Soyuz 12 was launched September 27, 1973, nearly two years after the fatal Soyuz 11 flight. The objective of Soyuz 12 was to test the new Soyuz 7K-T spacecraft that had been designed to fix the problems that had occurred in the previous model.

On board were cosmonauts Vasili Lazarev and Oleg Makarov. Their callsign was Ural (Urals).

The flight was short at only two days and was the third flight of the spacecraft which had already flown unmanned on Cosmos 496, flown June 26 to July 2, 1972, and Cosmos 573, flown Juune 15 to 17, 1973.

The biggest difference between the 7K-T and the older Soyuz was the fact that the crew wore spacesuits. This was accomplished by eliminating a crew position. It was also decided to replace the solar panels with batteries. Although this limited the autonomous lifespan of the Soyuz to two days, it lowered the weight of the spacecraft. They also redesigned the valve and seal that had come loose on Soyuz 11, improved the manual valve closing so that it took fewer turns of the handle to close it, reduced the power of the pyrotechnic bolts and replaced half of them with pyrotechnic/gas actuated latches, and provided for the crewmen to reenter in pressure suits.

Although most of the mission was taken up with testing the systems of the newly improved Soyuz, the crew did get a chance to do some spectroscopic observations of the Earth.

They landed 400 km southwest of Karaganda, Kazakhstan on September 29.

  • SP-4209 The Partnership: A History of the Apollo-Soyuz Test Project available at