Salyut-1 / Салют-1

Salyut 1 (DOS-1) (Russian: Салют-1) was the first space station launched into low Earth orbit by the Soviet Union on April 19, 1971. The Salyut program followed this with five more successful launches of seven more stations. The final module of the program, Zvezda (DOS-8), became the core of the Russian segment of the International Space Station and remains in orbit. Salyut 1 was visited by Soyuz 10 and Soyuz 11. The hard-docking of Soyuz 10 failed and the crew had to abort this mission. The Soyuz 11 crew achieved successful hard docking and performed experiments in Salyut 1 for 23 days. However, they were killed by asphyxia caused by failure of a valve just prior to Earth reentry, and are the only known people to have died above the Kármán line. Salyut 1's mission was later terminated, and it reentered on October 11, 1971.