TMKTMK TMK TMK ( - "Tyazhely Mezhplanetny Korabl" or "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. 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. TMK-1. The first flight to Mars of the TMK-1 was planned to begin on June 8, 1971. The 75 metric ton TMK-1 spacecraft would take a crew of three on a Mars flyby mission. After a 10½ month flight the crew would race past Mars, dropping remote-controlled landers, and then be flung into an Earth-return trajectory. Earth return would happen on July 10, 1974, after a voyage of three years, one month, and two  days. Spacecraft configuration: TMK-E. This variation was proposed in 1960, and consisted of a complete Mars landing expedition to be assembled in Earth orbit using several N1 launches. The spacecraft would be powered by nuclear electric engines and five landers would deliver a nuclear-powered "Mars Train" on the surface for a one-year mission. The TMK-E would be capable of a three-year flight to Mars and return, of which one year was powered flight. It would measure 175 m in length and house a crew of six. Six landing craft were included, two for the crew  and four for the "Mars Train" vehicles. Mavr (MArs - VeneRa). A variation of the TMK mission planning involved a flyby of Venus on the return voyage, and was given the code name "Mavr" ("MArs - VeneRa"), meaning Mars - Venus. KK - Space Complex for Delivering a Piloted Expedition to Mars. In 1966, a final version of the TMK studies was known as "KK - Space Complex for Delivering a Piloted Expedition to Mars". Nuclear electric propulsion was to be used for the 630-day mission. The craft structure consisted of: The launch was planned for 1980, with a crew of three cosmonauts. Mars  stay duration would be 30 days. Mission data: TMK TMK ( - "Tyazhely Mezhplanetny Korabl" or "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. 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