Viktor Patsayev

Viktor Ivanovich Patsayev (; 19 June 193330 June 1971) was a Soviet cosmonaut who flew on the Soyuz 11 mission and was part of the third space crew to die during a space flight. On board the space station Salyut 1 he operated the Orion 1 Space Observatory (see Orion 1 and Orion 2 Space Observatories); he became the first man to operate a telescope outside the Earth's atmosphere.

After a normal re-entry, the capsule was opened and the crew was found dead. It was discovered that a valve had opened just prior to leaving orbit that had allowed the capsule's atmosphere to vent away into space, suffocating the crew. One of Patsayev's hands was found to be bruised, and he may have been trying to shut the valve manually at the time he lost consciousness.

Patsayev's ashes were interred in the Kremlin Wall on Red Square in Moscow. He was posthumously awarded the title of Hero of the Soviet Union, the Order of Lenin and the title of Pilot-Cosmonaut of the USSR. The lunar crater Patsaev and the minor planet 1791 Patsayev are named for him. A plaque accompanying the Fallen Astronaut, a sculpture by Paul Van Hoeydonck placed on the Moon by David Scott during the 1971 Apollo 15 mission, lists Patsayev's name.