TMK was the designation of a Soviet space exploration project to send a crewed flight to Mars and Venus without landing.
Artist's depiction of TMK-MAVR on a Venus flyby
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