Early images returned from the first detailed reconnaissance of Saturn's
small outer moon, Phoebe, show breathtaking details in the moon's
pockmarked surface that already have imaging scientists puzzling over
the body's history. The images are only a preview of what to expect from
the high resolution images to be examined later today which will show
details about 10 times smaller.
Phoebe has revealed itself to be a rugged, heavily cratered body, with
overlapping craters of varying sizes. This morphology suggests an old
surface. There are apparently many craters smaller than 1 km, indicating
that projectiles probably smaller than 100 meters once pummeled Phoebe.
Whether these objects were cometary or asteroidal in origin, or were the
debris that resulted from impacts on other bodies within the Saturn
system, is hotly debated. There is also variation in surface brightness
across the body.
In the first image (at left) in which Phoebe looks somewhat like a
sideways skull, the large crater near the bottom displays a complex and
rugged interior. The lower right hand part of Phoebe appears to be
covered by bright wispy material.
The second, higher resolution image further reveals the moon's battered
surface, including a crater near the right hand edge with bright rays
that extend outward from its center. This suggests that dark material
coats the outside. Features reminiscent of those seen on the Martian moon
Phobos -- such as linear grooves--are faintly visible in the upper part
of this image. There are suggestions of linear ridges or grooves and of
chains of craters, perhaps radial to a large crater just hidden on the
un-illuminated region in the upper left.
Left to right, the two views were obtained at phase, or
Sun-Phoebe-spacecraft, angles of approximately 86 degrees, and from
distances ranging from 143,068 kilometers (88,918 miles) to 77,441
kilometers (48, 130 miles); for reference, Cassini's closest approach
to Phoebe was approximately 2,068 kilometers (1,285 miles). The image
scale ranges from 0.86 to 0.46 kilometers (0.53 to 0.29 miles) per pixel.
No enhancement of any kind has been performed on the images.
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.