Cassini Sees Objects Blazing Trails in Saturn Ring

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Jia-Rui C. Cook 818-354-0850
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Dwayne Brown 202-358-1726
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News release: 2012-111 April 23, 2012

Cassini Sees Objects Blazing Trails in Saturn Ring

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2012-111&cid=release_2012-111

PASADENA, Calif. – Scientists working with images from NASA's Cassini spacecraft
have discovered strange half-mile-sized (kilometer-sized) objects punching through parts
of Saturn's F ring, leaving glittering trails behind them. These trails in the rings, which
scientists are calling "mini-jets," fill in a missing link in our story of the curious behavior
of the F ring. The results will be presented tomorrow at the European Geosciences Union
meeting in Vienna, Austria.

"I think the F ring is Saturn's weirdest ring, and these latest Cassini results go to show
how the F ring is even more dynamic than we ever thought," said Carl Murray, a Cassini
imaging team member based at Queen Mary University of London, England. "These
findings show us that the F ring region is like a bustling zoo of objects from a half mile
[kilometer] to moons like Prometheus a hundred miles [kilometers] in size, creating a
spectacular show."

New images and movies of the mini-jets and other peculiar F ring behavior are available
at http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20120423.html .

Scientists have known that relatively large objects like Prometheus (as long as 92 miles,
or 148 kilometers, across) can create channels, ripples and snowballs in the F ring. But
scientists didn't know what happened to these snowballs after they were created, Murray
said. Some were surely broken up by collisions or tidal forces in their orbit around
Saturn, but now scientists have evidence that some of the smaller ones survive, and their
differing orbits mean they go on to strike through the F ring on their own.

These small objects appear to collide with the F ring at gentle speeds – something on the
order of about 4 mph (2 meters per second). The collisions drag glittering ice particles out
of the F ring with them, leaving a trail typically 20 to 110 miles (40 to 180 kilometers)
long. Murray's group happened to see a tiny trail in an image from Jan. 30, 2009 and
tracked it over eight hours. The long footage confirmed the small object originated in the
F ring, so they went back through the Cassini image catalog to see if the phenomenon
was frequent.

"The F ring has a circumference of 550,000 miles [881,000 kilometers], and these mini-
jets are so tiny they took quite a bit of time and serendipity to find," said Nick Attree, a
Cassini imaging associate at Queen Mary. "We combed through 20,000 images and were
delighted to find 500 examples of these rogues during just the seven years Cassini has
been at Saturn."

In some cases, the objects traveled in packs, creating mini-jets that looked quite exotic,
like the barb of a harpoon. Other new images show grand views of the entire F ring,
showing the swirls and eddies that ripple around the ring from all the different kinds of
objects moving through and around it.

"Beyond just showing us the strange beauty of the F ring, Cassini's studies of this ring
help us understand the activity that occurs when solar systems evolve out of dusty disks
that are similar to, but obviously much grander than, the disk we see around Saturn," said
Linda Spilker, Cassini project scientist based at NASA's Jet Propulsion Laboratory,
Pasadena, Calif. "We can't wait to see what else Cassini will show us in Saturn's rings."

For information about Cassini, visit: http://www.nasa.gov/cassini and
http://saturn.jpl.nasa.gov .

The Cassini-Huygens mission is a cooperative project of NASA, the European Space
Agency, and the Italian Space Agency. NASA's Jet Propulsion Laboratory, Pasadena,
Calif., manages the mission for NASA's Science Mission Directorate, Washington, D.C.
The imaging team is based at the Space Science Institute, Boulder, Colo. JPL is a division
of the California Institute of Technology, Pasadena.

-end-

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