Date: 6 June 1971
Time: 04:55:09 UTC
Date: 29 June 1971
Time: 23:16:52 UTC
Location: 47° 21.4' N, 70° 7.3' E
Salyut, 7 June 1971 07:49 UTC - 29 June 1971 18:28 UTC
Duration: 23 days, 18 hours, 21 minutes, 43 seconds
Call Sign: Yantar (Amber)
The backup crew of Leonov, Kubasov, and Kolodin were originally the prime crew. Kubasov developed a medical problem two days before launch, and the original backup crew of Dobrovolsky, Volkov, and Patsayev became the flight crew.
This was the only mission to successfully use the Salyut 1 station. The crew performed various scientific experiments during their stay. There were rumors that the mission was cut short due to various problems aboard the station, including an electrical fire.
During the reentry maneuver, the reentry and orbital modules were to be separated by a dozen pyrotechnic devices. These devices all fired simultaneously instead of sequentially. This caused a low altitude pressure equalization valve to prematurely open at an altitude of 168 km. The capsule depressurized in about 30 seconds. Manually closing this valve was a procedure that took about 60 seconds. The crew, who were not wearing pressure suits, managed to close the valve about half way before they lost consciousness and died. Thereafter, pressure suits were worn during reentries.
A memorial to the crew of Soyuz 11.