Cosmos 557 topic

The Salyut space station that Almaz had substituted for, designated DOS 3, was launched on May 11, 1973, three days before the launch of Skylab. Due to errors in the flight control system while out of the range of ground control, the station fired its orbit-correction engines until it consumed all of its fuel. Since the spacecraft was already in orbit and had been registered by Western radar, the Soviets disguised the launch as "Cosmos 557" and quietly allowed it to reenter Earth's atmosphere... full article at wikipedia