At the end of their mission aboard Soyuz 11, cosmonauts Viktor Patsayev, Georgi
Dobrovolsky, and Vladislav Volkov fired the explosive bolts to separate the
re-entry capsule from the other stage of their spacecraft. The explosion
knocked open a valve. One hundred miles above the Earth, the capsule was
suddenly exposed to the surrounding low pressure of space. Patsayev tried to
close the valve by hand but failed. Air inside the spacecraft quickly leaked
away, causing an abrupt loss of pressure and the death of all three
Soyuz 11 crash site: rescuers giving CPR to cosmonauts.