In its own way, the shepherd moon Prometheus (102 kilometers, 63 miles
across) is one of the lords of Saturn's rings. The little moon maintains
the inner edge of Saturn's thin, knotted F ring, while its slightly
smaller cohort Pandora (84 kilometers, or 52 miles across) guards the
ring's outer edge.
This view is a composite of nine raw images combined in a way that
improves resolution and reduces noise. The final image was magnified by a
factor of five. One of the component images was previously released (see PIA06098).
The image clearly shows that Prometheus is not round, but instead has an
oblong, potato-like shape. The moon was discovered during the Voyager
mission, and scientists then noted ridges, valleys and craters on its
surface. Hints of its varied topography are present in this view, although
Cassini will likely obtain much better images of Prometheus later in the
mission.
The component images were taken over about ten and a half minutes. During
that time, the spacecraft's motion caused some blurring of the F ring in
the background. Cassini was below the ring plane at the time the images
were obtained, and the view here is across the rings toward the distant
arm of the F ring. Sunlight is coming from below left.
These images were obtained with the Cassini spacecraft wide angle camera
on July 1, 2004, around the time Cassini entered Saturn's orbit. The
spacecraft's distance from the planet ranged from approximately 181,000
to 190,000 kilometers (112,000 to 118,000 miles) during the time the
exposures were taken. The image scale is approximately 11 kilometers (7
miles) 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 Office of Space Science,
Washington, D.C. The Cassini orbiter and its two onboard cameras, were
designed, developed and assembled at JPL. The imaging team is based at
the Space Science Institute, Boulder, Colo.
For more information, about the Cassini-Huygens mission visit,
http://saturn.jpl.nasa.gov and the Cassini imaging team home page,
http://ciclops.org.
