Cassini Flyby of Enceladus to Offer Insight into Solar System History

Oct. 6, 2008

Contact:
Nicole Casal Moore
1-734-647-1838 or 1-734-647-7087
ncmoore@xxxxxxxxx

CASSINI FLYBY OF SATURN MOON TO OFFER INSIGHT INTO SOLAR SYSTEM
HISTORY

ANN ARBOR, Mich.--- NASA's Cassini spacecraft is scheduled to fly
within 16 miles of Saturn's moon Enceladus on Oct. 9 and measure
molecules in its space environment that could give insight into the
history of the solar system.

"This encounter will potentially have far-reaching implications for
understanding how the solar system was formed and how it evolved,"
said professor Tamas Gombosi, chair of the University of Michigan
Department of Atmospheric, Oceanic and Space Sciences.
Gombosi is the interdisciplinary scientist for magnetosphere and
plasma science on the Cassini mission. His role is to coordinate
studies that involve multiple plasma instruments on the spacecraft.

Enceladus is Saturn's sixth-largest moon, orbiting within the planet's
outermost ring. It is approximately 313 miles in diameter.

In this flyby, Cassini will be close enough to Enceladus to identify
individual molecules in the moon's space environment, including ions
and isotopes. An ion is a charged particle, or a version of an element
that has lost or gained negatively charged electrons. An isotope is a
version of an element that has in its nucleus the typical protons for
that element, but a different number of neutrons, thus exhibiting a
different atomic weight.

The atoms around Enceladus are expected to hold clues to the past
because they come from interior regions that have changed little since
the moon was formed. Geysers near the moon's south pole spew water and
other molecules from the satellite's interior. Because of Enceladus'
weak gravity and low atmospheric pressure, the water and gas molecules
waft off to space.

The encounter will contribute to scientists' understanding of how
particles become charged and energized in Saturn's magnetosphere.
Also, when Cassini identifies the different isotopes in the space
around the moon, it will help scientists discern the temperatures at
various stages in Enceladus' formation eons ago.

Cassini discovered the geysers on Enceladus in 2005. Scientists
believe that there could be a liquid ocean beneath the moon's surface.
They also detected organic molecules at the moon in March. Organic
molecules have carbon-hydrogen bonds, and are found in living
organisms, and in comets.

"The mission as a whole is expected to bring central pieces of the
solar system evolution puzzle into place," Gombosi said. "This
encounter is expected to provide some of those puzzle pieces."

This will be Cassini's fifth encounter with Enceladus. A sixth
encounter, during which it will approach within 122 miles of the moon,
is scheduled for Oct. 31. Four more flybys are planned in the next two
years of Cassini's extended mission, the Cassini Equinox Mission.

The Cassini-Huygens spacecraft was launched in 1997 and reached Saturn
to study the planet and its moons in 2004. It is a cooperative project
of NASA, the European Space Agency and the Italian Space Agency. The
Jet Propulsion Laboratory (JPL), a division of the California
Institute of Technology in Pasadena, manages the mission for NASA's
Science Mission Directorate, Washington, D.C. The Cassini orbiter was
designed, developed and assembled at JPL.

Gombosi is also the Rollin M. Gerstacker Professor of Engineering, and
a professor in the Department of Aerospace Engineering.

For more information:
Tamas Gombosi: http://www-personal.umich.edu/~tamas/
Cassini mission: http://saturn.jpl.nasa.gov/home/index.cfm

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