How To Supply a Space Station
For decades unmanned spacecraft have been taking cargo to space stations to support their crews. Here I look at some of the history of such missions, and how future stations may be supplied.
When Salyut 6 launched in 1977, it had a novel feature that none of the previous five Soviet space stations possessed. On the rear end of the station it had a second docking port, which allowed other spacecraft to visit whilst a Soyuz capsule was docked. Previous stations had simply been abandoned when the supplies they had launched with ran out. Salyuts 1 and 3 had each been manned by one crew (Salyut 2 failed before a crew arrived) and Salyuts 4 and 5 had been manned by 2 crews each. Salyut 6 was able to host 6 long term crews and 10 short term visit crews. Whilst all previous Soviet space stations had operated for less than a year, Salyut 6 hosted crews for almost 4 years.
This jump in capability was due not only to the station itself, but also to the new Progress spacecraft that bought supplies. This was a variant of the Soyuz capsule that delivered crews to the space station, but with its reentry module (the middle segment of the spacecraft) replaced with a propellant tank to ref…
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