Salyut 4 was a Soviet space station launched on December 26, 1974. It was part of the Salyut program, which aimed to develop space stations for scientific research and military purposes. Salyut 4 operated in low Earth orbit and was equipped with various instruments for experiments in fields like biology, astronomy, and materials science. The space station was inhabited by two crews, with the first mission lasting 23 days and the second lasting 15 days. Salyut 4 was notable for its successful docking with the Soyuz 16 spacecraft, allowing astronauts to transfer supplies and conduct research in space before it was decommissioned in 1977.