NASA extends Cassini's grand tour of Saturn (4/18/2008)

Space physicists continue key work on Saturn mission

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. UK researchers have played key roles in the mission instruments and the scientific discoveries.

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."

Many UK scientists are involved with Cassini-Huygens and looking forward to further discoveries. "Cassini has made many exciting and unexpected discoveries from rings around the moon Rhea to new moons with surprisingly complex features." said Professor Michele Dougherty, Imperial College London, Principal Investigator of Cassini's Magnetometer Instrument. "Amongst the most exciting discoveries are the water-ice geysers jetting from the surface of Saturn's moon, Enceladus. Amazing discoveries like this not only answer many of the questions we have about these complex worlds but pose new mysteries for us to solve."

Based on findings from Cassini, scientists think liquid water may be just beneath the surface of 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.

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.

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

Cassini-Huygens' 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.

Since its landing in January 2005, Huygens has provided a wealth of data that UK scientists are currently analysing. Further work form Cassini will enhance and extend what has been learned from the Huygens data.

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.

Note: This story has been adapted from a news release issued by the Imperial College London

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