Salyut Four Details

Introduction

Salyut Four (Durable Orbital Station Four or DOS-4) was the second successful civilian space station launched. Two previous stations DOS-2 and DOS-3 failed to reach orbit.

Salyut Four was launched on December 26, 1974 and accommodated two crews for a total of 93 days. An un-crewed capsule, Soyuz 20, remained docked to the station for three months, proving the system's long-term durability. Salyut 4 was de-orbited February 2, 1977, and destroyed.

Reference: Wikipedia - Salyut 4

Salyut 4 / Soyuz 7K-T
[Click image to enlarge]

Design

The basic design of Salyut Four was similar to that of Salyut One with some major changes. To produce more power it has three large solar panels mounted on the forward module rather than Salyut One's four small panels on the docking module and engine compartment.

Salyut Four had an interior floor area of 34.8 m²; the electric System produced an average of 2.00 kW and it could accommodate 2,000 kg of scientific equipment. It was also equipped with a new autonomous navigation system, the Delta Navigation System, that calculates orbital elements without assistance from ground.

Instrumentation

The OST-1 (Orbiting Solar Telescope) was installed on Salyut Four. This 25 cm solar telescope had a focal length of 2.5m with a spectrograph shortwave diffraction spectrometer for far ultraviolet emissions and two X-ray telescopes.

The instrumentation also included optical sensors which were mounted on the outside of the station together with the X-ray detectors, and power supply. Other instruments included a swivel chair for vestibular function tests, lower body negative pressure gear for cardiovascular studies, bicycle ergometer, penguin suits and alternate athletic suits.

Salyut 4 in factory (Credit: SpaceFacts)

Specifications

Length: 15.8 m
Diameter: 4.15 m
Habitable volume: 90 m³
Mass at Launch: 18,210 kg
Solar Arrays Area (3): 60 m²
Power: 4 kW
Major Docking Ports: 1
Main engines: KTDU-66 thrusters

Missions and Statistics

The table below gives a summary of the missions to Salyut Four (DOS-4) station, including some basic Statistics.

The Salyut Four module and all spacecraft were launched from Baikonur Cosmodrome with an orbital inclination of 51.6 degrees.

Launch		Re-Entry		Spacecraft ℹ Transport crews and cargo to and from the station	Crew No. ℹ Number of crew on mission	Carrier Rocket ℹ Launch vehicle used to carry station or craft to orbit.	Duration (Days) ℹ Number of days in orbit	Perigee (km) ℹ Lowest orbital altitude	Apogee (km) ℹ Highest orbital altitude	Orbit (Mins.) ℹ Time taken to orbit the Earth.	Mission Notes ℹ General notes on the mission
Year	Date	Year	Date

1974	Dec 26	1977	Feb 3	Station Module		Proton-K	770	219	270	89.1	Second civilian station.
1975	Jan 10	1975	Feb 9	Soyuz 17	2	Soyuz	29	293	354	91.7	First crew on Salyut 4.
	Apr 5		Apr 5	Soyuz 18a	2	Soyuz	0	192	192	90.0	Soyuz 18a failed to reach orbit and returned to Earth.
	May 24		Jul 26	Soyuz 18	2	Soyuz U	63	193	247	88.6	Second and last crew on Salyut 4.
	Nov 17	1976	Feb 16	Soyuz 20	0	Soyuz U	90	200	263	88.8	Un-crewed long duration test of Soyuz crew craft.