Soyuz 15 (Russian: Союз 15, Union 15) was a 1974 manned space flight which was to have been the second mission to the SovietUnion's Salyut Space Station with presumably military objectives.
Launched 26 August 1974, the Soyuz spacecraft arrived at the station, but Cosmonaut Lev Dyomin and Gennadi Sarafanov were unable to dock because of a fault in the automated docking system. Without sufficient fuel for prolonged attempts at manual docking, the mission had to be abandoned.The crew landed 28 August. Analysis of the launch window was cited by observers for concluding a flight of 19 to 29 days had been planned.
It was later claimed by Soviet authorities that no docking had been intended and that the flight had been undertaken merely to develop techniques for maneuvering near the space station. They also said that a new automatic docking system was tested which would be used on future Progress transport craft.
In the event of the failure, official TASS statements merely claimed that the mission was intended to practice docking maneuvers with the Salyut 3 station. They also said that a new automatic docking system was tested which would be used on future Progress transport craft.
The failed mission exposed a number of serious design flaws in the Soyuz 7K-T spacecraft, namely its lack of reserve propellant and electrical power for repeated docking attempts. In addition, the Igla docking system was found to be in major need of improvement. Since it was impossible to carry out these changes before Salyut 3 finished its operating lifespan, they had to wait for future space stations. The backup spacecraft for the Soyuz 15 mission was placed in storage and later flown as Soyuz 20 despite being past its intended shelf life.
Soviet-era cosmonauts Gennady Sarafanov and Lev Demin train for their Soyuz 15 spaceflight in 1974. (Roscosmos)
