NASA studied a proposal in the late 1960s to send three astronauts on a flyby of Venus, rather than land them there, using Apollo-derived hardware and a Saturn V rocket. The abandoned concept illustrates how the Apollo programme briefly opened the possibility of more ambitious human missions beyond the Moon, before changing priorities and funding pressures narrowed NASA’s plans.

The proposed mission would have launched in 1973, passed Venus in 1974 and returned to Earth after roughly a year in space. Its spacecraft would have combined an Apollo command and service module with the spent rocket stage as additional living space, while Venus’s gravity would have helped direct the crew home. It remained a feasibility study, not an approved flight, and no astronauts have travelled beyond lunar distance.