[meteorite-list] Cassini Observes Meteors Colliding With Saturn's Rings

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 25 Apr 2013 12:34:12 -0700 (PDT)
Message-ID: <201304251934.r3PJYCe5001096_at_zagami.jpl.nasa.gov>

April 25, 2013

Dwayne Brown
Headquarters, Washington
202-358-1726
dwayne.c.brown at nasa.gov

Jia-Rui C. Cook
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-0850
jccook at jpl.nasa.gov

RELEASE: 13-120

NASA PROBE OBSERVES METEORS COLLIDING WITH SATURN'S RINGS

WASHINGTON -- NASA's Cassini spacecraft has provided the first direct
evidence of small meteoroids breaking into streams of rubble and
crashing into Saturn's rings.

These observations make Saturn's rings the only location besides
Earth, the moon, and Jupiter where scientists and amateur astronomers
have been able to observe impacts as they occur. Studying the impact
rate of meteoroids from outside the Saturn system helps scientists
understand how different planet systems in the solar system formed.

Our solar system is full of small, speeding objects. Planetary bodies
frequently are pummeled by them. The meteoroids at Saturn range from
about one-half inch to several yards (1 centimeter to several meters)
in size. It took scientists years to distinguish tracks left by nine
meteoroids in 2005, 2009 and 2012.

Details of the observations appear in a paper in the Thursday edition
of Science.

Results from Cassini already have shown Saturn's rings act as very
effective detectors of many kinds of surrounding phenomena, including
the interior structure of the planet and the orbits of its moons. For
example, a subtle but extensive corrugation that ripples 12,000 miles
(19,000 kilometers) across the innermost rings tells of a very large
meteoroid impact in 1983.

"These new results imply the current-day impact rates for small
particles at Saturn are about the same as those at Earth-- two very
different neighborhoods in our solar system, and this is exciting to
see," said Linda Spilker, Cassini project scientist at NASA's Jet
Propulsion Laboratory (JPL) in Pasadena, Calif. "It took Saturn's
rings acting like a giant meteoroid detector -- 100 times the surface
area of the Earth -- and Cassini's long-term tour of the Saturn
system to address this question."

The Saturnian equinox in summer 2009 was an especially good time to
see the debris left by meteoroid impacts. The very shallow sun angle
on the rings caused the clouds of debris to look bright against the
darkened rings in pictures from Cassini's imaging science subsystem.

"We knew these little impacts were constantly occurring, but we didn't
know how big or how frequent they might be, and we didn't necessarily
expect them to take the form of spectacular shearing clouds," said
Matt Tiscareno, lead author of the paper and a Cassini participating
scientist at Cornell University in Ithaca, N.Y. "The sunlight shining
edge-on to the rings at the Saturnian equinox acted like an
anti-cloaking device, so these usually invisible features became
plain to see."

Tiscareno and his colleagues now think meteoroids of this size
probably break up on a first encounter with the rings, creating
smaller, slower pieces that then enter into orbit around Saturn. The
impact into the rings of these secondary meteoroid bits kicks up the
clouds. The tiny particles forming these clouds have a range of
orbital speeds around Saturn. The clouds they form soon are pulled
into diagonal, extended bright streaks.

"Saturn's rings are unusually bright and clean, leading some to
suggest that the rings are actually much younger than Saturn," said
Jeff Cuzzi, a co-author of the paper and a Cassini interdisciplinary
scientist specializing in planetary rings and dust at NASA's Ames
Research Center in Moffett Field, Calif. "To assess this dramatic
claim, we must know more about the rate at which outside material is
bombarding the rings. This latest analysis helps fill in that story
with detection of impactors of a size that we weren't previously able
to detect directly."

The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency and the Italian Space Agency. JPL manages the
Cassini-Huygens mission for NASA's Science Mission Directorate in
Washington. JPL designed, developed and assembled the Cassini orbiter
and its two onboard cameras. The imaging team consists of scientists
from the United States, England, France and Germany. The imaging
operations center is based at the Space Science Institute in Boulder,
Colo.

For images of the impacts and information about Cassini, visit:

http://www.nasa.gov/cassini
        
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Received on Thu 25 Apr 2013 03:34:12 PM PDT