A spectacular landslide within the low-albedo region of Iapetus's surface known as Cassini Regio is visible in this image from Cassini.
The landslide material appears to have collapsed from a 15 kilometer (9 mile) -high scarp that forms the rim of an ancient 600-kilometer (375-mile) wide impact basin. Unconsolidated rubble from the landslide extends halfway across a conspicuous, 120-kilometer (75-mile) diameter, flat-floored impact crater that lies just inside the basin scarp.
Landslides are common geological phenomena on many planetary bodies, including Earth and Mars. However, the appearance of this landslide on an icy satellite with low-albedo cratered terrain is especially reminiscent of landslide features that were observed during the Galileo mission on another icy moon with low-albedo cratered terrains... the Jovian satellite Callisto. One Galileo image in particular (see http://photojournal.jpl.nasa.gov/catalog/PIA01095) shows landslides collapsed from the walls of two flat-floored craters on Callisto. As on Callisto, the fact that the Iapetus landslide traveled many kilometers from the basin scarp could indicate that the surface material is very fine-grained, and perhaps was fluffed by mechanical forces that allowed the landslide debris to flow extended distances.
In this view, north is to the left of the picture and solar illumination is from the bottom of the frame.
The image was obtained in visible light with the narrow angle camera on December 31, 2004, from a distance of about 123,400 kilometers (76,677 miles) from Iapetus and at a Sun-Iapetus-spacecraft, or phase, angle of 78 degrees. Resolution achieved in the original image was 740 meters (2,428 feet) per pixel. The image has been contrast-enhanced and magnified by a factor of two to aid visibility.
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.