The success of Pioneer 11 in repeating an encounter with the giant planet Jupiter and producing unique images of the north polar regions of the planet necessitated an updating of [the previous edition] SP-349. Additional material has been added to the descriptive material about the flight of the spacecraft in Chapter 5. The following chapter, describing the results of the two missions, has been completely updated in the light of further interpretations of the Pioneer 10 data coupled with the new data from Pioneer 11. And additional Chapter 9 has been added to provide a selection of the better images obtained by Pioneer 11. This chapter also includes images of the four Galilean satellites.