Soyuz 11

Soyuz 11 crew: Viktor Patsayev (top left), Georgi Dobrovolsky (lower left), and Vladislav Volkov (right).

Soyuz 11 was launched on June 6, 1971 with Georgi Dobrovolsky (commander), Vladislav Volkov (flight engineer), and Viktor Patsayev (research engineer).  They became the first crew to live and work on a space station, Salyut 1.  After their experiments were completed they left the station in their Soyuz spacecraft for their return to earth.  A valve opened, caused by the vibrations of the separation the descent module from the orbital module (the two pressurized modules of a Soyuz spacecraft) before re-entry.  This valve is designed to open after landing to equalize pressure inside the cabin with the outside.  It is believed that the crew died within 45 seconds.   Patsayev was found with a bruised hand which may have been caused from his attempt to manually close the valve, which is a lengthy procedure.  Ground controllers were unaware of any trouble until they opened the hatch of Soyuz 11, only to find the three cosmonauts had died.