A year after entering orbit around Saturn, the Cassini-Huygens team is looking back at a string of remarkable discoveries. Numerous discoveries have been made about Titan's surface and atmosphere, Saturn's magnificent rings, its amazing moons, dynamic magnetosphere and the planet itself. The highlight of the mission so far is clearly the lifting of the veil on smog-covered Titan. The orbiter's remarkable instruments provided the first glimpses of the surface and the global picture of the hazy world. The Huygens probe touchdown provided a close-up look of a whole new world, much like our own.
What scientists expected to see and did not see is equally interesting. The scientists' original ideas for Titan's surface included global oceans and lakes of liquid hydrocarbons. The Huygens probe was even designed to float briefly, since a liquid landing was deemed very likely. Small lakes may exist, but global oceans are just not there. This lack of large bodies of liquid may cause scientists to rethink the age and origin of Titan's atmosphere.
Spokes in Saturn's B ring, as seen by NASA's Voyager spacecraft, were also anticipated. To date, we have not seen spokes in geometries where they should have been seen if their associated dust clouds were present. This lack of spokes shows that important electrostatic or electrodynamic effects, like photoelectric charging of the rings, vary seasonally.
On July 14, Cassini made its closest flyby yet, swinging about 175 kilometers (109 miles) above the surface of Saturn's moon Enceladus. Other exciting events include flybys of "six worlds in 80 days," including two flybys of Titan and one each of the moons Tethys, Hyperion, Dione and Rhea. During the October flyby of Titan we will obtain a radar swath over the Huygens landing site, which will help scientists put the rest of Titan in context with the portion studied in detail by the probe.