Soyuz 18 (Russian: Союз 18, Union 18) was a 1975 Soviet manned mission to Salyut 4, the second and final crew to man the space station. Pyotr Klimuk and Vitali Sevastyanov set a new Soviet space endurance record of 63 days and the mark for most people in space simultaneously (seven) was tied during the mission.
Read more about Soyuz 18: Crew, Mission Parameters, Mission Highlights