On Dec. 26, 1974, Salyut 4, a Soviet space station, launched into orbit around Earth.

Salyut 4 was a small space station about the size of a school bus. It was almost identical to its sibling space station DOS 3, which failed to make it to orbit. Salyut 4 launched from the Baikonur Cosmodrome in Kazakhstan and entered an orbit 217 miles above the Earth. Three cosmonaut crews attempted to stay aboard Salyut 4, but they didn't all make it there successfully. The first mission, Soyuz 17, arrived about two weeks after Salyut 4 launched. The first two cosmonauts to visit Salyut 4 spent 29 days on board. A couple months later, a second Soyuz crew (18) launched to the space station, but they never made it there. The spacecraft failed to reach orbit, but luckily the crew survived. Just seven weeks later, a third crew (19) successfully launched to Salyut 4, and they ended up staying for 63 days. After they left, Salyut 4 stayed in orbit for another year and a half before it deorbited and burned up in Earth's atmosphere.