Manned Venus Flyby was a 1967–1968 NASA proposal to send three astronauts on a flyby mission to Venus in an Apollo-derived spacecraft in 1973–1974, using a gravity assist to shorten the return journey to Earth.
The planet Venus, viewed in true color from Mariner 10
Cutaway diagram of the Venus flyby spacecraft
Artist's depiction of TMK-MAVR on a Venus flyby
The colonization of Venus has been a subject of many works of science fiction since before the dawn of spaceflight, and is still discussed from both a fictional and a scientific standpoint. However, with the discovery of Venus's extremely hostile surface environment, attention has largely shifted towards the colonization of the Moon and Mars instead, with proposals for Venus focused on habitats floating in the upper-middle atmosphere and on terraforming.
Artist's rendering of a crewed floating outpost on Venus of NASA's High Altitude Venus Operational Concept (HAVOC)
The surface of Venus is completely covered by clouds which prevent most heat from escaping.
Artist's conception of a terraformed Venus. The cloud formations are depicted assuming the planet's rotation hasn't been sped up.