Full Video of State Funeral of the Soyuz 11 Cosmonauts, Lieutenant General Georgy Dobrovolsky, Engineers Viktor Patsayev and Vladislav Volkov
It was discovered that a valve had opened just before leaving orbit that had allowed the capsule's atmosphere to vent away into space, causing the Cosmonauts to suffer fatal hypoxia as their cabin descended toward the Earth's atmosphere. They were the only three people died in outer space, Dobrovolsky aged 43, Patsayev aged 38 and Volkov aged 35