Given a cylindrically-shaped space station rotating at 1-2 rpm (Stanford Torus, as an example) what are the engineering considerations regarding docking? The central hub would be the logical docking location, but that would be rotating as well. Is there a way to have the actual docking location not rotate? The problem then would be how to transfer to the rotating spokes for transit out to the 1g habitat section of the station. A related question - if you needed a zero-g environment for space manufacturing (crystals, etc.) how would that be connected to the rotating station? I suppose the manufacturing facility could be built out from the central hub on the side opposite from the docking location. That still returns to the question of how to transfer from a non-rotating location to the rotational portions of the station.


2 Answers 2


1-2 RPM is not much - a craft rotating at such a speed would not be very hard to control, so the whole problem could be deferred to docking software/procedure, only requiring the docking port be aligned with the craft's center of mass.

If that's not an option, say, the docking craft's rotation axis can't go through the docking port, a smart approach would have a two-phase docking mechanism: a rotating mechanical docking system placed on extending platform or robotic arm, with active motor that counter-rotates the station's port relative to the station so that it's rotation relative to the craft is zero. After docking to it, creating a firm mechanical connection between the craft and the station, the port's motors are de-spun, the craft enters the same rotation as the station (around the common center of mass, not necessarily in line with either of the ports), but is firmly attached to the port, and then it's guided using the port's mechanics to the "second stage docking", actual classic docking port allowing crew and cargo transfer.

Spinning airlocks are currently a stuff of sci-fi novels. If you need a station with non-spinning part and a spinning part, you build two stations.

  • $\begingroup$ "the whole problem could be deferred to docking software/procedure" That reminds me of the docking scene in 2001. $\endgroup$
    – user
    Feb 20, 2017 at 12:47
  • $\begingroup$ @MichaelKjörling: Certainly not Interstellar level of difficulty. :) $\endgroup$
    – SF.
    Feb 20, 2017 at 12:53
  • $\begingroup$ Hey, it was tough in the original Elite. $\endgroup$
    – Steve
    Feb 22, 2017 at 16:38
  • $\begingroup$ @Steve: Dunno about Elite, but it was tough in Frontier WITHOUT AUTOPILOT. With autopilot it was trivial. $\endgroup$
    – SF.
    Feb 22, 2017 at 16:43

Mayby possibly answer is: to catch a docking spaceship using long robotic arm, and, by manipulating of them, changing motion vectors of space ship gradually (by a lot of motors of the arm), and simply to pull down in lock in a Torus.

This is my crazy idea for docking to rotating space station without docking port in axis of Torus.

  • $\begingroup$ Do you suggest docking to the central axis of the torus or to the torus itself? Docking to the torus itself would cause a rotating imbalance and disturb the artifical gravity of space station. A rotating space station should have no static or dynamic unbalance, not before docking and not after docking. To sustain balance, two identical space ship should dock in the same time at opposite points of the torus. $\endgroup$
    – Uwe
    Jan 23, 2018 at 16:02
  • $\begingroup$ Yes. I thing about docking to torus directly. Maybe are existing some other metods to compensate these disturbances? (jets? symetrical arm ?) Or disturbance will not be too big, for huge mass of big space station? $\endgroup$ Jan 23, 2018 at 16:57
  • $\begingroup$ If the ratio between the mass of the space station and the space ship is so big that an astronaut would not feel any periodic variation of the artifical gravity, docking to the torus directly may be accepted. $\endgroup$
    – Uwe
    Jan 23, 2018 at 17:30

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.