Andrew Yee
September 7th 05, 03:53 AM
Office of News Services
University of Colorado-Boulder
Boulder, Colorado
Contact:
Larry Esposito, (303) 492-5990
Joshua Colwell, (303) 492-6805
Jim Scott (303) 492-3114
Sept. 5, 2005
New Observations Show Dynamic Particle Clumps In Saturn's A Ring
New observations from the Cassini spacecraft now at Saturn indicate the
particles comprising one of its most prominent rings are trapped in
ever-changing clusters of debris that are regularly torn apart and
reassembled by gravitational forces from the planet.
According to University of Colorado at Boulder Professor Larry Esposito of
the Laboratory for Atmospheric and Space Physics, particle clusters in the
outermost main ring, the A ring, range from the size of sedans to moving
vans and are far too small to be photographed by the spacecraft cameras.
The size and behavior of the clusters were deduced by a research team
observing the flickering starlight as the ring passed in front of several
stars in a process known as stellar occultation, he said.
This is the first time scientists have been able to measure the size,
orientation and spacing of these particle clumps in Saturn's rings, he
said. Esposito is the science team leader for the Ultra Violet Imaging
Spectrograph, or UVIS, a $12.5 million instrument designed and built at
CU-Boulder that is riding on Cassini.
CU-Boulder planetary scientist Joshua Colwell, UVIS science team member,
said researchers believe Saturn's ring particles are made up of ice, dust
and rock, and range in size from dust grains to mountains. The new
observations of the particle clusters indicate the A ring is primarily
empty space.
"The spacing between the clumps as determined by UVIS data is greater than
the widths of the clumps themselves," Colwell said. "If we could get close
enough to the rings, these clumps would appear as short, flattened strands
of spiral arms with very few particles between them."
Colwell participated in a press briefing on new Cassini-Huygens
observations at the 37th Annual Meeting of the Division for Planetary
Sciences meeting held Sept. 4 to Sept. 9 in Cambridge, England.
Bound to each other by their own gravity, the clumps are periodically torn
apart by the gravitational tides of Saturn, said Colwell. He likened the
process to a handful of marbles placed in orbit around a beach ball. The
marbles closest to the ball would orbit more quickly and drift from the
pack before reorganizing themselves into new, orbiting clumps.
The individual clusters were largest near the middle of the ring and
became smaller toward the edges of the ring, the team reported. The
cluster cores range in size from two meters to 13 meters, or 7 feet to 43
feet. There are no indications yet that similar clumps exist in Saturn's
other rings, confirming predictions made by the team from computer
simulations.
The UVIS team also detected a tenuous atmosphere on Saturn's tiny moon
Enceladus made of water vapor, said Esposito. The researchers detected no
free-floating hydrogen or oxygen atoms, implying the water was recently
released -- perhaps from a local fissure near the moon's south pole -- and
was escaping from its surface. Enceladus is only about 310 miles, or 500
kilometers, in diameter.
When combined with Cassini images and results from other spectrometers
onboard the spacecraft, the new Enceladus observations indicate water and
grains of ice are being spewed from the moon's surface much in the manner
of gaseous jets that have been observed erupting on the surface of comets,
Esposito said. "The rate of water released is sufficient to provide the
neutral oxygen discovered by UVIS around Saturn last year and to re-supply
Saturn's E ring."
In July, the UVIS team released new images from the mission depicting
emissions near Saturn's poles that resemble Earth's northern lights. The
image can be viewed at:
http://www.colorado.edu/news/releases/2005/290.html
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 in
Washington, D.C.
The Cassini orbiter was designed, developed and assembled at JPL. The
ultraviolet imaging spectrograph was built, and the team is based, at the
University of Colorado at Boulder.
For more information about the Cassini-Huygens mission visit
http://saturn.jpl.nasa.gov
The ultraviolet imaging spectrograph team home page is at
http://lasp.colorado.edu/cassini
Note to Editors: Contents embargoed until 3:45 a.m. EDT on Monday, Sept 5.
