Soyuz 21

Soyuz 21 (Russian: Союз 21, Union 21) was a 1976 Soviet manned mission to the Salyut 5 space station, the first of three flights to the station.^[2] The mission's objectives were mainly military in scope, but included other scientific work. The mission ended abruptly with cosmonauts Boris Volynov and Vitaly Zholobov returning to earth after 49 days in orbit. The precise reason for the early end of the mission was the subject of much speculation, but was reported to be an emergency evacuation after the Salyut atmosphere developed an acrid odor.

Crew

Backup crew

Reserve crew

Mission parameters

• Mass: 6,800 kg (15,000 lb)
• Perigee: 246 km (153 mi)
• Apogee: 274 km (170 mi)
• Inclination: 51.6°
• Period: 89.7 min

Mission highlights

Salyut 5, the last dedicated military space station in the Soviet space program,^[3] was launched 22 June 1976. Its first crew was launched 14 days later on 6 July, with Commander Volynov and Flight Engineer Zholobov aboard Soyuz 21. Based on landing opportunities, observers estimated the mission was intended to last 54 to 66 days.^[3] They docked with the station the next day, and gave a televised tour 8 July.^[3]

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.

Experiments conducted during the mission were mainly of a military nature as part of the Almaz program. Various purely scientific tasks were also carried out, including solar observations and biological observations of an aquarium of fish carried into orbit.^[3] A TV link-up with school children on 17 August was also undertaken.^[3]

On 24 August, it was announced the mission was to end in only 10 hours, a development which caught even the reporters of Radio Moscow by surprise.^[3] The reason for the sudden termination of the mission was reported at the time to have been an acrid odor that developed in the environmental control system. The problem was said to have begun as early as 17 August.^[3] The Soviets made no comments at the time, but the next crew to board the station wore breathing masks.^[4] Later reports indicate that the mission may have ended owing to a deterioration in the health of Zholobov.

The cosmonauts boarded Soyuz 21 but as 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. 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 200 km (120 mi) southwest of Kokchetav, Kazakhstan.

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.^[5] 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.^[6] 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.

References

Soyuz human spaceflight programme
Main topics	Soyuz (rocket family) Soyuz (spacecraft) Baikonur Cosmodrome Site 1/5 Site 31/6 List of Soyuz missions List of Soviet manned space missions List of Russian manned space missions
Current missions	Soyuz MS-02 MS-03
Future missions	2017 Soyuz MS-04 MS-05 MS-06 MS-07 2018 Soyuz MS-08 MS-09 MS-10
Past missions (by spacecraft type)	Soyuz 7K-OK (1966–1970) Kosmos 133† Soyuz 7K-OK No.1† Kosmos 140 Soyuz 1† Kosmos 186 188 212 213 238 Soyuz 2 3 4 5 6 7 8 9 Soyuz 7K-L1 (1967–1970) (Zond lunar programme) Kosmos 146 154† Zond 1967A† 1967B† Zond 4 1968A† 1968B† 5 6 1969A† Zond-M 1† M 2† Zond 7 8 9 10 Soyuz 7K-L1E (1969–1970) Soyuz 7K-L1E No.1† Kosmos 382 Soyuz 7K-LOK (1971–1972) Soyuz 7K-LOK No.1† No.2† Soyuz 7K-OKS (1971) Soyuz 10† 11† Soyuz 7K-T (1972–1981) Kosmos 496 573 Soyuz 12 Kosmos 613 Soyuz 13 Kosmos 656 Soyuz 14 15† 17 18a† 18 20 (uncrewed) 21 23† 24 25† 26 27 28 29 30 31 32 (uncrewed landing) 33† 34 (uncrewed launch) 35 36 37 38 39 40 Soyuz 7K-TM (1974–1976) Kosmos 638 672 Soyuz 16 19 (Apollo–Soyuz Test Project) 22 Soyuz 7K-S (1974–1976) Kosmos 670 772† 869† Soyuz-T (1978–1986) Kosmos 1001† 1074 Soyuz T-1 (uncrewed) T-2 T-3 T-4 T-5 T-6 T-7 T-8† T-9 T-10a† T-10 T-11 T-12 T-13 T-14 T-15 Soyuz-TM (1986–2002) Soyuz TM-1 (uncrewed) TM-2 TM-3 TM-4 TM-5 TM-6 TM-7 TM-8 TM-9 TM-10 TM-11 TM-12 TM-13 TM-14 TM-15 TM-16 TM-17 TM-18 TM-19 TM-20 TM-21 TM-22 TM-23 TM-24 TM-25 TM-26 TM-27 TM-28 TM-29 TM-30 TM-31 TM-32 TM-33 TM-34 Soyuz-TMA (2002–2012) Soyuz TMA-1 TMA-2 TMA-3 TMA-4 TMA-5 TMA-6 TMA-7 TMA-8 TMA-9 TMA-10 TMA-11 TMA-12 TMA-13 TMA-14 TMA-15 TMA-16 TMA-17 TMA-18 TMA-19 TMA-20 TMA-21 TMA-22 Soyuz-TMA-M (2010–2016) Soyuz TMA-01M TMA-02M TMA-03M TMA-04M TMA-05M TMA-06M TMA-07M TMA-08M TMA-09M TMA-10M TMA-11M TMA-12M TMA-13M TMA-14M TMA-15M TMA-16M TMA-17M TMA-18M TMA-19M TMA-20M Soyuz MS (2016–present) Soyuz MS-01
Uncrewed missions are designated with Kosmos numbers; crewed missions get a Soyuz number. Failed missions are denoted with a † symbol. Cancelled missions are in italics.