Soyuz 16 was launched December 2, 1974
. It was the first manned test flight of the Soyuz ASTP
spacecraft. The crew checked out the modernised systems on board the spacecraft, which was also tracked by the USA
On board were Anatoli Filipchenko and Nikolai Rukavishnikov, who were also on the backup crew for the actual ASTP flight, Soyuz 19. Their callsign for the mission was Buran (Snowstorm).
The Russians had agreed to notify NASA of the impending launch 5 days before liftoff. However NASA were not allowed to inform the media of this before the actual launch. NASA could not agree to this due to their policy of never withholding anything from the press. So it was decided that they would receive notification at the same time that the rest of the world were informed of the launch by the Soviets.
The Soyuz spacecraft was intially put into a higher orbit than that planned for the Soyuz 19 flight. The Soviets announced that this was in order to demonstrate the manoeuvrability of the modernised spacecraft. There is a some speculation that there was a a trajectory error during launch. Of course it does not matter which of these two it was as the higher orbit showed that the Russians could recover from a potentially mission ending problem.
An important test was of the new environmental systems. The Apollo spacecraft used pure oxygen at about a third of atmospheric pressure. However the Soyuz used a nitrogen/oxygen mixture at one atmosphere. This would cause problems for the crew transfering between the two spacecraft as they would suffer from the 'bends'.
To stop this occurring the astronauts and cosmonauts would spend time in the Docking Module that would join the Apollo and Soyuz. This would slowing change the atmosphere over a couple of hours. As well as this the Soyuz would lower its atmospheric pressure, shortening the amount of time prebreathing before entering either spacecraft. Over the first few days of the Soyuz 16 mission the atmosphere was lowered and raised.
The crew also tested the new androgonous docking system. This was to be used for the first time on the ASTP flight. On Soyuz 16, an apparatus had been designed that mimicked the actions of the Apollo docking ring. This was used to test the operation of the Soyuz side. They even tested the emergency release system in case either spacecraft had to make an immediate return to Earth (like in the case of a depressurisation).
After a nearly six day mission the spacecraft landed 300 km north of Dzheskasgan, Kazakhstan on December 8.
The mission even gave the Soviet authorities a chance to test the new public affairs procedures for ASTP. For the first time the press were able to ask questions of the crew directly and visit Star City, just outside of Moscow where the cosmonauts trained (the equivalent of the Johnson Space Center in the USA).
The crew, who were veterans from previous Soyuz flights, commented that the changes to the spacecraft made it a more flexible ship to fly.