 Salyut 4 being constructed | |
 The insignia of the Salyut Program. | |
| Station statistics | |
|---|---|
| COSPAR ID | 1974-104A |
| SATCAT no. | 07591 |
| Call sign | Salyut 4 |
| Crew | 2 |
| Launch | December 26, 1974 04:15:00 UTC |
| Launch pad | LC-81/24, Baikonur Cosmodrome, Soviet Union |
| Reentry | February 3, 1977 |
| Mass |
|
| Length | 15.8 m |
| Width | 4.15 m |
| Pressurised volume | 90 m3 |
| Periapsis altitude | 136 mi (219 km) |
| Apoapsis altitude | 168 mi (270 km) |
| Orbital inclination | 51.6 degrees |
| Orbital period | 89.1 minutes |
| Days in orbit | 770 days |
| Days occupied | 92 days |
| No. of orbits | 12,444 |
| Distance travelled | ~313,651,190 mi (~504,772,660 km) |
| Statistics as of de-orbit and reentry | |
| Configuration | |
 Salyut 4 and Soyuz diagram | |
Salyut 4 (DOS 4) (Russian: Салют-4; English translation: Salute 4) was a Salyut space station launched on December 26, 1974 into an orbit with an apogee of 355 km, a perigee of 343 km and an orbital inclination of 51.6 degrees. It was essentially a copy of the DOS 3 (or Kosmos 557), and unlike its ill-fated sibling it was a complete success. Three crews attempted to make stays aboard Salyut 4 (Soyuz 17 and Soyuz 18 docked; Soyuz 18a suffered a launch abort). The second stay was for 63 days duration, and an unmanned capsule, called Soyuz 20, remained docked to the station for three months, proving the system's long-term durability despite some deterioration of the environmental system during Soyuz 18's mission. Salyut 4 was deorbited February 2, 1977, and re-entered the Earth's atmosphere on February 3.