By Victoria Gill

Science reporter, BBC News



Cassini completed its initial four year mission to explore Saturn in June 2008

The US space agency Nasa has extended the international Cassini-Huygens mission once again.

The unmanned Cassini-Huygens probe arrived at Saturn in 2004 on a mission that was meant to come to end in 2008.

Its mission had already been extended up to 2010. Nasa now says the spacecraft will explore the Saturn system until 2017.

Dr Jim Green, director of Nasa's planetary science division, announced the extension on Wednesday.

"We have now an approved Cassini extended extended mission," he said during a meeting of Nasa's planetary science sub-committee.

In 2007, Cassini discovered a new ring around Saturn and since the mission's first extension, the probe obtained evidence that one of Saturn's moons, Enceladus, retains liquid water beneath its surface.