New details on Iapetus are illuminated by reflected light from Saturn in
this revealing Cassini image. Never-before-seen features on the
Saturn-facing part of Iapetus' bright trailing hemisphere are visible for
the first time, including many dark spots, and a sharper view of a dark,
circular structure that was first seen at very low resolution by NASA's
Voyager 1 in 1980. Iapetus diameter is 1,436 kilometers (892 miles).
The image shows mainly the night side of Iapetus; part of the far brighter
sunlit side appears at the right and is overexposed due to the long
integration time of 180 seconds. Despite this long exposure time, almost
no blurring due to the spacecraft's motion is apparent. This technique for
imaging the night side of Iapetus will be used again during a flyby on
Jan. 1, 2005, when Cassini will pass 13 times closer to the icy moon.
The image was taken in visible light with the Cassini spacecraft narrow
angle camera on Oct. 22, 2004, at a distance of 1.6 million kilometers
(994,000 miles) from Iapetus, and from a Sun-Iapetus-spacecraft, or
phase, angle of 161 degrees. The view is centered on 0.4 degrees north
latitude, 317 degrees west longitude on Iapetus. The image scale is 9.4
kilometers (5.8 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.
