Figure 14.6-1. Patsayev, Dobrovolsky and Volkov in the Soyuz simulator during training.
These three Soviet cosmonauts had completed successfully the first visit to Salyut 1, the first space station in the history of spaceflight, and were beginning their maneuvers for reentry on June 30, 1971, when the cabin of their Soyuz 11 spacecraft depressurized in a few seconds due to a damaged valve at an altitude of 168 kilometers (551,000 feet).
The valve was out of reach and the cosmonauts were not wearing pressure suits due to the tightness of the cabin and therefore died by suffocation. Dobrovolski was 43; Patsayev was 38; Volkov was 35. Their ashes are in the Kremlin, in Moscow.