Backup crew

Mission parameters

• Mass: 6860 kg (15,123.7 lb)
• Perigee: 198.6 km (123.4 mi)
• Apogee: 279.2 km (173.5 mi)
• Inclination: 51.63°
• Period: 88.99 minutes

Mission highlights

After a two-day delay caused by a windstorm at the launch site, Soyuz 33 was launched 10 April 1979 with the fourth international crew in the Soviet Intercosmos

Intercosmos

Interkosmos was a space program of the Soviet Union designed to include members of military forces of allied Warsaw Pact countries in manned and unmanned missions...

 program. Bulgaria

Bulgaria

Bulgaria , officially the Republic of Bulgaria , is a parliamentary democracy within a unitary constitutional republic in Southeast Europe. The country borders Romania to the north, Serbia and Macedonia to the west, Greece and Turkey to the south, as well as the Black Sea to the east...

n cosmonaut Georgi Ivanov

Georgi Ivanov

Major general Georgi Ivanov Kakalov is a retired Bulgarian military officer and the first Bulgarian cosmonaut. He was a member of the National Assembly of Bulgaria in 1990.-Early life and military career:...

 joined commander Nikolai Rukavishnikov

Nikolai Rukavishnikov

|Nikolai Nikolayevich Rukavishnikov was a Soviet cosmonaut who flew three space missions of the Soyuz programme: Soyuz 10, Soyuz 16, and Soyuz 33...

 as the craft proceeded normally towards the Salyut 6 space station.

Rukavishnikov was the first civilian to command a Soviet spacecraft, and Ivanov the first Bulgarian in space.

At 9 km distance from the station, the Igla automatic docking system was activated. But, as the craft approached to 1,000 metres, the engine failed and automatically shut down after three seconds of a planned six-second burn. Rukavishnikov had to hold the instrument panel as the craft shook so violently. After consulting with ground control, the docking system was activated again, but the engine shut down again, and Valery Ryumin

Valery Ryumin

Valery Victorovich Ryumin, born August 16, 1939 in Komsomolsk-on-Amur) is a former Soviet cosmonaut.In 1958, he was graduated from the Kaliningrad Mechanical Engineering Technical College with the specialty "Cold Working of Metal." In 1966, he was graduated from the Department of Electronics and...

, observing from the station, reported an abnormal lateral glow from behind the Soyuz during the burn. Mission control accordingly aborted the mission and told the crew to prepare to return to earth. It was the first in-orbit failure of the Soyuz propulsion system.

The failure was determined to be a malfunction of the main engine. A pressure sensor in the combustion chamber was shutting down the engine when it seemed normal combustion pressure was not being reached. This shut-down mechanism was designed to prevent propellants from being pumped into a damaged engine thus risking damage and/or an explosion.

The crew requested another attempt at an engine burn, but were denied and told to sleep. A recovery attempt could not be made for another day. Rukavishnikov couldn't sleep, however, and thought about the book Marooned

Marooned (novel)

Marooned is a 1964 science fiction thriller novel by Martin Caidin, about a manned spacecraft which becomes stranded in Earth orbit, oxygen running out, and only an experimental craft available to attempt a rescue...

 which featured an American

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 space crew stranded in orbit.

It was only in 1983 that the Soviets revealed how serious the situation was. The craft had a back-up engine but it was feared that it may have been damaged by the main engine, potentially leaving the crew stranded with five days of supplies while it would take ten days for the orbit to decay. One option to return the crew if the backup engine was inoperable would have been to use attitude control thrusters to slow the Soyuz below orbit velocity. But there may have not been enough propellant to do this, and the landing point would have been unpredictable if it worked. Another option was to move the station to the Soyuz. The station could have been moved to within 1,000 m of the craft, at which point Soyuz 33 could be docked using its thrusters. But the two crafts were drifting apart at 28 metres per second, and time was needed to calculate the maneuvers. In any event, four crew on the station with one malfunctioning Soyuz and a second Soyuz (the station crew's Soyuz 32

Soyuz 32

-Backup crew:-Mission parameters:*Mass: *Perigee: *Apogee: *Inclination: 51.61°*Period: 89.94 minutes-Launch and station activation:...

, already docked at Salyut 6) with a now-questionable engine (it had the same type as Soyuz 33) was not considered the best option.

The main option was to fire the back-up engine, but this option was not guaranteed to work, even if the engine fired. The nominal burn time was 188 seconds, and as long as the burn lasted more than 90 seconds, the crew could manually restart the engine to compensate. But this would mean an inaccurate landing. If, however, the burn was less than 90 seconds, the crew could be stranded in orbit. A burn longer than 188 seconds could result in too-high loads on the crew during re-entry.

In the end, the backup engine did fire, though for 213 seconds, 25 seconds too long, resulting in an unusually steep trajectory and loads of 10 G's to be endured by the crew. Rukavishnikov and Ivanov were safely recovered. It was the second ballistic entry reported by the Soviets, Soyuz 1

Soyuz 1

Soyuz 1 was a manned spaceflight of the Soviet space program. Launched into orbit on April 23, 1967 carrying cosmonaut Colonel Vladimir Komarov, Soyuz 1 was the first flight of the Soyuz spacecraft...

 being the first. Others noted that Soyuz 18a

Soyuz 18a

Soyuz 18a was a manned Soyuz spacecraft launched by the Soviet Union in 1975, intended to dock with the orbiting Salyut 4 space station, but which failed to achieve orbit due to a serious malfunction during launch...

 was a ballistic reentry, and Soyuz 24

Soyuz 24

Soyuz 24 was a 1977 Soviet mission to the Salyut 5 space station, the third and final mission to the station, the last purely military crew for the Soviets and the final mission to a military Salyut...

 reportedly also was one.

An investigation lasted a month and found that the part that failed had been tested 8,000 times previously without failing, and the Soyuz engine had fired some 2,000 times since 1967, also without a single failure. But the engine was modified for the next flight, and a vacant Soyuz with the newly modified engine, Soyuz 34

Soyuz 34

Soyuz 34 was a 1979 Soviet unmanned space flight to the Salyut 6 space station. It was sent to supply the resident crew a reliable return vehicle after the previous flight, Soyuz 33, suffered an engine failure....

, was sent to the orbiting Salyut for the crew there to return with.

External links

• Soyuz 33 chronology at videocosmos.com