First non-cooperative docking between two spacecraft

The first docking of a spacecraft with what is known as a "non-cooperative object" took place on 8 June 1985. The crew of Soyuz T-13 – Vladimir Dzhanibekov and Viktor Savinykh (all RUS) – successfully docked their ship with the crippled Salyut-7 space station, which was spinning uncrewed and out of control in Low-Earth Orbit, having lost electrical power earlier that year. Docking between two spacecraft usually requires both to be under active attitude control, keeping them aligned with each other.

Soyuz T-13 was a daring and high-risk operation. When the station's electrical systems went down, Salyut-7 lost attitude control, leaving it slowly tumbling through space. No-one had ever attempted to dock with a spacecraft that wasn't being actively maintained in a stable orientation before.

The pilot chosen for this mission, Vladimir Dzhanibekov, was a veteran cosmonaut who had flown four missions in the Soyuz since 1978, including one in which he had to manually dock with Salyut-7 after his Soyuz suffered a guidance failure. He was partnered with engineer Viktor Savinykh, whose expertise would be useful in restoring power to the crippled station. Their Soyuz was customized for the unusual mission; its automatic docking systems were removed, as was one of its seats. In place Dzhanibekov and Savinykh had extra food and water, a set of laser rangefinders, night-vision goggles and as much fuel as the spacecraft could carry.

Soyuz T-13 lifted off on 6 June 1985, and took two days to reach Salyut-7. The two-man crew made the final approach while keeping the station in view of one of the Soyuz's windows, occasionally taking readings with a hand-held laser rangefinder. Despite the worries of many on the ground, Dzhanibekov was able to complete the docking manoeuvre on his first attempt, expertly matching the roll of the off-kilter station to bring the Soyuz around to its forward port.

This historic achievement was just the beginning of an extremely difficult mission, however. They first had to gingerly open the vents between their ship and the interior of the station, listening carefully for the hiss that would tell them the station had depressurized. Once inside, they found the station dark, silent and freezing cold. As a test, Dzhanibekov – clad in a thick winter coat – spat on an internal panel and watched it freeze solid in three seconds.

With the station's water tanks frozen, they had just 12 days to save the station. Longer than that, and the supplies they brought with them would run out, forcing them to return to Earth. Long cables were strung through the cabin of the dark station, connecting the batteries directly to the solar panels. The Soyuz's engines were then used to turn the station to face the sun. With this jump-start, the crew were able to start bringing systems back online. By the end of their first 12 days on the station, they'd successfully restored the station to working condition.

In recent years, space agencies have become very interested in non-cooperative docking. There are hundreds of large dead satellites in orbit above Earth, and as our skies become more congested, the likelihood of a catastrophic collision only increases. Non-cooperative docking would allow for dead satellites to be captured and either deorbited or repurposed.