A graphic of the ring clusters is available at
http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=1707
University of Colorado-Boulder
Boulder, Colorado
Contact:
Larry Esposito, (303) 492-5990
Joshua Colwell, (303) 492-6805
Jim Scott (303) 492-3114
Sept. 5, 2005
New Observations Show Dynamic Particle Clumps In Saturn's A Ring
New observations from the Cassini spacecraft now at Saturn indicate the
particles comprising one of its most prominent rings are trapped in
ever-changing clusters of debris that are regularly torn apart and
reassembled by gravitational forces from the planet.
According to University of Colorado at Boulder Professor Larry Esposito of
the Laboratory for Atmospheric and Space Physics, particle clusters in the
outermost main ring, the A ring, range from the size of sedans to moving
vans and are far too small to be photographed by the spacecraft cameras.
The size and behavior of the clusters were deduced by a research team
observing the flickering starlight as the ring passed in front of several
stars in a process known as stellar occultation, he said.
This is the first time scientists have been able to measure the size,
orientation and spacing of these particle clumps in Saturn's rings, he
said. Esposito is the science team leader for the Ultra Violet Imaging
Spectrograph, or UVIS, a $12.5 million instrument designed and built at
CU-Boulder that is riding on Cassini.
CU-Boulder planetary scientist Joshua Colwell, UVIS science team member,
said researchers believe Saturn's ring particles are made up of ice, dust
and rock, and range in size from dust grains to mountains. The new
observations of the particle clusters indicate the A ring is primarily
empty space.
"The spacing between the clumps as determined by UVIS data is greater than
the widths of the clumps themselves," Colwell said. "If we could get close
enough to the rings, these clumps would appear as short, flattened strands
of spiral arms with very few particles between them."
Colwell participated in a press briefing on new Cassini-Huygens
observations at the 37th Annual Meeting of the Division for Planetary
Sciences meeting held Sept. 4 to Sept. 9 in Cambridge, England.
Bound to each other by their own gravity, the clumps are periodically torn
apart by the gravitational tides of Saturn, said Colwell. He likened the
process to a handful of marbles placed in orbit around a beach ball. The
marbles closest to the ball would orbit more quickly and drift from the
pack before reorganizing themselves into new, orbiting clumps.
The individual clusters were largest near the middle of the ring and
became smaller toward the edges of the ring, the team reported. The
cluster cores range in size from two meters to 13 meters, or 7 feet to 43
feet. There are no indications yet that similar clumps exist in Saturn's
other rings, confirming predictions made by the team from computer
simulations.
The UVIS team also detected a tenuous atmosphere on Saturn's tiny moon
Enceladus made of water vapor, said Esposito. The researchers detected no
free-floating hydrogen or oxygen atoms, implying the water was recently
released -- perhaps from a local fissure near the moon's south pole -- and
was escaping from its surface. Enceladus is only about 310 miles, or 500
kilometers, in diameter.
When combined with Cassini images and results from other spectrometers
onboard the spacecraft, the new Enceladus observations indicate water and
grains of ice are being spewed from the moon's surface much in the manner
of gaseous jets that have been observed erupting on the surface of comets,
Esposito said. "The rate of water released is sufficient to provide the
neutral oxygen discovered by UVIS around Saturn last year and to re-supply
Saturn's E ring."
In July, the UVIS team released new images from the mission depicting
emissions near Saturn's poles that resemble Earth's northern lights. The
image can be viewed at:
http://www.colorado.edu/news/releases/2005/290.html
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 in
Washington, D.C.
The Cassini orbiter was designed, developed and assembled at JPL. The
ultraviolet imaging spectrograph was built, and the team is based, at the
University of Colorado at Boulder.
For more information about the Cassini-Huygens mission visit
http://saturn.jpl.nasa.gov
The ultraviolet imaging spectrograph team home page is at
http://lasp.colorado.edu/cassini
Note to Editors: Contents embargoed until 3:45 a.m. EDT on Monday, Sept 5.
A graphic of the ring clusters is available at
http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=1707