Soyuz 11: Disaster in Space

Soyuz 11
A TASS/Soviet Space agency image of the three Soyuz 11 astronauts in training for their ill-fated mission. TASS

After the Americans landed Apollo 11 on July 20, 1969, the Soviets officially lost the race for the Moon. Now, they turned their attention towards constructing space stations, a task they became quite good at, but not without problems. 

The first space station to ever be built was called Salyut 1 and was launched on April 19, 1971. It was the earliest predecessor for the later Skylab and International Space Station missions.

The Soviets built Salyut 1 primarily to study the effects of long-term space flight on humans, plants, and for meteorological research. It also included a spectogram telescope, Orion 1, and gamma ray telescope Anna III. Both were used for astronomical studies.

A Troubled Beginning

Salyut 1’s first crew launched aboard Soyuz 10 on April 22, 1971. Cosmonauts Vladimir Shatalov, Alexei Yeliseyev and Nikolai Rukavishnikov were aboard. When they reached the station and attempted to dock on April 24, the hatch would not open. After making a second attempt, the mission was cancelled and the crew returned home. Problems occurred during reentry and the ship’s air supply became toxic. Nikolai Rukavishnikov passed out, but he and the other two men recovered fully.

The next Salyut crew, scheduled to launch aboard Soyuz 11, were three experienced fliers: Valery Kubasov, Alexei Leonov and Pyotr Kolodin. Prior to launch, Kubasov was suspected of having contracted tuberculosis, which caused the Soviet space authorities to replace this crew with their backups, Georgi Dobrovolski, Vladislav Volkov and Viktor Patsayev, who launched on June 6, 1971.

A Successful Docking

After the docking problems that Soyuz 10 experienced, the Soyuz 11 crew used automated systems to maneuver within 100 meters of the station, then hand-docked their ship. However, problems plagued this mission, too. The primary instrument aboard the station, the Orion telescope, would not function because its cover failed to jettison.

The cramped working conditions and a personality clash between the commander Dobrovolskiy (a rookie) and the veteran Volkov made it very difficult to conduct the planned experiments. After a small fire flared up, the mission was cut short and the astronauts departed after 24 days, instead of the planned 30. Despite these problems, the mission was still considered a success.

Disaster Strikes

Shortly after Soyuz 11 undocked and made an initial retro fire, communication was lost with the crew far earlier than normal. The capsule descended and made a soft landing. It was recovered on June 29, 1971 23:17 GMT. When the hatch was opened, rescue personnel found all three crew members were dead.  What could have happened?

Any space tragedy requires thorough investigation so that mission planners can understand what happened and why. In this case, the Soviet space agency mounted a full inquiry. Its investigation showed that a valve which was not supposed to open until an altitude of 4 km was reached had been jerked open during the undocking maneuver. This caused the cosmonauts' oxygen to bleed out to space. The crew tried to close the valve, but ran out of time. Due to space limitations, they were not wearing space suits.

The official Soviet document on the accident explained more fully: 

"At approximately 723 seconds after retrofire, the 12 Soyuz pyro cartridges fired simultaneously instead of sequentially to separate the two modules .... the force of the discharge caused the internal mechanism of the pressure equalization valve to release a seal that was usually discarded pyrotechnically much later to adjust the cabin pressure automatically. When the valve opened at a height of 168 kilometers the gradual but steady loss of pressure was fatal to the crew within about 30 seconds. By 935 seconds after retrofire, the cabin pressure had dropped to zero....... ...only thorough analysis of telemetry records of the attitude control system thruster firings that had been made to counteract the force of the escaping gases and through the pyrotechnic powder traces found in the throat of the pressure equalization valve were Soviet specialists able to determine that the valve had malfunctioned and had been the sole cause of the deaths."

The End of Salyut

The USSR did not send any other crews to Salyut 1. It was later deorbited and burned up on reentry. Later crews were limited to two men, to allow room for the required space suits during take-off and landing. It was a bitter lesson in spacecraft design and safety, for which three men paid with their lives. 

Edited and updated by Carolyn Collins Petersen.