TMK

TMK (Russian: Тяжелый Межпланетный Корабль, romanized: Tyazhelyy Mezhplanetnyy Korabl', lit. 'Heavy Interplanetary Vessel') was the designation of a Soviet space exploration project to send a crewed flight to Mars and Venus (TMK-MAVR design) without landing.^[1][2]

The TMK-1 spacecraft was due to be launched in 1971 and make a three-year-long flight including a Mars flyby, at which time probes would have been dropped. Expanded project variations, such as the TMK-E, Mavr or KK, including a Venus flyby, electric propulsion or a crewed Mars landing were also proposed.

The TMK project was planned as a response to the United States' crewed Moon landings. An earlier Martian Piloted Complex mission was proposed in 1956. The project was never completed because the required N1 rocket never flew successfully.