Figure 6. An artist's painting of the Pioneer 10/ Pioneer 11 spacecraft. In flight, each spacecraft rotates around the axis of the 9-foot diameter para­bolic antenna which is kept pointed continuously at the Earth. The three long booms were deployed after launch. The one to the lower left supports a magnetometer; the ones upward and to the lower right sup­port the radioisotope thermal gener­ators which supply electrical power to the radio transmitter and all of the electronic systems and instruments. The central body contains scientific instruments including the one that was designed and built at the Uni­versity of Iowa. Pioneer 10 was launched on 2 March 1972, passed through the asteroid belt between Mars and Jupiter, and made the first ever encounter with Jupiter. Pioneer 11 was launched on 5 April 1973, made the second encounter with Jupiter and the first ever encounter with Saturn. Both spacecraft con­tinue to operate well as of 1992 and both are escaping from the solar system.