From: LARRY KLAES (ljk4_at_msn.com)
Date: Thu Oct 25 2007 - 06:16:26 PDT
>From: Lynn Cominsky <lynnc_at_universe.sonoma.edu>
>To: lynnc_at_universe.sonoma.edu
>Subject: CU-BOULDER: FIRST-KNOWN BELT OF MOONLETS IN SATURN RINGS
>Date: Tue, 23 Oct 2007 15:26:42 -0700
>
>THE FOLLOWING RELEASE WAS RECEIVED FROM THE UNIVERSITY OF COLORADO,
>IN BOULDER, AND IS FORWARDED FOR YOUR INFORMATION.
>(FORWARDING DOES NOT IMPLY ENDORSEMENT BY THE AMERICAN
>ASTRONOMICAL SOCIETY.) Lynn Cominsky, American Astronomical Society
>lynnc_at_universe.sonoma.edu 1-707-664-2655
>
>**Please note the strict embargo for 1:00 PM EDT, Wednesday, October 24,
>2007, consistent with publication in Nature. LRC**
>
>Contact: Miodrag Sremcevic (303) 492-3395
> Miodrag.Sremcevic_at_lasp.colorado.edu
> Nicole Albers, (303) 735-4459
> Nicole.albers_at_lasp.colorado.edu
>
>PIO Contact: Jim Scott (303) 492-3114
> Jim.Scott_at_Colorado.EDU
>
>Oct. 24, 2007
>
>NEW CU-BOULDER STUDY DETECTS FIRST-KNOWN BELT OF MOONLETS IN SATURN RINGS
>
>Editor's note: Contents embargoed until 1 p.m. EDT on Wednesday,
>Oct. 24.
>
>A narrow belt harboring moonlets as large as football stadiums
>discovered in Saturn's outermost ring probably resulted when a larger
>moon was shattered by a wayward asteroid or comet eons ago, according
>to a University of Colorado at Boulder study.
>
>Images taken by a camera onboard the NASA Cassini spacecraft revealed
>a series of eight propeller-shaped "wakes" in a thin belt of the
>outermost "A" ring, indicating the presence of corresponding
>moonlets, said CU-Boulder Research Associate Miodrag Sremcevic, lead
>author of the study published in the Oct. 25 issue of Nature. The
>propeller wakes highlight tiny areas of the belt where ring material
>has been perturbed by the gravitational forces caused by individual
>moonlets, Sremcevic said.
>
>The team calculated that there likely are thousands of moonlets
>ranging in size from semi-trailers to sports arenas embedded in the
>"A" ring's thin moonlet belt that circles the planet. At about 2,000
>miles across, the belt of moonlets is only about 1/80th the diameter
>of Saturn's total ring system, which at roughly 155,000 miles across
>would stretch about two-thirds of the way from Earth to the moon.
>
>"This is the first evidence of a moonlet belt in any of Saturn's
>rings," said Sremcevic of CU-Boulder's Laboratory for Atmospheric and
>Space Physics. "We have firmly established these moonlets exist in a
>relatively narrow region of the "A" ring, and the evidence indicates
>they are remnants of a larger moon that was shattered by a meteoroid
>or comet."
>
>Co-authors of the Nature study include Juergen Schmidt, Martin Seiss
>and Frank Spahn of the University of Potsdam in Germany, Heikko Salo
>of the University of Oulu in Finland, and Nicole Albers of CU-
>Boulder's LASP. The images were taken by the Narrow Angle Camera
>onboard the NASA Cassini spacecraft, which was launched in 1997 and
>has been orbiting the Saturn system since July 2004.
>
>Each propeller feature is about 10 miles long, said Sremcevic, who
>with Spahn first predicted the existence of such propellers in
>Saturn's rings as an undergraduate at the University of Belgrade in
>2000. While four propellers were discovered in the "A" ring in 2006
>by a team led by Cornell University, Sremcevic and his colleagues
>looked at a much larger image sequence, allowing them to extrapolate
>statistically and confirm the presence of thousands of small objects
>in the "A" ring's moonlet belt.
>
>The moonlets may be the result of the break-up of a ring-moon similar
>to Pan -- Saturn's innermost 20-mile diameter moon -- that was
>smashed by a comet or meteor, the team concluded. The team
>calculated the mass of the unseen moonlets in the belt greater than
>50 feet in diameter to arrive at the estimated size of the moon
>involved in the collision creating the belt.
>
> The finding supports the theory that Saturn's rings initially were
>created in a "collisional cascade" of ring debris begun by a
>catastrophic break-up of an even larger moon in the Saturn system
>first proposed by CU-Boulder planetary scientists Larry Esposito and
>Joshua Colwell in 1987. The moonlets in the newly discovered belt
>may have formed after Saturn's rings already were in place, which
>planetary scientists speculate could have been hundreds of millions
>or even billions of years ago.
>
>"It seems unlikely that moonlets are remainders of a single
>catastrophic event that created the whole ring system, because in
>this case a uniform distribution would emerge," the researchers wrote
>in Nature. "Instead, the moonlet belt is compatible with a more
>recent body orbiting in the A ring."
>
>Esposito, who was not involved in the study, said the propellers
>"show a striking demonstration of the lingering effects of the
>gravity from these small, embedded moonlets." Esposito is the chief
>scientist on the NASA Cassini mission's $12.5 million Ultra-Violet
>Imaging Spectrograph designed and built at LASP.
>
>Sremcevic said the discovery of the moonlet belt is another piece in
>the puzzle regarding the formation and evolution of Saturn's rings.
>"We believe future studies of ring evolution will need to incorporate
>the findings and implications from this study."
>
>The NASA Cassini mission, formerly called 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 NASA Cassini mission for NASA's Science Mission
>Directorate in Washington, D.C.
>
>For more information about NASA Cassini-Huygens visit http://
>saturn.jpl.nasa.gov. To listen to a podcast of Sremcevic describing
>his findings visit: http://www.colorado.edu/news/podcasts/.
>
>
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