Soyuz 11

By Neon Ngo

The Mission

Soyuz 11 was the second mission to Salyut 1, the first civilian space station. The first mission, Soyuz 10, was aborted because the crew could not enter the space station. The cosmonauts Viktor Patsayev, Georgi Dobrovolsky, and Vladislav Volkov were the crew of Soyuz 11. Originally, they were the Soyuz 11 backup crew, but when Valery Kubasov from the original crew became ill, the crews were changed. Soyuz 11 was launched on the 6th of June, 1971, and docked Salyut 1 the following day. This mission mark the first time a space station was manned.

The joined configuration of Soyuz and Salyut was 21.4 meters long with a total living space of 100 cubic meters, which gave the cosmonauts a place to conduct scientific experiments, relax, and sleep. For the next 23 days, each crewmember performed his scheduled experiments, which emphasized the study of human performance under, and reaction to, prolonged weightlessness. Research in the areas of astronomy, biology, and Earth observation were also done. This record-breaking 24-day space mission was heralded as the beginning a new era in space exploration

Crew of Soyuz 11

The Tragedy

On June 29, 1971 the three cosmonauts boarded the Soyuz 11 command module, for their return flight home to earth after completing their flight plan successfully. They had previously transferred their scientific records, film, and log books to Soyuz in preparation for their return home. Everything went as planned, until the craft began to enter the Earth's atmosphere. A failure in the firing of the pyrotechnic devices that separate the Soyuz orbital module from the return module caused a pressure equalization valve to remain open and thus allowed the atmosphere in the return module to leak out. The cabin began to lose pressure, and oxygen. Viktor, one of the cosmonauts, knew that in order to restore pressure, he had to close the pressure equalization valve. He began turning the handle connected to the valve as fast as he could, but unfortunately, it was not fast enough. He was only able to get the valve half closed, when he died from lack of oxygen.

The spacecraft landed successfully, but the recovery teams found all three cosmonauts dead. As a result of this accident, all subsequent Soyuz crews have worn pressure suits during launch, re-entry, and docking activities. The Soviet Union did not return any crews to Salyut 1 and it was more than two years before they attempted another manned mission. The accident was a stunning blow to both the Soviet Union and the international aerospace community. The experimental and risky nature of man's venture into space had been made clear.

Concluding Remarks

If the design had done a better job on the valve, the cosmonaut would have been able to close it in time. However, when designing the valve, the conditions under which it would be needed to be closed were not considered. It was intended to be used for such an emergency, however when the emergency came, it was not possible to close the valve in time to save the crew's lives, hence defeating its purpose.

In a case like this, the design team should have done more testing. However, it would be difficult to simulate the exact conditions of space, while still on Earth. The engineers didn't know what to include in the design until something actually happened, and by that time it was too late. This is the huge problem that faces the individuals designing safety-critical systems. If they knew every single condition then they could make their design handle it. But, unfortunately that is not reality.


Last revised on Dec. 7, 1997 by Neon Ngo in partial fulfillment of the requirements of CS 3604, Fall 1997.