Saturn System driven by ice

December 16, 2004

Ice particles are key players in the ever-changing panorama at Saturn, according to a new study led by a University of Colorado at Boulder professor using an instrument on the Cassini-Huygens spacecraft now at the ringed planet.
Larry Esposito of the Laboratory for Atmospheric and Space Physics said data from the Ultraviolet Imaging Spectrometer, or UVIS, indicates much of Saturn's system is filled with ice, as well as atoms derived from water. Esposito is the principal investigator for the $12.5 million UVIS instrument riding on the craft.

Esposito said hydrogen and oxygen atoms are widely distributed in the planetary system, which extends millions of miles outward from Saturn. Cassini researchers are seeing large fluctuations in the amount of oxygen in the Saturn system, he said.

"A possible explanation for the fluctuation in oxygen is that small, unseen icy moons have been colliding with Saturn's E ring," said Esposito. "The collisions may have produced small grains of ice, which yielded oxygen atoms when struck by energetic, charged particles in Saturn's magnetosphere. UVIS is able to identify these glowing atoms."

A paper on the subject authored by Esposito and colleagues appears in the Dec. 16 issue of Science Express, the online version of Science magazine. Esposito also will give a presentation on the new results from the Cassini-Huygens mission at the Fall Meeting of the American Geophysical Union, being held this week through Friday in San Francisco.

Saturn's ring particles may have formed originally from pure ice, Esposito said. But they have since been subjected to continual bombardment by meteorites, which has contaminated the ice and caused the rings to darken.

Over time, incessant meteorite bombardment has likely spread the dirty material resulting from the collisions widely among the ring particles, he said. But instead of uniformly dark rings, the UVIS instrument is recording "radial variations" that show brighter and darker bands in the individual rings.

"The evidence indicates that in the last 10 million to 100 million years, fresh material probably was added to the ring system," he said. The research team proposed that such "renewal events" are from the fragmentation of small moons, each probably about 20 kilometers (12 miles) across.

"The interiors of the tiny moonlets, which have been shielded from contamination by the continual collisions with each other, are the source of purer water ice," he said. "Both the oxygen fluctuation and the spectral variation in Saturn's rings support a model of ring history in which small moons are continually destroyed to produce new rings."

The ice grains released by the continual moonlet collisions are bathed by Saturn's radiation belt, liberating the oxygen atoms that are seen by UVIS in the ultraviolet as they reflect sunlight in the immense cloud surrounding Saturn, said Esposito.

Other authors on the Science Express paper include LASP's Joshua Colwell, Kristopher Larsen, William McClintock and Ian Stewart. Researchers from the University of Southern California, NASA's Jet Propulsion Laboratory, Central Arizona University, the California Institute of Technology and the Max Planck Institute and Stuttgart University in Germany also co-authored the paper.

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.

JPL designed, developed and assembled the Cassini orbiter, ESA built and manage the development of the Huygens probe and the Italian Space Agency provided electronic elements for the some of the spacecraft and instruments.

Source: University of Colorado at Boulder

Explore further: Signs of Europa plumes remain elusive in search of Cassini data

Related Stories

A fizzy ocean on Enceladus

January 27, 2011

For years researchers have been debating whether Enceladus, a tiny moon floating just outside Saturn's rings, is home to a vast underground ocean. Is it wet--or not? Now, new evidence is tipping the scales. Not only does ...

New Cassini Images Show "Northern Lights" Of Saturn

August 4, 2005

New images of Saturn obtained by a University of Colorado at Boulder-led team on June 21 using an instrument on the Cassini spacecraft show auroral emissions at its poles similar to Earth's Northern Lights.

Recommended for you

How bees naturally vaccinate their babies

July 31, 2015

When it comes to vaccinating their babies, bees don't have a choice—they naturally immunize their offspring against specific diseases found in their environments. And now for the first time, scientists have discovered how ...

Image: Hubble sees a dying star's final moments

July 31, 2015

A dying star's final moments are captured in this image from the NASA/ESA Hubble Space Telescope. The death throes of this star may only last mere moments on a cosmological timescale, but this star's demise is still quite ...

Earth flyby of 'space peanut' captured in new video

July 31, 2015

NASA scientists have used two giant, Earth-based radio telescopes to bounce radar signals off a passing asteroid and produce images of the peanut-shaped body as it approached close to Earth this past weekend.

Exoplanets 20/20: Looking back to the future

July 31, 2015

Geoff Marcy remembers the hair standing up on the back of his neck. Paul Butler remembers being dead tired. The two men had just made history: the first confirmation of a planet orbiting another star.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.