Soyuz 8 was part of a joint mission with Soyuz 6 and Soyuz 7 that saw three Soyuz spacecraft in orbit together at the same time, carrying a total of seven cosmonauts.
The crew consisted of commander Vladimir Shatalov and flight engineer Aleksei Yeliseyev, whose mission was to dock with Soyuz 7 and transfer crew, as the Soyuz 4 (involving, among others, these two cosmonauts) and Soyuz 5 missions did. Soyuz 6 was to film the operation from nearby.

However, this objective was not achieved due to equipment failures. Soviet sources were later to claim that no docking had been intended, but this seems unlikely, given the docking adapters carried by the spacecraft, and the fact that both Shatalov and Yeliseyev were veterans of the previous successful docking mission. This was the last time that the Soviet-crewed Moon landing hardware was tested in orbit, and the failure seems to have been one of the final nails in the coffin of the programme.

This is Soyuz's 14th flight, and 7th crewed flight.

The Soyuz is a Soviet crewed spaceship, developed to made manned lunar missions. This version called 7K will fly 4 times on the giant launcher N1, and several tens of times on Proton to fly over the Moon, which will be successful during the mission Zond 4. Soyuz will become the first spacecraft to transport living beings to the Moon during the flight of Zond 5, with two turtles. Subsequently, it is adapted to low orbit and will fly on the Soyuz launcher to serve the Salyut and Mir stations and the ISS.