Forty years ago today — June 6, 1971 — Soyuz-11 launched from the Baikonur Cosmodrome, carrying the first crew to the USSR’s Salyut-1 space station.
The Soyuz-11 crew, cosmonauts Georgi T. Dobrovolskiy, Vladislav N. Volkov and Viktor I. Patseyev, spent three weeks aboard Salyut. Their separation from Salyut-1 on June 30th was nominal, and before they entered the atmosphere the service module of the Soyuz vehicle detached from the descent module; however, as reported on this Wikipedia page, a pressure equalization valve failed and the crew asphyxiated before their vehicle reached the ground.
Here’s a link to a July 1971 Time Magazine article about the Soyuz-11 disaster: Triumph and Tragedy of Soyuz-11.
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