The Cassini spacecraft is now two and half years through its official „primary tour“ of the Saturn system which is scheduled to last another 17 months before ending on June 30, 2008. During this primary tour Cassini will have made 46 close flybys of Titan (during one of which it dropped off the successful European Space Agency’s Huygens Titan lander), four close flybys of the unexpectedly fascinating moon Enceladus, and one each of Tethys, Dione, Rhea, Hyperion, Iapetus and Phoebe. On the basis of what is done so far Cassini must be considered a scientific and space art spectacular. It has revealed major new mysteries about Titan and Enceladus which have a direct relevance to the possibility that one or both moons have evolved microscopic life. Moreover, Cassini has apparently solved at least two of the biggest scientific mysteries about the Saturn system: the mysterious longevity of its ring system, and the remarkable difference between Iapetus‘ black leading side and its bright whitish trailing side. Later this year in September, having completed most of the planned flybys of Saturn’s smaller moons, Cassini will make its one close flyby of the distant and hard-to-reach moon Iapetus. Coming within 1.500 km it will be able to make its best observations of Iapetus and hopefully solve the remaining puzzles about it. The following March in 2008 Cassini will make its closest flyby of Enceladus skimming a mere 23 km above the geyser-like water and ice plumes which are erupting from the south polar region. Scientists working with Cassini are looking at how an extended mission would work. From the time Cassini first entered orbit around Saturn, they have been working on the design of a possible extended tour, re-planning it on the basis of the craft’s new discoveries about the Saturn system.
Cassini: Mission to Saturn

ESA – Cassini-Huygens