A cascading electrical failure
In February 1985, after hosting three cosmonaut crews (including one that stayed for 237 days, a record at the time), the vacant Salyut 7 space station started to experience trouble. Workers in the TsUP (the Soviet version of NASA’s Mission Control) noted that an overcurrent had tripped a circuit breaker, which shut down the station's primary long-range radio transmitter.
Ground controllers switched Salyut 7 to its backup transmitter, which seemed to solve the problem — at least for a bit. However, a subsequent attempt to restart the primary transmitter created another overcurrent that started a cascading series of electrical failures. Both radio transmitters (primary and backup), as well as the station’s radio receivers, ceased to work.
Attempts to revive the station from the ground failed. Salyut 7 went silent. It began to slowly tumble.
Making matters worse, the interior of the station rapidly lost heat, eventually reaching a frigid, yet stable, temperature of about –4 degrees Fahrenheit (–20 degrees Celsius). Soviet engineers realized they had only two options: abandon Salyut 7 or mount a rescue mission.
At this point, the Soviet's larger, more advanced Mir space station was still a work progress. Waiting for Mir to launch would have meant putting all spaceborne work on hold for at least a full year. So, although a crewed rescue mission to Salyut 7 was a dangerous proposition, if successful, the Soviet's would save both time and money — as well as face.
A space rescue begins
The Soviets understood that docking a crewed Soyuz spacecraft with Salyut 7 was a supremely dangerous maneuver. A failed docking could cripple the Soyuz, stranding the crew in orbit, if not killing them outright.
Soviet spacecraft usually depended on an automated docking system, but that relied on computers aboard both vessels being in constant communication with each other. But, in essence, the Soyuz's dance partner was giving it the cold shoulder. Fortunately, cosmonaut Vladimir Dzhanibekov had previously performed a manual docking with the (then-functioning) Salyut 7, which was partly why he was chosen to head the rescue mission; cosmonaut Viktor Savinykh would accompany him.
Dzhanibekov and Savinykh trained extensively on new protocols developed for the planned docking with the lifeless Salyut 7. And on June 6, 1985, the pair launched aboard Soyuz T-13.
During a long, slow approach to the station, Dzhanibekov and Savinykh noticed that Salyut's solar arrays were no longer aligned with each other or the Sun, further confirming the severity of the damage. Fortunately, the station’s rotation rate was manageable. And by using an optical rangefinder, Dzhanibekov manually nestled the Soyuz near Salyut 7, linking the two craft at the forward docking port. “There is a docking!” he triumphantly called out.
Firmly attached to Salyut 7, the cosmonauts' next task was to see if the station could be revived. If they couldn't resurrect Salyut 7 and its systems, they would have no choice but to humbly return to Earth.