Thursday, July 6, 2017
Soyuz 21 to Salyut 5 launches 1976
Cosmonauts Boris Volynov (commander) and Vitaly Zholobov (flight engineer) blasted off from Baikonur July 6, 1976 in Soyuz 21 on their way to Salyut 5. Their mission was scheduled to last from 54-66 days, but on August 24, it was announced their mission would end in 10 hours.
No official explanation has ever been found as to why the crew were recalled to Earth so soon. The most likely scenario is an "acrid" odor detected on the space station. Another explanation is Zholobov was in failing health (probably due to nitric acid leaking from the fuel tanks; or the crew did not follow their exercise program and suffered from lack of sleep.
They boarded Soyuz 21 and attempted to detach from Salyut 4, but the mechanism failed to operate properly. They received the first set of emergency instructions right before they lost contact with Russia, due to them moving behind the Earth. Once they regained their signal, they received the emergency procedures and they were able to free themselves from Salyut 5.