Soyuz 11

Lore & Background

The original prime crew for Soyuz 11 consisted of Alexei Leonov, Valery Kubasov, and Pyotr Kolodin. A medical X-ray examination four days before launch suggested that Kubasov might have tuberculosis, and according to the mission rules, the prime crew was replaced with the backup crew. For Dobrovolsky and Patsayev, this was to be their first space mission. After the Soyuz 11 tragedy, Kubasov and Leonov were reassigned to Soyuz 19 for the Apollo-Soyuz Test Project in 1975.

Soyuz 11 successfully docked with Salyut 1 on 7 June 1971 and the cosmonauts remained on board for 22 days, setting space endurance records that would hold until the American Skylab 2 mission in May and June 1973. Upon first entering the station, the crew encountered a smoky and burnt atmosphere, and after replacing part of the ventilation system, spent the next day back in their Soyuz until the air cleared. A fire broke out on day 11 of their stay, causing mission planners to consider abandoning the station.

On 29 June 1971, the three cosmonauts loaded scientific specimens, films, tapes, and other gear into Soyuz 11, then transferred manual control back from Salyut 1 to Soyuz 11 and returned to their ferry craft. During re-entry preparations, a breathing ventilation valve jolted open as the descent module separated from the service module, causing fatal depressurisation. The crew died within about 40 seconds. Patsayev's body was found positioned near the valve, and he may have been attempting to close or block the valve at the time he lost consciousness.

Reader's Guide

Soyuz 11 remains the only spaceflight in which humans have died above the Kármán line, making it a pivotal tragedy in space exploration history. The mission demonstrated both the potential and the peril of long-duration stays aboard space stations, as the crew set endurance records that stood for two years. The accident led to design changes in Soyuz spacecraft, including requiring crews to wear pressure suits during launch and re-entry. The Soviet state initially withheld the cause of death for nearly two years, causing concern among U.S. space planners about the safety of prolonged weightlessness. The disaster underscored the critical importance of redundant safety systems and emergency procedures in human spaceflight.

Did You Know?

• The original prime crew for Soyuz 11 was replaced four days before launch because a medical X-ray suggested Valery Kubasov might have tuberculosis.
• A fire broke out on day 11 of the crew's stay aboard Salyut 1, causing mission planners to consider abandoning the station.
• The crew members of Soyuz 11 are the only humans to have died in space (i.e. above the Kármán line).
• Patsayev's body was found positioned near the valve that caused the depressurisation, suggesting he may have tried to close it.