Credit: NASA/JPL/Space Science Institute

NASA has extended the highly successful Cassini-Huygens mission to Saturn by two years. The historic spacecraft's stunning discoveries and incredible images have revolutionized our knowledge of Saturn and its large system of at least 60 moons.

Cassini entered orbit around Saturn in July 2004. The mission had originally been scheduled to end in July 2008. The mission extension will feature 60 new orbits of Saturn and more flybys of its bizarre moons. There will be 26 flybys of Titan (5,150 km across), Saturn’s largest moon, seven of Enceladus (497 km across), a geologically-active moon, and three more flybys of three other Saturnian moons. The extension also includes studies of Saturn's rings, its intricate 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 of NASA’s Planetary Science Division. "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 (JPL).

Enceladus, only one-seventh the size of Earth’s Moon (3,476 km across), is a high priority target for the mission extension. In 2005, Cassini discovered amazing plumes of icy material erupting from the moon’s southern polar regions. This is an intriguing type of volcanism, known as cryovolcanism. Actually, Enceladus is among a handful of volcanic objects in the Solar System.

Titan’s diameter is about 50% larger than that of our Moon, while Titan’s mass is approximately twice that of the Moon. In January 2005, the Cassini-Huygens mission achieved history when the Huygens probe separated the Cassini spacecraft and landed successfully on Titan, becoming the first space probe to touchdown on a planetary moon.
Titan is the only moon known to have a substantial atmosphere. It may be even described as an Earth-like moon. The present conditions on Titan resemble those believed to have prevailed on the early Earth, but Titan has a much colder temperature of nearly -180 C. By studying Titan, scientists hope to get new insights into our planet’s evolution.

Cassini’s observations yielded convincing evidence that Titan has large lakes and seas. These lakes and seas are most probably filled with liquid hydrocarbons, such as methane and ethane.

During 62 orbits around Saturn, Cassini has returned a daily stream of data, including nearly 140,000 images and information gathered through close encounters of the exotic icy moons. Cassini has been flying in space for over 10 years, since launch in October 1997. It traversed 3.5 billion km across the Solar System to reach the Saturn system.

The Cassini scientists report that the spacecraft is healthy and robust. Three of its 12 science instruments have just minor ailments that do not affect the science operations. Cassini receives electrical power from three radioisotope thermoelectric generators, which generate electricity from heat released by the natural decay of plutonium.

The spacecraft propellant is expected to suffice for a possible third phase of operations, beyond the mission extension. Data from the extended mission would inspire new missions to Titan and Enceladus.

Further Reading

NASA’s Cassini Websites
http://www.nasa.gov/cassini  
http://saturn.jpl.nasa.gov

Aymen Mohamed Ibrahem
Senior Astronomy Specialist