On April 19, 1971, the USSR launched the first manned space station, Salyut 1, into orbit around Earth.
The station consisted of four compartments, and was meant to house three crew members for up to 4 weeks.
The entry compartment had the docking equipment for the spacecraft that would carry cosmonauts to and from the station.
The work compartments, cylinders approximately 10 feet (2.9 m) around x 13 feet (3.9 m) long and 14 feet (4.15 m) x 13.5 feet (4.1 m), held the controls, instruments, a treadmill, a table, and sanitation fixtures.
The fourth compartment stored the propulsion system.
The first five Salyut stations mostly failed to work properly.
Salyut 6 and Salyut 7 were modified and were home to many successful long-term and record-breaking missions between 1977 and 1986.
In 1986, the USSR’s Mir space station took over.