On Sept. 29, 1977, the Soviet Union launched the Salyut 6 space station, the first second-generation station designed for long-duration missions. It hosted 16 cosmonaut crews over five years, with the longest stay lasting 185 days. Salyut 6 deorbited in 1982, burning up in Earth's atmosphere.
Salyut 6: Soviet Space Station Launched for Long Missions
Source: Space