[meteorite-list] Cassini to Make Last Close Flyby of Saturn Moon Dione

[Ron Baalke]

http://www.jpl.nasa.gov/news/news.php?feature=4689

Cassini to Make Last Close Flyby of Saturn Moon Dione
Jet Propulsion Laboratory
August 13, 2015

NASA's Cassini spacecraft will zip past Saturn's moon Dione on Monday, 
Aug. 17 -- the final close flyby of this icy satellite during the spacecraft's 
long mission.

Cassini's closest approach, within 295 miles (474 kilometers) of Dione's 
surface, will occur at 11:33 a.m. PDT (2:33 p.m. EDT). Mission controllers 
expect fresh images to begin arriving on Earth within a couple of days 
following the encounter.

Cassini scientists have a bevy of investigations planned for Dione. Gravity-science 
data from the flyby will improve scientists' knowledge of the moon's internal 
structure and allow comparisons to Saturn's other moons. Cassini has performed 
this sort of gravity science investigation with only a handful of Saturn's 
62 known moons.

During the flyby, Cassini's cameras and spectrometers will get a high-resolution 
peek at Dione's north pole at a resolution of only a few feet (or meters). 
In addition, Cassini's Composite Infrared Spectrometer instrument will 
map areas on the icy moon that have unusual thermal anomalies -- those 
regions are especially good at trapping heat. Meanwhile, the mission's 
Cosmic Dust Analyzer continues its search for dust particles emitted from 
Dione.

This flyby will be the fifth targeted encounter with Dione of Cassini's 
tour at Saturn. Targeted encounters require maneuvers to precisely steer 
the spacecraft toward a desired path above a moon. The spacecraft executed 
a 12-second burn using its thrusters on Aug. 9, which fine-tuned the trajectory 
to enable the upcoming encounter.

Cassini's closest-ever flyby of Dione was in Dec. 2011, at a distance 
of 60 miles (100 kilometers). Those previous close Cassini flybys yielded 
high-resolution views of the bright, wispy terrain on Dione first seen 
during the Voyager mission. Cassini's sharp views revealed the bright 
features to be a system of braided canyons with bright walls. Scientists 
also have been eager to find out if Dione has geologic activity, like 
Saturn's geyser-spouting moon Enceladus, but at a much lower level.

"Dione has been an enigma, giving hints of active geologic processes, 
including a transient atmosphere and evidence of ice volcanoes. But we've 
never found the smoking gun. The fifth flyby of Dione will be our last 
chance," said Bonnie Buratti, a Cassini science team member at NASA's 
Jet Propulsion Laboratory in Pasadena, California.

Cassini has been orbiting Saturn since 2004. After a series of close moon 
flybys in late 2015, the spacecraft will depart Saturn's equatorial plane 
-- where moon flybys occur most frequently -- to begin a year-long setup 
of the mission's daring final year. For its grand finale, Cassini will 
repeatedly dive through the space between Saturn and its rings.

"This will be our last chance to see Dione up close for many years to 
come," said Scott Edgington, Cassini mission deputy project scientist 
at JPL. "Cassini has provided insights into this icy moon's mysteries, 
along with a rich data set and a host of new questions for scientists 
to ponder."

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European 
Space Agency) and the Italian Space Agency. JPL, a division of the California 
Institute of Technology, manages the mission for NASA's Science Mission 
Directorate in Washington.

For more information about Cassini, visit:

http://www.nasa.gov/cassini

http://saturn.jpl.nasa.gov


Media Contact

Preston Dyches
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-7013
preston.dyches at jpl.nasa.gov 

2015-269