The Soviet Union launches Soyuz 33, intended to take cosmonauts Nikolai Rukavishnikov and Georgi Ivanov (the latter of whom is the first Bulgarian space traveler) to space station Salyut 6. But Soyuz 33 never reaches its destination. At a distance of 3,000 feet from Salyut, Soyuz 33’s main engine fails to fire – the first time such a failure has ever occurred in over a decade of Soyuz flights. Soyuz 33 is recalled to Earth at the earliest opportunity, leaving the station crew with no visits from any other human beings during their two-man, 175-day stay in orbit. It is later discovered that Soyuz 33’s engine could have exploded, causing critical damage to the entire vehicle – and ground controllers now focus their attention on Soyuz 32, docked at Salyut with an engine of identical design which could also fail.