In the nick of time, the Cassini spacecraft snapped this image of the
eastern rim of Saturn's moon Rhea's bright, ray crater. The impact event
appears to have made a prominent bright splotch on the leading hemisphere
of Rhea (see PIA06648). Because Cassini was traveling so fast relative
to Rhea as the flyby occurred, the crater would have been out of the
camera's field of view in any earlier or later exposure.
The crater's total diameter is about 50 kilometers (30 miles), but this
rim view shows details of terrains both interior to the crater and outside
its rim. The prominent bright scarp, left of the center, is the crater
wall, and the crater interior is to the left of the scarp. The exterior of
the crater (right of the scarp) is characterized by softly undulating
topography and gentle swirl-like patterns that formed during the
emplacement of the large crater's continuous blanket of ejecta material.
Numerous small craters conspicuously pepper the larger crater's floor and
much of the area immediately outside of it. However, in some places, such
as terrain in the top portion of the image and the bright crater wall, the
terrain appears remarkably free of the small impacts. The localized "shot
pattern" and non-uniform distribution of these small craters indicate that
they are most likely secondary impacts -- craters formed from fallback
material excavated from a nearby primary impact site. Because they exist
both inside and outside the large crater in this image, the source impact
of the secondary impacts must have happened more recently than the impact
event that formed the large crater in this scene.
This is one of the highest-resolution images of Rhea's surface obtained
during Cassini's very close flyby on Nov. 26, 2005, during which the
spacecraft swooped to within 500 kilometers (310 miles) of the large moon.
Rhea is 1,528 kilometers (949 miles) across and is Saturn's second largest
moon, after planet-sized Titan.
The clear filter image was acquired with the wide-angle camera at an
altitude of 511 kilometers (317 miles) above Rhea. Image scale is about 34
meters (112 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 mission for NASA's Science Mission Directorate, Washington, D.C. The
Cassini orbiter and its two onboard cameras were designed, developed and
assembled at JPL. The imaging operations center is based at the Space
Science Institute in Boulder, Colo.
For more information about the Cassini-Huygens mission visit
http://saturn.jpl.nasa.gov. The Cassini imaging team homepage is at
http://ciclops.org.
