The cosmonauts Viktor Patsayev, Georgi Dobrovolsky, and Vladislav Volkov in the Soyuz simulator during their mission training. 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 June 6, 1971, and docked with the first Soviet space station, Salyut 1 the next day. It was the first time a space station was manned. At the end of their mission, the Soyuz 11 crew returned to Earth, but were found dead in the space vehicle after landing. A critical valve in the descent module had been jerked open as Soyuz 11 de-orbited and bled the cosmonauts' air out into space.

Credits - NASA