CICLOPS: Cassini Imaging Central Laboratory for OPerationS
Epimetheus Revealed

Epimetheus Revealed
PIA 09813

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  Cassini's close flyby of Epimetheus in December 2007 returned detailed images of the moon's south polar region.

The view shows what might be the remains of a large impact crater covering most of this face, and which could be responsible for the somewhat flattened shape of the southern part of Epimetheus (113 kilometers, 70 miles across) seen previously at much lower resolution. The image also shows two terrain types: darker, smoother areas, and brighter, slightly more yellowish, fractured terrain. The darker material evidently moves down slopes, and probably has a lower ice content than the brighter material, which appears more like "bedrock." Nonetheless, materials in both terrains are likely to be rich in water ice.

This enhanced color view was created by combining a monochrome view with images taken using ultraviolet, green and infrared spectral filters, representing a slight expansion of the wavelengths of the electromagnetic spectrum visible to human eyes. The monochrome view was itself a composite of three images added together to improve the overall image quality and level of detail.

The images were taken with the Cassini spacecraft narrow-angle camera on Dec. 3, 2007. The views were obtained at a distance of approximately 37,400 kilometers (23,000 miles) from Epimetheus and at a Sun-Epimetheus-spacecraft, or phase, angle of 65 degrees. Image scale is 224 meters (735 feet) per pixel.

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.

For more information about the Cassini-Huygens mission, visit and the Cassini imaging team home page,

Credit: NASA/JPL/Space Science Institute
Released: January 11, 2008 (PIA 09813)
Image/Caption Information

Alliance Member Comments
Mercury_3488 (Feb 3, 2008 at 11:59 AM):
Most of these smaller moons appear to be 'rubble piles' of ice & maybe rock. Epimetheus, Janus, Hyperion, Telesto, Calypso, Polydeuces, Helene, etc.

Phoebe appears to be more coherent, but then Phoebe most likely formed elsewhere, maybe the Kuiper Belt, got ejected & then captured by Saturn later on.

The other smaller Saturn moons & Jupiter's Amalthea, appear to be rubble piles held together by gravity.
Red_dragon (Jan 25, 2008 at 3:50 PM):
Yes, it may be so; I think now I can see the crater. It's a luck for Epimetheus to be a porous, low-density body: if it was solid, surely it would have been destroyed.
bruno.thiery (Jan 24, 2008 at 11:13 AM):
I think the mountains in the centre are rather the central peak of this immense crater. In the South, the rim coincides with the edge of the moon itself.
Red_dragon (Jan 14, 2008 at 7:01 AM):
A very interesting image. Is the border of the crater you mention those "mountains" that can be seen in the center?