When spasecraft accelerates its center of masses should be on the line of force vector otherwise it will start to spin. How does ISS hold its orientation when accelerating? Do gyros hold station orientation?

  • $\begingroup$ When thrust is used to raise an orbit, it slows down. So "accelerates" could be slightly wrong, depending on if it is meant to mean some change in velocity vector, or "speeds up." But I'm nitpicking :) $\endgroup$
    – uhoh
    Commented Mar 3, 2017 at 14:02

1 Answer 1


Yes. The ISS has quite large control moment gyroscopes.


The Russian section also has RCS thrusters for desaturating the gyroscopes, and the boosting vehicles have their own RCS thrusters and momentum control systems.

  • 4
    $\begingroup$ ISS uses Control Moment Gyroscopes (CMGs), not reaction wheels. Reaction wheels have their axis fixed to the vehicle body and impart angular momentum by spinning up or down. CMGs are attached to the vehicle via a set of gimbals and run at a constant speed, providing an inertially stable platform. Attitude control is then effected by applying torque to the gimbal joints, not the rotor. $\endgroup$
    – Tristan
    Commented Mar 3, 2017 at 16:15

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