Soyuz 6 (Russian Союз 6, Union 6) was part of a joint mission with Soyuz 7 and Soyuz 8 that saw three Soyuz spacecraft in orbit together at the same time, carrying seven cosmonauts. The crew of Gergi Shonin and Valeri Kubasov were meant to take high-quality movie photography of Soyux 7 and Soyuz 8 docking but the rendezvous systems on all three spacecraft failed.

It is still not known exactly what the actual problem was, but it is often quoted as being a helium pressurization integrity test. The version of Soyuz 7K-OK spacecraft used for the missions 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 pressurized with helium to provide a 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.

The crew was made up of Georgi Shonin and Valari Kubasov who carried out important experiments in space welding. They tested three methods: using an electron beam, a low pressure plasma arc and a consumable electrode. The apparatus was designed at the E., Kiev, Ukraine. The weld quality was said to be in no way inferior to that of Earth based welds.

After 80 orbits of the Earth they landed on October 16, 1969, 180 km (110 mi) northwest of Karaganda, Kazakhstan.

The radio call sign of the spacecraft was Antey, referring to the Greek hero Antaeus, but more important, at the time of the flight, however, it was also the name of the largest practicable aircraft, the Soviet Antonov 22, made in Ukraine. But unlike the call signs of Soyuz 7 and Soyuz 8, this was not the name of a squadron in Soviet military training, of uncertain role, for the one that begins with the letter 'a' is Aktif, meaning Active.

Planning the triple Soyuz mission
The active planning for the triple Soyuz mission began immediately after the successful landing of the Soyuz-4 and Soyuz-5 spacecraft in January 1969. The lauchnes were originally scheduled for as early as August 1969 and the crew training started at the end of February, but the crew assignments to the mission had major changes throughout the year.

Campaign - Three Soyuz vehicles prepare to fly
The final launch campaign for the triple Soyuz mission began in Tyuratam on September 22, 1969, with the arrival of the cosmonaut team and the support personnel. Despite the worsening fall weather bringing strong winds and rain to the steppes of Kazakhstan, all three Soyuz spacecraft were ready for launch by the end of the day on October 10, 1969.

Soyuz-6 opens floodgate of launches
The first of the three spacecraft participating in the planned joined mission lifted off on October 11, 1969. The Soyuz-6, carrying no docking port, entered orbit without problems and was in position to monitor the rendezvous of the two subsequent vehicles.

launch - Soyuz-7 joins Soyuz-6 in orbit

On October 12, 1969, the Soyuz-7 spacecraft with Anatoly Filipchenko, Vladimir Volkov and Viktor Gorbatko onboard lifted off from Tyuratam. The successful launch brought for the first time the number of cosmonauts in orbit to five people when counting Georgy Shonin and Valery Kubasov who had reached space around 24 hours earlier aboard Soyuz-6.

soyuz-8
Soyuz-8 completes orbital armada

On October 13, 1969, the Soyuz-8 spacecraft blasted into orbit with Vladimir Shatalov and Aleksei Yeliseev onboard bringing to seven the total number of Soviet cosmonauts in orbit and the number of piloted ships in space to three. The next day, Soyuz-8 was scheduled to dock with Soyuz-7 in view of Soyuz-6, but the last-minute problem interrupted the ambitious scenario.

The mission objectives included:
- checkout and flight test of spaceborne systems and the modified structure of the Soyuz craft,
- further improvement of the control, orientation, and orbital stabilisation systems and navigation aids,
- debugging the piloting systems by orbital maneuvering of the spaceships in relation to one another,
- testing of a system for control of the simultaneous flight of three spacecraft,
- scientific observations and photographing of geological-geographical subjects and exploration of the Earth's atmosphere,