Human Spaceflights

International Flight No. 56

Soyuz 21



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Launch, orbit and landing data

Launch date:  06.07.1976
Launch time:  12:09 UTC
Launch site:  Baikonur
Launch pad:  1
Altitude:  193 - 253 km
Declination:  51,59°
Docking Salyut 5:  07.07.1976, 13:40 UTC
Undocking Salyut 5:  24.08.1976, 15:12 UTC
Landing date:  24.08.1976
Landing time:  18:33 UTC
Landing site:  200 km SW of Kokchetav

alternate crew photo

alternate crew photo

alternate crew photo

alternate crew photo

alternate crew photo


No.   Surname Given names Position Flight No. Duration Orbits
1  Volynov  Boris Valentinovich  Commander 2 49d 06h 23m  791 
2  Zholobov  Vitali Mikhailovich  Flight Engineer 1 49d 06h 23m  791 

Crew seating arrangement

1  Volynov
2  Zholobov
1  Volynov
2  Zholobov

Animations: Soyuz

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1st Double Crew

No.   Surname Given names Position
1  Zudov  Vyacheslav Dmitriyevich  Commander
2  Rozhdestvensky  Valeri Iliych  Flight Engineer

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2nd Double Crew

No.   Surname Given names Position
1  Gorbatko  Viktor Vasiliyevich  Commander
2  Glazkov  Yuri Nikolayevich  Flight Engineer

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Launch from the Baikonur Cosmodrome; landing 200 km southwest of Kokchetav.

Following a one day solo flight Soyuz 21 docked with Salyut 5 on July 07, 1976. The spacecraft with Boris Volynov and Vitali Zholobov aboard hard-docked with the station on July 06, 1976 after a failure of the Igla system at the last stage of the rendezvous.

Their stay coincided with the start of the Siber military exercise in Siberia, which they observed as part of an assessment of the station’s military surveillance capabilities. They conducted only a few scientific experiments, including the first use of the Kristall furnace for crystal growth. Engineering experiments included propellant transfer system tests with implications for future operation of the freight-carrying Progress spacecraft.

Observation of aquarium fishes in the microgravity was done too. Solar observation and biological observation (plant growing) were carried out. The Kalialaun-experiment was needed for the observation of crystal grooving in space. Also a TV conference with pupils was held.

Towards the end of the two month mission an early return to earth was requested due to the poor condition of Flight Engineer Vitali Zholobov (who was suffering from space sickness and psychological problems). The crew landed in very bad physical and mental condition.
Vitali Zholobov's illness was apparently caused by nitric acid fumes leaking from the Salyut's propellant tanks; other reports, however, indicate that the crew failed to follow their physical exercise program and suffered from lack of sleep. Sources at NASA have reported that psychologists with the Russian Aviation and Space Agency cited Soyuz 21 as ending prematurely due to unspecified "interpersonal issues" with the crew. The next mission to successfully dock with the station, Soyuz 24, would vent Salyut 5's air to space and replace it due to concerns the air had become toxic.

The cosmonauts boarded Soyuz 21 but as Boris Volynov tried to undock from the station, the docking latches failed to release properly. As he fired the jets to move the spacecraft away, the docking mechanism jammed, resulting in the Soyuz being undocked but still linked to Salyut. As the two spacecraft moved out of range of ground communications, the cosmonauts received only the first set of emergency procedures. Boris Volynov tried a second time to undock but only managed slightly to loosen the latches. The situation persisted for an entire orbit, 90 minutes, when the final set of emergency procedures were received and the crew finally disengaged the latches.

Because Soyuz 21 was returning early, it was outside the normal recovery window. It then encountered strong winds as it descended, which caused uneven firing of the retrorockets. It made a hard landing around midnight.

Photos / Drawings

crew in training


Last update on June 25, 2014.