Soyuz 7K-T No.39 (also named Soyuz 18a or Soyuz 18-1 by some sources and also known as the April 5 Anomaly)
The accident was partly disclosed by the normally secretive Soviets as it occurred during preparations for their joint Apollo-Soyuz Test Project with the United States which flew three months later. Lazarev never flew to space again and never fully recovered from the accident; Makarov made two more flights on board a Soyuz (both of which were to the Salyut 6 space station).
Crew
Backup crew
Mission highlights
Soyuz 7K-T No.39 was intended to be the second mission to take cosmonauts to the Soviet Salyut 4 space station for a 60-day mission. 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 unexpected strain that caused it to deviate from the proper trajectory. At T+295 seconds, the deviation was detected by the Soyuz's guidance system, which activated an automatic abort program. As the escape tower was long gone by this point, the abort had to be performed with the Soyuz's own engines. This separated the spacecraft from the third-stage booster and then separated the orbital and service modules of the Soyuz from the re-entry capsule. 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 expected acceleration in such an emergency situation of , the cosmonauts experienced up to . Having landed in chest-deep powder snow and a local temperature of , the cosmonauts donned their cold-weather survival clothing. The cosmonauts were uncertain if they had landed in China, at a time when Sino-Soviet relations were extremely hostile, so they quickly destroyed documents relating to a military experiment planned for the flight. The Americans were informed on 7 April 1975 after the crew had been rescued. However, as the failure occurred during preparations for the joint Apollo-Soyuz Test Project, the United States requested that a more detailed report of the accident be provided. (There was even a United States congressional inquiry regarding this failure and several others.) 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, that became the "official" designation for years afterwards. It was also disclosed that the booster used in the launch was an older model and not the same model that would be used for Soyuz 19. The mission is referred to in some literature as Soyuz 18a or Soyuz 18-1, since the following Soyuz mission in May 1975 received the name Soyuz 18. (The Soviets only gave numbers to successful launches.)
The exact landing site of the capsule was 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.
The failed Soyuz mission was the only case of a crewed booster accident at high altitude until the accident with Soyuz MS-10 on 11 October 2018.
Mission parameters
- Mass:
- Apogee:
See also
- Soyuz 7K-ST No.16L, 1983 Soyuz launch failure
- Soyuz MS-10, 2018 in-flight failure
- List of spaceflight-related accidents and incidents