NO ENTRY FOR THIS FLIGHT
POSSIBLY DUE TO A PERIOD OF REFLECTION OF THE SAD DEATHS OF COSMONAUTS OF SOYUZ 11 ON LANDING AND THE RE-DESIGN OF COMMAND MODULE AND REBUILD OF NEW SPACESTATION

Salyut 2 (OPS-1, military)
Salyut 2 (OPS-1) (Russian Салют-2; English: Salute 2) was launched April 4, 1973. The space station was - despite its "Salyut 2" designation - slated to be the first military space station, part of the highly classified Almaz military space station program - the Salyut designation was chosen to conceal its true nature. Although it launched successfully, within two days the as-yet-unmanned Salyut 2 began losing pressure and its flight control failed; the cause of the failure was likely due to a shrapnel from the discarded and exloded Proton rocket upper stage that pierced the station. Furthermore, on April 11, 1973, 7 days after launch, an unexplainable accident caused four solar panels to be torn loose from the space station cutting off all power. Salyut 2 re-entered on May 28, 1973.

Cosmos 557 (DOS-3)
The module DOS-3 was launched on May 11, 1973 - three days before the launch of Skylab - slated to become next civilian space station with an Salyut designation. 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" - it was revealed to have been a Salyut station only much later. It re-entered Earth's atmosphere a week later, and burned up on re-entry.