Soyuz 18a

Infobox Space mission
mission_name = Soyuz 18
sign = Урал (Ural - "Ural")
crew_members = 2
launch = April 5, 1975 11:04:54 UTC Gagarin's Start
landing = April 5, 1975 11:26:21 UTC Altay Mountains
duration = 00:21:27
orbits = suborbital
next = Soyuz 18
previous = Soyuz 17 |

Soyuz 18a was a Soyuz spacecraft launched by the Soviet Union but which failed to achieve orbit due to a serious malfunction during launch. The crew consisted of commander Vasili Lazarev, an Air Force major, and flight engineer Oleg Makarov (civilian).

The Soyuz 18 mission was supposed to be the second mission to take cosmonauts to the Soviet Salyut 4 space station. Both cosmonauts were on their second mission; they had flown their first mission together, Soyuz 12 in September 1973 to test a new type of Soyuz spacecraft.

The launch proceeded according to plan until T+288.6 seconds at an altitude of 90 miles (145 kilometers), cite book | title= Disasters and Accidents in Manned Space Flight | last= Shayler | first= David | year= 2000 | page= 159 | publisher= Springer Praxis| isbn= 1852332255] when the second and third stages of the booster began separation. Only three of the six locks holding the stages together released, and the third stage's engine ignited with the second stage still attached below it. The third stage's thrust broke the remaining locks, throwing the second stage free but putting the booster under an unanticipated strain that caused it to deviate from the standard trajectory. At T+295 seconds, the deviation became severe enough that the launch escape system automatically separated the Soyuz spacecraft from the third stage booster and then separated the orbital capsule of the spacecraft.

At the time when the safety system initiated separation the spacecraft was already pointed downward toward Earth, which accelerated its descent significantly. Instead of the pre-calculated acceleration in such an emergency situation of 15 "g" (147 m/s²), the cosmonauts experienced up to 21.3 "g" (209 m/s²). Despite very high overloading, however, the landing parachutes opened properly and slowed the craft to a successful landing after a flight of only 21 minutes.

The capsule landed south west of Gorno-Altaisk at a point 515 miles north of the Chinese border. The capsule landed on a snow-covered slope and began rolling downhill towards a 500 foot sheer drop before it was stopped by the parachute becoming snagged on vegetation.cite book | title= Soyuz, A Universal Spacecraft | last= Hall | first= Rex | coauthors= David Shayler | year= 2003 | page= 193 | publisher= Springer Praxis| isbn= 1852336579]

As they had landed in deep snow, the cosmonauts donned their cold-weather survival clothing and Lazarev, fearing they had landed in China, burned papers relating to a military experiment he had been intended to perform in space. Soon, they were in radio contact with a rescue team in an approaching helicopter, who confirmed their landing point was in the Soviet Union, near the town of Aleisk. The snow, the high altitude and the terrain meant the rescuers had great difficulty in making contact with the cosmonauts and it was the next day before they were safely air-lifted out. The crew were returned to Star City in excellent health and the capsule was recovered some time later.

In Brezhnev's time it was rare to disclose anything about Soviet failures, and so the first (Soviet) publication about the realities of the flight was not made until 1983 in the Army newspaper "Red Banner".Fact|date=February 2007

Details about the abort became known in the West much earlier, however, as it occurred during preparations for the joint ASTP mission, and the Soviets had to inform the Americans what had happened. (There was even a U. S. Congressional Inquiry regarding this failure and several others.) It was revealed that the booster used had been an older model than that planned for use for the joint mission that July. In the report the Soviets made to the Americans, the abort was referred to as "the April 5th anomaly"; and as this was the only term the Soviets ever used for the incident, it became the 'official' designation for years afterwards.

The Soyuz 18a flight has been the only case (as of 2006) of a manned booster accident at high altitude. The mission is referred to in the literature as Soyuz 18-1 or Soyuz 18a, since the following Soyuz mission (in May, 1975) received the name Soyuz 18 as the Soviets only gave numbers to successful launches.

The exact landing site of Soyuz 18a had been a subject of debate amongst space historians in subsequent years. A Russian source quoted by James Oberg has stated that the landing occurred in Mongolia. [cite web |url= http://www.jamesoberg.com/soyuz.html |title= Consultant Report: Soyuz Landing Safety|accessdate=2007-12-15 |last= Oberg |first= James |date= March 19, 1997] Other sources have claimed that the capsule came down in China, but both it and the crew were recovered before the Chinese authorities became aware of it.

Crew

Number in parentheses indicates number of spaceflights by each individual prior to and including this mission.
* Vasili Lazarev (2) - Commander
* Oleg Makarov (2) - Flight Engineer

Mission parameters

* Mass: 6830 kg (15,060 lb)

References