From: LARRY KLAES (ljk4_at_msn.com)
Date: Thu Jul 22 2004 - 17:44:52 PDT
----- Original Message -----
From: NASA Jet Propulsion Laboratory<mailto:info_at_jpl.nasa.gov>
To: ljk4_at_msn.com<mailto:ljk4_at_msn.com>
Sent: Thursday, July 15, 2004 3:27 PM
Subject: Cassini Exposes Saturn's Two-Face Moon
MEDIA RELATIONS OFFICE
Carolina Martinez (818) 354-9382
Heidi Finn (720) 974-5859
Image Advisory: 2004-182 July 15, 2004
Cassini Exposes Saturn's Two-Face Moon
The moon with the split personality, Iapetus, presents a perplexing
One hemisphere of the moon is very dark, while the other is very
Iapetus (pronounced eye-APP-eh-tuss) is one of Saturn's 31 known
During Cassini's four-year tour, the spacecraft will continue to image
Iapetus was discovered by the Italian-French astronomer Jean Dominique
This sets Iapetus apart from Saturn's other moons and Jupiter's moons,
One scenario for the outside deposit of material has dark particles
Iapetus is odd in other respects. It is in a moderately inclined
The Cassini-Huygens mission is a cooperative project of NASA, the
For this and other images and information about the Cassini-Huygens
Credit: NASA/JPL/Space Science Institute
-end-
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: Thu Jul 22 2004 - 17:52:25 PDT
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov
Jet Propulsion Laboratory, Pasadena, Calif.
Cassini Imaging Central Laboratory for Operations
Space Science Institute, Boulder, Colo.
appearance in the latest images snapped by the Cassini spacecraft.
bright. Scientists do not yet know the origin of the dark material or
whether or not it is representative of the interior of Iapetus.
moons. Its diameter is about one third that of our own moon at 1,436
kilometers (892 miles). This image was taken in visible light with
the Cassini spacecraft narrow angle camera on July 3, 2004, from a
distance of 3 million kilometers (1.8 million miles) from Iapetus.
The brightness variations in this image are not due to shadowing, they
are real.
Iapetus and conduct two close encounters. One of those encounters,
several years from now, will be at a mere 1,000 kilometers (622
miles).
Cassini in 1672. He correctly deduced that the trailing hemisphere is
composed of highly reflective material, while the leading hemisphere
is strikingly darker.
which tend to be brighter on their leading hemispheres. Voyager
images show that the bright side of Iapetus, which reflects nearly 50
percent of the light it receives, is fairly typical of a heavily
cratered icy satellite. The leading side consists of much darker,
redder material that has a reflectivity of only about 3 to 4 percent.
being ejected from Saturn's little moon Phoebe and drifting inward to
coat Iapetus. One observation lending credence to an internal origin
is the concentration of material on crater floors, which is suggestive
of something filling in the craters.
orbit, one that takes it far above and below the plane in which the
rings and most of the moons orbit. It is less dense than many of the
other satellites, which suggests a higher fraction of ice or possibly
methane or ammonia in its interior.
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.
mission, visit http://saturn.jpl.nasa.gov
and
http://www.nasa.gov/cassini
. Images are also available at the
Cassini imaging team home page, http://ciclops.org
.