Salyut 4 Credit - © Mark Wade

Four of the initial DOS-1 versions of a civilian Soviet space station were built using converted Almaz military stations. DOS-1 was launched as Salyut 1 on 19 April 1971. The triumph turned to tragedy when the Soyuz-11 crew died due to de-pressurization of their re-entry capsule during return to the earth. Launches of the first series DOS stations continued in a desperate effort to beat Skylab into orbit with a fully successful Soviet space station mission. DOS-2, s/n 122, was destroyed in a launch vehicle explosion en route to orbit in July 1972. DOS-3, s/n 123, reached orbit as Cosmos 557 in 1973 but control was lost before a crew could be sent to the station. DOS-4, the last of the first series, finally flew successfully as Salyut 4 in 1974. Salyut 4 differed from Salyut 1 in having three sets or rotatable solar panels, more electrical power, and a more complete equipment suite.

Salyut 4 in Assembly Salyut 4 in Assembly Hall... Credit- RKK Energia

Salyut 4 represented the second phase of DOS civilian space station. It had 2,000 kg of scientific equipment and two sets of 3 solar panels. It was equipped with the Delta navigation system. Experiments: - Solar telescope OST-1 with main mirror of 25 cm diameter, 2.5 m focal length, built by Crimean Astrophysical Observatory with spectrograph shortwave diffraction spectrometer for far ultraviolet emissions, oriented by maneuvering entire station - two X-ray telescopes - swivel chair for vestibular function tests - lower body negative pressure gear for cardiovascular studies - bicycle ergometer integrated physical trainer (electrically driven running track 1 m X .3 m with elastic cords providing 50 kg load) - penguin suits and alternate athletic suit - 15 medical experiments total - sensors for temperature and characteristics of upper atmosphere ITS-K infrared telescope spectrometer and ultraviolet spectrometer for study of earth's infrared radiation - multispectral earth resources camera - cosmic ray detector - embryological studies - new engineering instruments tested for orientation of station by celestial objects and in darkness - New autonomous navigation system calculates orbital elements without assistance from ground - teletypewriter - two spherical airlocks near main camera to ejects body wastes. Interior floor area: 34.8 sq. m

Typical orbit: 223 km circular orbit, 51.5 deg inclination. Length: 13.07 m (42.88 ft). Maximum Diameter: 4.15 m (13.61 ft). Span: 17.00 m (55.00 ft). Mass: 18,210 kg (40,140 lb). RCS Coarse No x Thrust: Verniers: 4 X 98 N - Pitch: 2 X 59 N - Yaw: 2 X 59 N - Roll: 2 X 20 N. RCS Fine No x Thrust: 18 x 10 N. RCS Coarse Backup No x Thrust: 4 x 98 N. Main Engine: KTDU-35. Main Engine Thrust: 4.089 kN (919 lbf). Main Engine Propellants: Nitric Acid/Hydrazine. Main Engine Propellants: 2,000 kg (4,400 lb). Main Engine Isp: 282 sec. Backup Main Engine Thrust: 4.030 kN (906 lbf). Spacecraft delta v: 320 m/s (1,040 ft/sec). Electrical System: Solar Panel Span: 17.0 m, area: 60 sq. m. Electric System: 2.00 average kW. Associated Launch Vehicle: Proton 8K82K.

• 1973 May 11 - Cosmos 557 - Program: Salyut. Launch Site: Baikonur. Launch Vehicle: Proton. Mass: 19,400 kg (42,700 lb). Perigee: 206 km (128 mi). Apogee: 225 km (139 mi). Inclination: 51.60 deg. Period: 88.90 min. Duration: 10.98 days.

  Salyut failure. Unsuccessful mission. Salyut out of control. Decayed May 22, 1973. Was to have been manned by initial crew of Leonov and Kubasov. Last chance to upstage Skylab, launched three days later.

• 1974 December 26 - Salyut 4 - Program: Salyut. Launch Site: Baikonur. Launch Vehicle: Proton. Mass: 18,500 kg (40,700 lb). Perigee: 212 km (131 mi). Apogee: 251 km (155 mi). Inclination: 51.60 deg. Period: 89.10 min. Duration: 768.82 days.

  Salyut 4 toilet View of Salyut 4 toilet facility - you always wanted to know how they do it in space...... Credit- © Mark Wade

  Deorbited February 2, 1977.
  Maneuver Summary:
  211km X 250km orbit to 215km X 286km orbit. Delta V: 11 m/s
  211km X 284km orbit to 276km X 344km orbit. Delta V: 35 m/s
  277km X 342km orbit to 338km X 351km orbit. Delta V: 19 m/s
  330km X 340km orbit to 337km X 350km orbit. Delta V: 4 m/s
  337km X 349km orbit to 339km X 351km orbit. Delta V: 1 m/s
  332km X 348km orbit to 348km X 355km orbit. Delta V: 6 m/s
  347km X 354km orbit to 343km X 351km orbit. Delta V: 1 m/s
  335km X 344km orbit to 335km X 360km orbit. Delta V: 4 m/s
  335km X 360km orbit to 342km X 361km orbit. Delta V: 2 m/s
  330km X 351km orbit to 344km X 353km orbit. Delta V: 4 m/s
  186km X 187km orbit to 90km X 186km orbit. Delta V: 28 m/s
  Total Delta V: 87/115 m/s.
  Officially: Further testing of station design, on-board systems and equipment; conduct of scientific and technical research and experiments in outer space. Further testing of station design, on-board systems and equipment; conduct of scientific and technical researc h and experiments in outer space.

• 1977 February 2 - Burnup of the Salyut 4 Space Station (USSR) -