[AstroNet] NASA Extends Cassini's Grand Tour of Saturn

[Maciej Soltynski]

April 15, 2008

RELEASE: 08-098

NASA EXTENDS CASSINI'S GRAND TOUR OF SATURN

PASADENA, Calif. -- NASA is extending the international 
Cassini-Huygens mission by two years. The historic spacecraft's 
stunning discoveries and images have revolutionized our knowledge of 
Saturn and its moons.

Cassini's mission originally had been scheduled to end in July 2008. 
The newly-announced two-year extension will include 60 additional 
orbits of Saturn and more flybys of its exotic moons. These will 
include 26 flybys of Titan, seven of Enceladus, and one each of 
Dione, Rhea and Helene. The extension also includes studies of 
Saturn's rings, its complex magnetosphere, and the planet itself. 

"This extension is not only exciting for the science community, but 
for the world to continue to share in unlocking Saturn's secrets," 
said Jim Green, director, Planetary Science Division, NASA 
Headquarters, Washington. "New discoveries are the hallmarks of its 
success, along with the breathtaking images beamed back to Earth that 
are simply mesmerizing."

"The spacecraft is performing exceptionally well and the team is 
highly motivated, so we're excited at the prospect of another two 
years," said Bob Mitchell, Cassini program manager at NASA's Jet 
Propulsion Laboratory in Pasadena, Calif.

Based on findings from Cassini, scientists think liquid water may be 
just beneath the surface of Saturn's moon, Enceladus. That's why the 
small moon, only one-tenth the size of Titan and one-seventh the size 
of Earth's moon, is one of the highest-priority targets for the 
extended mission. 

Cassini discovered geysers of water-ice jetting from the Enceladus' 
surface. The geysers, which shoot out at a distance three times the 
diameter of Enceladus, feed particles into Saturn's most expansive 
ring. In the extended mission, the spacecraft may come as close as 15 
miles from the moon's surface.

Cassini's observations of Saturn's largest moon, Titan, have given 
scientists a glimpse of what Earth might have been like before life 
evolved. They now believe Titan possesses many parallels to Earth, 
including lakes, rivers, channels, dunes, rain, snow, clouds, 
mountains and possibly volcanoes.

"When we designed the original tour, we really did not know what we 
would find, especially at Enceladus and Titan," said Dennis Matson, 
the JPL Cassini project scientist. "This extended tour is responding 
to these new discoveries and giving us a chance to look for more." 

Unlike Earth, Titan's lakes, rivers and rain are composed of methane 
and ethane, and temperatures reach a chilly minus 290 degrees 
Fahrenheit. Although Titan's dense atmosphere limits viewing the 
surface, Cassini's high-resolution radar coverage and imaging by the 
infrared spectrometer have given scientists a better look.

Other activities for Cassini scientists will include monitoring 
seasons on Titan and Saturn, observing unique ring events, such as 
the 2009 equinox when the sun will be in the plane of the rings, and 
exploring new places within Saturn's magnetosphere.

Cassini has returned a daily stream of data from Saturn's system for 
almost four years. Its travel scrapbook includes nearly 140,000 
images and information gathered during 62 revolutions around Saturn, 
43 flybys of Titan and 12 close flybys of the icy moons.

More than 10 years after launch and almost four years after entering 
into orbit around Saturn, Cassini is a healthy and robust spacecraft. 
Three of its science instruments have minor ailments, but the impact 
on science-gathering is minimal. The spacecraft will have enough 
propellant left after the extended mission to potentially allow a 
third phase of operations. Data from the extended mission could lay 
the groundwork for possible new missions to Titan and Enceladus.

Cassini launched Oct. 15, 1997, from Cape Canaveral, Fla., on a 
seven-year journey to Saturn, traversing 2.2 billion miles. It is one 
of the most scientifically capable spacecraft ever launched, with a 
record 12 instruments on the orbiter and six more instruments on the 
European Space Agency's Huygens probe, which piggybacked a ride to 
Titan on Cassini. Cassini receives electrical power from three 
radioisotope thermoelectric generators, which generate electricity 
from heat produced by the natural decay of plutonium. The spacecraft 
was captured into Saturn orbit in June 2004 and immediately began 
returning data to Earth.

The Cassini-Huygens mission is a cooperative project between NASA, the 
European Space Agency and the Italian Space Agency.

For more information on the Cassini-Huygens mission, visit:

http://www.nasa.gov/cassini
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