CICLOPS: Cassini Imaging Central Laboratory for OPerationS
Rhea's Western Wisps

Icy fractures on Saturn's moon Rhea reflect sunlight brightly in this high-resolution mosaic created from images captured by NASA's Cassini spacecraft during its March 2, 2010, flyby. This flyby was the closest flyby of Rhea up to then.

This mosaic of six images shows the westernmost portion of the moon's "wispy" terrain. (See PIA06578 and PIA08120 to learn more.) Among the interesting features depicted here is a very straight east-west fracture near the top center of the mosaic that intersects two north-south fractures. The large crater at the bottom left of the mosaic is Inmar (55 kilometers, 34 miles across).

The closest approach of the spacecraft to Rhea during this encounter was 100 kilometers (62 miles). These images were obtained approximately half an hour later at an altitude of about 16,000 kilometers (10,000 miles).

This mosaic shows part of the side of Rhea (1528 kilometers, 949 miles across) that always faces Saturn. The images were re-projected in an orthographic projection centered on terrain at 7 degrees north latitude, 296 degrees west longitude. The mosaic itself shows terrain centered on terrain at 6 degrees north latitude, 293 degrees west longitude. North on Rhea is roughly up in the image.

The images were taken with the Cassini spacecraft narrow-angle camera. The view was obtained at a sun-Rhea-spacecraft, or phase, angle of 2 degrees. So, Cassini was almost directly between Rhea and the sun as it acquired these images. Image scale is 85 meters (280 feet) per pixel.

The Cassini Solstice Mission is a joint United States and European endeavor. 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 was designed, developed and assembled at JPL. 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 Solstice Mission visit, and

Credit: NASA/JPL/Space Science Institute
Released: December 21, 2010 (PIA 12809)
Image/Caption Information
  Rhea's Western Wisps
PIA 12809

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Alliance Member Comments
Dragon_of_Luck_Mah_Jonng1971 (Jan 17, 2011 at 2:34 PM):
Those icy fractures remind me on Dione.
lsludwig1 (Dec 21, 2010 at 5:16 PM):
Regarding PIA12809, the new closeup of Rhea's main fractures, I detect some 'smudging' in the central fracture line showing the bright cliffs which to me look like what vapor jets would look like from a fissure as we have seen on Enceladus. Likely it is just a smudge in the image, but it did catch my attention as I panned down an enlarged view of this image. Comments?