Salyut 4
Salyut 4 being constructed
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Salyut 4 diagram
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The insignia of the Salyut Program.
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| Station statistics | |
|---|---|
| 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 |
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| Length | 15.8 m |
| Width | 4.15 m |
| Pressurised volume | 90 m³ |
| Perigee | 136 mi (219 km) |
| Apogee | 168 mi (270 km) |
| Orbital inclination | 51.6 degrees |
| Orbital period | 89.1 minutes |
| Days in orbit | 770 days |
| Days occupied | 92 days |
| Number 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
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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, 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 Soyuz capsule 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.
Salyut 4 represented the second phase of DOS civilian space station. Although the basic design of Salyut 1 was retained, it switched to three large solar panels mounted on the forward module rather than its predecessor's four small panels on the docking module and engine compartment, presumably to generate more power. It had an interior floor area of 34.8 sq. The pitch of the station was 2 X 59 N, yaw was 2 X 59 N and roll was 2 X 20 N. The electric System produced an average of 2.00 kW of power. It had 2,000 kg of scientific equipment alongside two sets of three solar panels each and was equipped with the Delta Navigation System which was a new autonomous navigation system that calculates orbital elements without assistance from ground. It was powered by KTDU-66 thrusters.
Installed on the Salyut 4 were OST-1 (Orbiting Solar Telescope) 25 cm solar telescope with a focal length of 2.5m and spectrograph shortwave diffraction spectrometer for far ultraviolet emissions, designed at the Crimean Astrophysical Observatory, and two X-ray telescopes. One of the X-ray telescopes, often called the Filin telescope, consisted of four gas flow proportional counters, three of which had a total detection surface of 450 cm² in the energy range 2–10 keV, and one of which had an effective surface of 37 cm² for the range 0.2 to 2 keV (32 to 320 aJ). The field of view was limited by a slit collimator to 3 in × 10 in full width at half maximum. The instrumentation also included optical sensors which were mounted on the outside of the station together with the X-ray detectors, and power supply and measurement units which were inside the station. Ground based calibration of the detectors was considered along with in-flight operation in three modes: inertial orientation, orbital orientation, and survey. Data could be collected in 4 energy channels: 2 to 3.1 keV (320 to 497 aJ), 3.1 to 5.9 keV (497 to 945 aJ), 5.9 to 9.6 keV (945 to 1,538 aJ), and 2 to 9.6 keV (320 to 1,538 aJ) in the larger detectors. The smaller detector had discriminator levels set at 0.2 keV (32 aJ), 0.55 keV (88 aJ), and 0.95 keV (152 aJ).
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