On April 23, 1971, the manned spacecraft “Soyuz-10“ , which is to dock with the world's first habitable orbital space station “ Salyut 1“, launched into orbit on April 19, 1971. But due to damage, the docking failed and the crew returned to Earth, BTA recalls.
A new attempt has been made. The crew of “Soyuz-11" composed of: Alexey Leonov (commander), Valery Kubasov and Pyotr Kolodin, has the task of docking with the station and conducting a number of scientific research and experiments in it. Before the start, the medical commission forbids Valery Kubasov to fly because of a lung problem. This necessitated at the last moment the main crew to be replaced by the backup crew: Georgy Dobrovolskyi (commander), Vladislav Volkov and Viktor Patsaev.
On June 6, 1971, the manned transport spacecraft “Soyuz-11" was launched from Baikonur.
After successful docking with the orbital station, the astronauts work on it for 22 days. Regardless of all the difficulties, they fully fulfill the flight program.
On June 30, 1971, the ship landed in Kazakhstan. But when air traffic control tries to make contact, no one answers the radio calls. After the ground crews arrived at the landing site, they found that all three astronauts were dead.
The investigation found that while “Soyuz-11" is in the upper layers of the atmosphere, at a height of more than 100 kilometers, descending to Earth, one of the valves opens and depressurization of the capsule occurs. The pressure drops sharply and the astronauts die from explosive decompression.
Dobrovolsky, Volkov and Patsaev would have survived if they were in spacesuits, but their use was discontinued in 1964 to save space. The decision turns out to be fatal.
The tragedy shocked not only the USSR, but also the whole world. It is hypothesized that the cosmonauts' bodies could not withstand the stress of entering the Earth's atmosphere after the long-term stay in a state of weightlessness. The flight is the longest so far. For 23 days 18 hours 21 minutes and 43 seconds “Soyuz-11” makes 368 rounds of the Earth.
For the next few years, flight crews consist of two cosmonauts, and everyone takes off and lands in spacesuits.
For the first time since “Soyuz-11“ only in 1980 the ship had a crew of three.
After June 30, 1971, there were no accidents with human casualties in the Soviet-Russian cosmonautics.