Pioneer Venus and Galileo entry probe heritage

Beginning in the late 1960s, NASA began planning for its first program to explore Venus. Although planetary entry probes had been flown to Venus by the Soviets beginning in 1967, NASA had not previously flown this type of mission. The Space and Communications Group of Hughes Aircraft Company, now owned by Boeing and called Boeing Satellite Systems, worked with NASA to perform initial studies that culminated with a contract for the Pioneer Venus program in early 1974. Pioneer Venus was an ambitious program that included four planetary entry probes, transported to Venus by a Multiprobe Bus, and a Venus Orbiter. This paper focuses on the engineering aspects of the probes and the challenges overcome in accommodating the various scientific instruments. The second NASA planetary entry program was the Galileo Mission that began with initial studies in the early 1970s. This mission to Jupiter included both an Orbiter and a Probe. Although the Galileo Probe planetary entry program was begun as the Pioneer Venus probes were heading towards Venus, there were significant engineering differences between the Pioneer Venus probe designs and the Galileo Probe. These differences, dictated by a number of factors, are discussed. The paper concludes with a summary of lessons learned by Boeing and NASA in designing, manufacturing and ultimately flying the Venus and Jupiter planetary entry probes.