The exploration of Venus

This paper is an introduction to a special issue ofSpace Science Reviews dedicated to the exploration of Venus and the role played by the Pioneer Venus program. The Pioneer Venus program consists of a Multiprobe and Orbiter mission, both to be launched and to encounter Venus in 1978. The evolution of the program is traced from its conception in 1968 as the Goddard Space Flight Center Planetary Explorer Program through its transfer to Ames Research Center in 1971 as Pioneer Venus to the present.