The primary antenna feed offset bellows failed sometime in 1976 but a redundant unit was available for use thereafter. The Backup Line Heater experienced a sticking thermostat operation in March 1993 for 30 days but the problem did not reoccur. Undervoltage Protection Logic was turned off in December 1993 to prevent loss of critical spacecraft systems in the event of a transient undervoltage condition. Atlas Centaur SLV-3D . Saturn flyby September 1979.
Solar system escape trajectory.
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. The spacecraft has operated on a backup transmitter since launch. Instrument power sharing began in February 1985 due to declining RTG power output.