed over the clear-filter image at left.
The combination of color map and brightness image shows how the color differences across the Mimas surface materials are tied to geological features. Shades of blue and violet in the image at right are used to identify surface materials that are bluer in color and have a weaker infrared brightness than average Mimas materials, which are represented by green.
Herschel crater, a 140 km (88 mile) wide impact feature with a prominent central peak, is visible in the upper right in each image. The unusual bluer materials are seen to broadly surround Herschel crater. However, the bluer material is not uniformly distributed in and around the crater. Instead, it appears to be concentrated on the outside of the crater and more to the west than to the North or South. The origin of the color differences is not yet understood. It may represent ejecta material that was excavated from inside of Mimas when the Herschel impact occurred. The bluer color of these materials may be caused by subtle differences in the surface composition or the sizes of grains making up the icy soil.
The images were obtained when the Cassini spacecraft was above 25S, 134W latitude and longitude. The Sun-Mimas-spacecraft angle was 45 degrees and north is at the top.
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 Cassini-Huygens mission for NASA's Science Mission Directorate, Washington, D.C. The imaging team consists of scientists from the US, England, France, and Germany. The imaging operations center and team lead (Dr. C. Porco) are based at the Space Science Institute in Boulder, Colo.