Pioneer 11Pioneer 11 was the second mission to investigate Jupiter and the outer solar system and the first to explore the planet Saturn and its main rings. Pioneer 11, like Pioneer 10, used Jupiter's gravitational field to alter its trajectory radically. It passed close to Saturn and then it followed an escape trajectory from the solar system.
During its closest approach on December 4, 1974, Pioneer 11 passed to within 34,000 km of Jupiter's cloud tops. It passed by Saturn on September 1, 1979, at a distance of 21,000 km from Saturn's cloud tops.
Pioneer 11 was last heard from on September 30, 1995 when the RTG power level became too low to operate any experiments.