salyut 7; the rescue of a derelict space station

A little background on the topic

The Salyut 7 was a space station hanging out in low earth orbit. It was the seventh and final iteration of the Soviet space program's "Salyut programme". It was launched on April 19 1982 at 19:45:00 UTC from the Baikonur Cosmodrome in Kazakhstan with an initial launch mass of 19,824 kg.

Trouble in paradise

It was business as usual for the Salyut 7 up until Feb 11, 1985. That day the primary long-range radio went completely dark due to an (at the time) unknown cause. Right after this TsUP (Russian equivalent of ground control) got to work and managed to re-establish contact with the station through its secondary (and less powerful) radio. To their shock this only ended up lasting for several tens of minutes, until that too, went completely dark. In the end the engineers were faced with nothing but a static crackle and a ghost space station weighing 20 metric tonnes tumbling around earth with no telemetry or radio. And the absolute cherry on top? The station was losing orbit. If nothing was done, the station would be lost to the laws of thermodynamics.

Arduous decision

As the reality began to dawn upon the Soviets they had to weigh the risks. The challenges and risks with staging a rescue mission were not trivial; The only realistic shot they had at a rescue was to manually dock a crewed Soyuz spacecraft with the Salyut 7.

Under regular circumstances a docking was performed by automated computer systems being in constant communication with each other. This was already difficult enough. The risks of a manual docking maneuver were grave indeed; a single wrong move could cripple the entire manned Soyuz craft and leave it stranded in orbit, left to die.

However, of course, in true Soviet fashion; after a thorough feasibility assessment a formal operational commitment and crew formation was made 35 days later, on 18 March 1985. Chosen for this mission were Vladimir Dzhanibekov, who had a history with manually docking the (then fully functional) Salyut 7, along with Viktor Savinykh who had previously spent 74 days aboard the Salyut 6.

Running the gauntlet

The rescue mission officially started on 6 June 1985, the crewed Soyuz T-13 craft was launched from Baikonur at 6:39 UTC. The crew got the first visual sighting of the Salyut 7 48 hours and 20 minutes after launch on 8 June 07:00 UTC. The Soyuz's automated systems could get them within a range of ~2kms. From that point onwards, Savinykh tracked the Salyut 7 using the optical sight and a handheld laser rangefinder. They kept a constant visual through their window with the craft, Savinykh kept calling out the relative motion and distance as Dzhanibekov was manually piloting it ever closer. They managed to align Soyuz's rotation with that of the Salyut. Once aligned Dzhanibekov slowly crawled in and manually managed to hard dock the craft successfully 1 hour and 50 minutes after the initial sighting of Salyut 7 at 08:50 UTC. This is widely considered to be one of the most difficult docking maneuvers ever performed.

Let there be light

Now that they had managed to dock their Soyuz T-13 spacecraft with the Salyut 7 space-station, the two cosmonauts began making their way in. The crew started off by slowly opening the side hatch, carefully listening for any leaks and slowly equalizing the pressure between the two craft. Once finalized, Dzhanibekov was the first to take a peek inside of the derelict station, and he immediately noticed that the entire interior was covered in ice. The ship had been slowly losing heat over time due to thermal radiation. They slowly made their way into the first "forward transfer compartment", which led to the main working compartment. Before entering the working compartment, the crew sampled the air for toxic contaminants; and as a precaution before entering they put on gas masks. In the end they did a full sweep and initial assessment, and although it was in dire straits, the derelict station was deemed salvageable.

The Salyut 7 was completely without power, and the station was misaligned in such a way that the solar panels had been angled away from the sun; and thus they were incapable of providing power to the station. Aboard the Salyut the crew managed to find some operable batteries, they hooked them up to the solar array. And in another feat of brilliance they managed to use the Soyuz's thrusters to align the Salyut's solar array with the sun; effectively enabling the batteries to start charging.

The next 10 days were spent meticulously bringing up all the Salyut's vital systems one at a time in bone-chilling sub-zero temperatures with minimal systems. Starting with critical life support, followed by water, lights and communications. In these extremely arduous conditions the crew worked around the clock and managed to turn the derelict station back into a fully functional space station within such a short time, despite all odds.

Legacy

Due to the sheer brilliance and grit of the Soviets, the Salyut 7 remained in orbit for another 5 years and 8 months, until it was officially decommissioned and re-entered Earth's atmosphere on 7 February 1991. Most notably during this final period the station and its crews have managed to photograph and spectrometrically survey about 16 million km² of Earth, and conducted roughly 400 research sessions using 85 instruments.

Closing thoughts

This entire topic has been an absolute joy to research; from the sheer grit and determination, to the engineering brilliance involved. The story really unfolds like a high stakes action movie. They braved the risks, and came out on top. With that said - they actually did make a movie about this, it came out in 2017. But from what I read; the real story is far better than the dramatized movie.

I hope to come across more stories or topics like this. Although this has been widely covered, I think a lot of people that did not grow up during this period probably do not know about it. So I hope I was able to expand your horizon today!

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