Ron
November 8th 04, 09:33 PM
http://www.colorado.edu/news/releases/2004/347.html
Univerity of Colorado at Boulder News Release
Cassini Observations Show Dynamic Dance At Saturn
November 8, 2004
Note to Editors: Esposito will participate in a news briefing Nov. 8 at
the Division of Planetary Sciences meeting in Louisville, Ky. Contents
embargoed until 12:35 p.m. EST Nov. 8.
A University of Colorado at Boulder professor involved with the
Cassini-Huygens mission is reporting an ever-changing vista at the
frontiers of Saturn, featuring wayward moons, colliding meteoroids,
rippling rings and flickering auroras.
Larry Esposito of the Laboratory for Atmospheric and Space Physics said
CU-Boulder's Ultraviolet Imaging Spectrometer, or UVIS, riding on
Cassini is revealing a dynamic dance in the Saturn system. "Instead of a
quiet panorama, UVIS sees rapidly changing phenomena, including
interactions between the rings, moons, radiation belt, solar wind and
the planet Saturn," said Esposito, the principal investigator for the
$12.5 million UVIS instrument.
The instrument has detected oxygen atoms in an immense cloud surrounding
Saturn, the result of moonlets in the ring system colliding, shattering
and releasing ice particles. The ice grains are bathed by Saturn's
radiation belt, liberating the oxygen atoms that reflect sunlight and
which makes them visible to the ultraviolet spectrometer, said Esposito.
A UVIS analysis of Phoebe - a tiny, dark moon about 1-15th the diameter
of Earth's moon -- confirms the suspicions of many space scientists that
it was born elsewhere, most likely in the Kuiper Belt. The Kuiper Belt
is a region beyond Neptune believed to be populated by thousands of
small, icy moons created during the formation of the solar system more
than four billion years ago.
"UVIS sees the absorption signature of water ice on its surface, showing
Phoebe was born in the outer solar system," Esposito said. Exhibiting an
unusual retrograde, or backward, orbit, Phoebe likely was lassoed by
Saturn's powerful gravitational field during the planet's formative
years, he said.
Esposito presented his findings at the 36th annual Division of Planetary
Sciences meeting in Louisville, Ky., Nov. 8 to Nov 12.
The UVIS research team also has noted significant brightening of the
auroras at Saturn's poles as the solar wind periodically ramps up to
speeds of 250 miles, or 400 kilometers, per second, Esposito said.
"Dense puffs of the charged particles from the sun excite the hydrogen
molecules in Saturn's upper atmosphere to glow more brightly."
In addition, UVIS continues to zero in on the fabulous ring system. "At
the time Cassini went into orbit around Saturn, UVIS produced the
highest detail images of Saturn's rings ever made in UV light," he said.
"These images show the amount of water-ice varies in the ring particles'
surfaces."
The variation is caused by the contamination of the rings with meteoric
dust, and by the subsequent transfer of material between the ring
particles from collisions and meteoroid bombardment, Esposito said.
"The fluctuations we see can be explained by the recent destruction of
small moons within the rings and by wave action in the rings that
dredges fresh material onto the surfaces of the ring particles,"
Esposito said. "This indicates that the material in the rings is
continually recycled from rings to moons and back."
The UVIS instrument was used to obtain the highest resolution
observations of the ring particles ever by focusing on the fluctuations
of light from a distant star as it passed behind the rings, he said.
The team also detected a density wave -- a ripple-like feature in the
rings caused by the influence of Saturn's moons -- in the so-called
Cassini Division. The Cassini Division is the gap between the bright A
and B rings of Saturn that are visible from Earth using backyard
telescopes, he said.
"Analysis of such waves determines the size, mass and velocity of the
ring particles," said Esposito.
The UVIS instrument also is showing a bright glow in the upper
atmosphere of Titan, the most intriguing of Saturn's 33 known moons,
which will be targeted by the Cassini-Huygens probe slated for release
by the spacecraft on Christmas Eve. "Observations of Titan show the glow
of nitrogen atoms, molecules and ions energized by electrons striking
the upper atmosphere," he said.
Launched in 1997, the Cassini-Huygens spacecraft achieved Saturn orbit
June 30. During the spacecraft's four-year tour of the Saturn system,
the UVIS team will continue to track the dynamic interactions of the
planet's rings, moons and radiation belts, Esposito said.
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, Calif., manages the Cassini-Huygens mission for NASA's Science
Mission Directorate in Washington, D.C.
