FROM: NASA
WASHINGTON -- Scientists working with images from NASA's Cassini
spacecraft have discovered strange, half-mile-sized objects punching
through one of Saturn's rings and leaving glittering trails behind
them. The results will be presented tomorrow at the European
Geosciences Union meeting in Vienna, Austria.
The penetration occurred in the outermost of Saturn's main rings,
called the F ring, which has a circumference of 550,000 miles
(881,000 kilometers). Scientists are calling the trails in the F ring
"mini-jets." Cassini scientists combed through 20,000 images and
found 500 examples of these rogues during the seven years Cassini has
been at Saturn.
"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 at NASA's Jet Propulsion
Laboratory (JPL) in Pasadena, Calif.
Scientists have known relatively large objects can create channels,
ripples and snowballs, or clumps of icy material, in the F ring.
However, scientists did not know what happened to these snowballs
after they were created. Some were broken up by collisions or tidal
forces in their orbit around Saturn. Scientists now have evidence
some of the smaller ones survived, and their differing orbits mean
they go on to strike through the F ring on their own.
"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, U.K. "These findings show
us that the F ring region is like a bustling zoo of objects from a
half-mile (0.8-kilometer) in size to moons like Prometheus a hundred
miles (160.9 kilometers) in size, creating a spectacular show."
These small objects appear to collide with the F ring at gentle speeds
about 4 mph (2 meters per second). The collisions drag glittering ice
particles out of the F ring with them, leaving a trail of 20-110
miles (40-180 kilometers) long.
In some cases, the objects traveled in packs, creating mini-jets that
looked exotic, like the barb of a harpoon. Other new images show
grand views of the entire F ring and the swirls and eddies from the
different kinds of objects moving through and around it.
Saturn's rings are comprised primarily of water ice. The chunks of ice
that make up the main rings spread out 85,000 miles (140,000
kilometers) from the center of Saturn. Scientists believe the rings'
average thickness is approximately 30 feet (10 meters).
The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency and the Italian Space Agency. JPL manages the
mission for NASA's Science Mission Directorate in Washington. The
imaging team is based at the Space Science Institute in Boulder,
Colo.
