[meteorite-list] Scientists Discover New Ring and Other Features at Saturn

[Ron Baalke]

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov

Carolina Martinez 818-354-9382
Jet Propulsion Laboratory, Pasadena, Calif.

Preston Dyches 720-974-5859
Cassini Imaging Central Laboratory for Operations 
Space Science Institute, Boulder, Colo.
         					
News Release: 2006-110   		September 19, 2006

Scientists Discover New Ring and Other Features at Saturn

Saturn sports a new ring in an image taken by NASA's Cassini 
spacecraft on Sunday, Sept. 17, during a one-of-a-kind 
observation.

Other spectacular sights captured by Cassini's cameras 
include wispy fingers of icy material stretching out tens of 
thousands of kilometers from the active moon, Enceladus, 
and a cameo color appearance by planet Earth.

The images were obtained during the longest solar occultation 
of Cassini's four-year mission.  During a solar occultation, 
the sun passes directly behind Saturn, and Cassini lies in 
the shadow of Saturn while the rings are brilliantly backlit. 
Usually, an occultation lasts only about an hour, but this 
time it was a 12-hour marathon.  

Sunday's occultation allowed Cassini to map the presence of 
microscopic particles that are not normally visible across 
the ring system.  As a result, Cassini saw the entire inner 
Saturnian system in a new light.

The new ring is a tenuous feature, visible outside the 
brighter main rings of Saturn and inside the G and E rings, 
and coincides with the orbits of Saturn's moons Janus and 
Epimetheus. Scientists expected that meteoroid impacts on 
Janus and Epimetheus might kick particles off the moons' 
surfaces and inject them into Saturn orbit, but they were 
surprised that a well-defined ring structure exists at this 
location.

Saturn's extensive, diffuse E ring, the outermost ring, had 
previously been imaged one small section at a time.  The 
12-hour marathon enabled scientists to see the entire 
structure in one view.  The moon Enceladus is seen sweeping 
through the E ring, extending wispy, fingerlike projections 
into the ring.  These very likely consist of tiny ice 
particles being ejected from Enceladus' south polar geysers, 
and entering the E-ring. 

"Both the new ring and the unexpected structures in the E 
ring should provide us with important insights into how moons 
can both release small particles and sculpt their local 
environments," said Matt Hedman, a research associate working 
with team member Joseph Burns, an expert in diffuse rings, at 
Cornell University in Ithaca, N.Y.

In the latest observations, scientists once again see the 
bright ghost-like spokes -- transient, dusty, radial 
structures -- streaking across the middle of Saturn's main 
rings.  Capping off the new batch of observations, Cassini 
cast its powerful eyes in our direction and captured Earth, a 
pale blue orb, and a faint suggestion of our moon.  Not since 
NASA's Voyager 1 spacecraft saw Earth as a pale blue dot from 
beyond the orbit of Neptune has Earth been imaged in color 
from the outer solar system. 
 
"Nothing has greater power to alter our perspective of 
ourselves and our place in the cosmos than these images of 
Earth we collect from faraway places like Saturn," said 
Carolyn Porco, Cassini imaging team leader at the Space 
Science Institute, Boulder, Colo.  Porco was one of the 
Voyager imaging scientists involved in taking the Voyager 
`Pale Blue Dot' image. "In the end, the ever-widening view of 
our own little planet against the immensity of space is 
perhaps the greatest legacy of all our interplanetary 
travels."

In the coming weeks, several science teams will analyze data 
collected by Cassini's other instruments during this rare 
occultation event.  The data will help scientists better 
understand the relationship between the rings and moons, and 
will give mission planners a clearer picture of ring hazards 
to avoid during future ring crossings.  

Images of the new ring, the E-ring, Enceladus and Earth are 
available at: http://www.nasa.gov/cassini , 
http://saturn.jpl.nasa.gov and http://ciclops.org .

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, 
Washington. The Cassini orbiter and its two onboard cameras 
were designed, developed and assembled at JPL. The imaging 
team is based at the Space Science Institute, Boulder, Colo.

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