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Carolina
Martinez (818) 354-9382
Jet
Propulsion Laboratory, Pasadena, Calif.
Dolores Beasley (202)
358-1753
NASA Headquarters,
Washington
Press
Release: 2005-034
February 24, 2005
NASA's Cassini Spacecraft
Continues Making new Saturn Discoveries
NASA's Cassini spacecraft continues making new and
exciting discoveries. New findings include wandering and rubble-pile
moons; new and clumpy Saturn rings; splintering storms and a dynamic
magnetosphere.
"For the last seven months it has been a nonstop,
science-packed mission. It has been a whirlwind, and already we have many
new results," said Dr. Dennis Matson, Cassini project scientist at NASA's
Jet Propulsion Laboratory, Pasadena, Calif.
Weak, linear density waves caused in Saturn's rings
by the small moons Atlas and Pan have yielded more reliable calculations
of their masses. The masses imply the moons are very porous, perhaps
constructed like rubble piles. They are similar to the moons that shepherd
Saturn's F ring, Prometheus and Pandora.
Another discovery was a tiny moon, about 5 kilometers
(3 miles) across, recently named Polydeuces. Polydeuces is a companion, or
�Trojan� moon of Dione. Trojan moons are found near gravitationally stable
points ahead or behind a larger moon. Saturn is the only planet known to
have moons with companion Trojan moons.
The new findings, published in this week�s edition of
the journal Science, include refinements in the orbits of several of
Saturn's small satellites. One intriguing result is the eccentric and
slightly inclined orbit of Pan in Saturn's A ring. The orbit's shape is
significant, as it indicates the type of interaction the moon has with the
ring material surrounding it. If Pan's orbit remains eccentric due to this
interaction, then planets growing in a disc of material surrounding a star
may also have eccentric orbits. This may help explain the eccentric paths
of planets orbiting other stars.
Several faint Saturn rings have been discovered in
Cassini images. Some lie in various gaps in the rings and may indicate the
presence of tiny embedded moons acting as shepherds. Several of the rings
are kinked, likely evidence of nearby moons.
Scientists also found Saturn's winds change with
altitude, and small storms emerge out of large ones. For the first time,
Cassini images captured possible evidence of processes that may maintain
the winds on Saturn. The observations offer a glimpse into the process
which transfers energy by convection from Saturn's interior to help
sustain strong winds.
Other results improve the understanding of Saturn's
complex magnetic environment.
�Saturn�s magnetosphere is truly unique. It�s dynamically similar to
Jupiter�s, but in places it chemically resembles water-based plasmas
surrounding comets,� said Dr. David Young. Young is Cassini principal
investigator for the plasma spectrometer instrument from the Southwest
Research Institute, San Antonio.
Another surprising find was made by the ion and
neutral mass spectrometer instrument, which measured molecular oxygen ions
above Saturn's ring plane. "This is at first surprising since the rings
are made of water ice," said Dr. Hunter Waite, principal investigator for
the spectrometer from the University of Michigan, Ann Arbor. "This may
have important consequences for the identification of spectral features to
use in the search for life on extrasolar terrestrial planet
systems.�
The abundance of molecular oxygen on Earth is
uniquely tied to biology. But these new measurements at Saturn suggest
there are lifeless processes associated with cold icy surfaces that may
produce an independent pathway for the formation of molecular oxygen in
atmospheres.
For
images and information on the Cassini mission visit http://saturn.jpl.nasa.gov
and http://www.nasa.gov/cassini
.
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 Science Mission Directorate,
Washington, D.C. The Cassini orbiter was designed, developed and assembled
at JPL.
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