Salyut 6 EP-5-1
AKA: Salyut 6 EP-5-1;Saturn (Saturn). Launched: 1979-04-10. Returned: 1979-04-12. Number crew: 2 . Duration: 1.96 days.
Flight under the Intercosmos program of an international team consisting of N N Rukavishnikov (USSR) and G I Ivanov (Bulgaria). Unsuccessful mission. Failed to rendezvous with Salyut 6. Recovered April 12, 1979 16:35 GMT.
Narrative (adapted from D S F Portree's Mir Hardware Heritage, NASA RP-1357, 1995)
The problems began when Soyuz 33 fired its main engine while closing to within 4 km of the station. The burn, the sixth of the flight, was to have lasted 6 seconds, but the engine shut down after 3 seconds. The Igla docking system also failed. The EO-3 crew aboard Salyut 6 reported flames shooting sideways from the main engine, toward the backup engine, at the time of the shutdown. The docking was called off and the Soyuz 33 crew conducted a to return to Earth using the backup engine. The engine fired but did not shut off at the end of the planned 188-sec burn. Rukavishnikov, uncertain if the engine operated at the proper thrust, let it burn an additional 25 sec before shutting it down manually. As a result, Soyuz 33 made a steep ballistic reentry with gravity loads up to 10 g's. Because the service module was discarded after deorbit burn, examination of the failed engine was impossible. The Soyuz 33 crew was to have traded its spacecraft for Soyuz 32. Still uncertain of the reliability of the Soyuz, Soyuz 34 was launched unmanned to the station to provide the crew with a fresh lifeboat.