y obscured its surface from view. Scientists have guessed at what Titans surface may be like. Some have suggested it is a bizarre, murky swamp of liquid nitrogen and hydrocarbon muck. Others have proposed a global ocean of liquid hydrocarbons, with rains of frozen gasoline. Radar signals bounced off Titan indicate no global oceans, but did produce signals that could be due to local lakes and swamps (Yenne 127).Three American spacecraft have visited Saturn. Pioneer 11 sped by the planet and its moon Titan in September 1979, returning the first close-up images. Voyager 1 followed in November 1980, sending back breathtaking photographs that revealed for the first time the complexities of Saturns ring system and moons. Voyager 2 flew by the planet and its moons in August 1981. As of now, the Cassini-Huygens probe began its 6.7-year voyage to Saturn on Wednesday, October 15, 1997. A U.S. Air Force Titan 4B rocket blasted off with the multi-billion dollar space probe (Yenne 127).Pioneers 10 and 11 were the first spacecraft to visit Jupiter (Pioneer 10 and 11) and Saturn (Pioneer 11 only). Acting as pathfinders for the Voyager missions, the vehicles provided first up-close science observations of these planets, as well as information about the environments that would be encountered by the Voyagers. Instruments abroad the two spacecraft studied Jupiter and Saturns atmospheres, magnetic fields, moons, and rings, as well as the interplanetary magnetic and dust particle environment, the solar wind, and cosmic rays. Following their planetary encounters, some experiments abroad both spacecraft were turned off to save power as the vehicles RTG power output degraded. Pioneer 11s mission ended on September 30, 1995 when its PTG power level was insufficient to operate any experiments and the spacecraft could no longer be controlled. The Voyager 1 flyby of Saturn took place on November 12, 1980 and Voyager 2 flew by Saturn and its moons in...