Univerity of Colorado at Boulder News Release
Cassini Observations Show Dynamic Dance At Saturn
November 8, 2004
Note to Editors: Esposito will participate in a news briefing Nov. 8 at
the Division of Planetary Sciences meeting in Louisville, Ky. Contents
embargoed until 12:35 p.m. EST Nov. 8.
A University of Colorado at Boulder professor involved with the
Cassini-Huygens mission is reporting an ever-changing vista at the
frontiers of Saturn, featuring wayward moons, colliding meteoroids,
rippling rings and flickering auroras.
Larry Esposito of the Laboratory for Atmospheric and Space Physics said
CU-Boulder's Ultraviolet Imaging Spectrometer, or UVIS, riding on
Cassini is revealing a dynamic dance in the Saturn system. "Instead of a
quiet panorama, UVIS sees rapidly changing phenomena, including
interactions between the rings, moons, radiation belt, solar wind and
the planet Saturn," said Esposito, the principal investigator for the
$12.5 million UVIS instrument.
The instrument has detected oxygen atoms in an immense cloud surrounding
Saturn, the result of moonlets in the ring system colliding, shattering
and releasing ice particles. The ice grains are bathed by Saturn's
radiation belt, liberating the oxygen atoms that reflect sunlight and
which makes them visible to the ultraviolet spectrometer, said Esposito.
A UVIS analysis of Phoebe - a tiny, dark moon about 1-15th the diameter
of Earth's moon -- confirms the suspicions of many space scientists that
it was born elsewhere, most likely in the Kuiper Belt. The Kuiper Belt
is a region beyond Neptune believed to be populated by thousands of
small, icy moons created during the formation of the solar system more
than four billion years ago.
"UVIS sees the absorption signature of water ice on its surface, showing
Phoebe was born in the outer solar system," Esposito said. Exhibiting an
unusual retrograde, or backward, orbit, Phoebe likely was lassoed by
Saturn's powerful gravitational field during the planet's formative
years, he said.
Esposito presented his findings at the 36th annual Division of Planetary
Sciences meeting in Louisville, Ky., Nov. 8 to Nov 12.
The UVIS research team also has noted significant brightening of the
auroras at Saturn's poles as the solar wind periodically ramps up to
speeds of 250 miles, or 400 kilometers, per second, Esposito said.
"Dense puffs of the charged particles from the sun excite the hydrogen
molecules in Saturn's upper atmosphere to glow more brightly."
In addition, UVIS continues to zero in on the fabulous ring system. "At
the time Cassini went into orbit around Saturn, UVIS produced the
highest detail images of Saturn's rings ever made in UV light," he said.
"These images show the amount of water-ice varies in the ring particles'
surfaces."
The variation is caused by the contamination of the rings with meteoric
dust, and by the subsequent transfer of material between the ring
particles from collisions and meteoroid bombardment, Esposito said.
"The fluctuations we see can be explained by the recent destruction of
small moons within the rings and by wave action in the rings that
dredges fresh material onto the surfaces of the ring particles,"
Esposito said. "This indicates that the material in the rings is
continually recycled from rings to moons and back."
The UVIS instrument was used to obtain the highest resolution
observations of the ring particles ever by focusing on the fluctuations
of light from a distant star as it passed behind the rings, he said.
The team also detected a density wave -- a ripple-like feature in the
rings caused by the influence of Saturn's moons -- in the so-called
Cassini Division. The Cassini Division is the gap between the bright A
and B rings of Saturn that are visible from Earth using backyard
telescopes, he said.
"Analysis of such waves determines the size, mass and velocity of the
ring particles," said Esposito.
The UVIS instrument also is showing a bright glow in the upper
atmosphere of Titan, the most intriguing of Saturn's 33 known moons,
which will be targeted by the Cassini-Huygens probe slated for release
by the spacecraft on Christmas Eve. "Observations of Titan show the glow
of nitrogen atoms, molecules and ions energized by electrons striking
the upper atmosphere," he said.
Launched in 1997, the Cassini-Huygens spacecraft achieved Saturn orbit
June 30. During the spacecraft's four-year tour of the Saturn system,
the UVIS team will continue to track the dynamic interactions of the
planet's rings, moons and radiation belts, Esposito said.
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, Calif., manages the Cassini-Huygens mission for NASA's Science
Mission Directorate in Washington, D.C.