Soyuz 7 launched
October 12, 1969, one spacecraft of the an
ambitious three spacecraft mission. Soyuz 7 was to dock with
Soyuz 8 while
Soyuz 6 made
spectacular film of the linkup nearby. However this never took place as none of the spacecraft were able to
dock due to the failure of all their rendezvous systems.
The crew on board were commander Anatoli Filipchenko, flight-engineer Vladislav Volkov and research-cosmonaut Viktor Gorbatko. Their callsign through the mission was Buran (Snowstorm).
It is still not quite known exactly what the actual problem was but it is often quoted as being a helium pressurisation integrity test. The version of Soyuz spacecraft used for the missions (7K-OK) carried a torus shaped docking electronics equipment housing surrounding the motor assembly on the back of the service module. This is thought to have been pressurised with helium to provide a nice benign environment for the electronics. It was then jettisoned after docking to lower the mass of the spacecraft for reentry. What went wrong with the electronics on all three spacecraft is still not known.
There were some claims that in fact docking was not actually an objective on these flights but it then seems strange that they carried the docking apparatus and the crew of Soyuz 8 were veterans of a successful docking mission. And the fact that Soyuz 7 and 8 managed to come within 500 metres of each other it would seem stupid to not to have planned to dock.
According the the Soviet sources the other objectives for the mission were: testing spacecraft systems and designs, manoeuvring of spacecraft with respect to each other in orbit, conducted scientific, technical and medico-biological experiments in group flight.
They landed after a 4 day mission on October 17, 1969, landing 155 km northwest of Karaganda, Kazakhstan.
Sources
http://www.astronautix.com
http://planet4589.org/
http://www.spacefacts.de