|Ray Bradbury at the 1980 Voyager Saturn Encounter at the Jet Propulsion Laboratory. Chris Gainor photo|
Cassini's arrival at Saturn marked the first visit by a spacecraft to the ringed planet in nearly 23 years. Only three spacecraft had gone there before, all of those visits taking place in a narrow two-year time span – Pioneer 11 on September 1, 1979, Voyager 1 on November 12, 1980, and Voyager 2 on August 26, 1981.
Pioneer 11’s mission was mainly as a pathfinder, proving that spacecraft could survive the rigors of passages through the asteroid belt, the Jovian and Saturnian magnetic fields, and Saturn’s ring plane. Its primitive imager gave scientists and the public only a taste of the views Jupiter and Saturn offered.
Much of the future of planetary exploration hinged on the success of this encounter, because Voyager 1 had the dual mission of passing close to both Saturn and its moon Titan, the only moon in the solar system known in 1980 to have an atmosphere.
Titan's importance was shown by the fact that Voyager 1's path by Titan would direct it away from the orbital plane of the other planets. Only if Voyager 1 succeeded in getting data from Titan on its way in toward Saturn would Voyager 2 be freed to take a path by Saturn that would direct it to Uranus and hopefully Neptune. A failure of Voyager 1’s Titan encounter would mean that Voyager 2 would be directed to pass close to Titan, and that path would exclude further Voyager planetary encounters.