Cosmos 573 was an uncrewed test of the redesigned Soyuz vessel. It did not dock with any space station. After the Soyuz 11 disaster the third seat was removed because the space was need for the two crewmen in space suits and their equipment. Cosmos 573 retained its solar arrays.

This is Soyuz's 19th flight, and 11th crewed flight. (modifié!)

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.