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In the ISS Expedition 56-57 Launch of Russian Soyuz MS-09, in the first view from the external camera at around 3:30, an obvious back and forth rotation (along the length axis) of the rocket can be seen against the earth background. Its amplitude diminishes until it is no longer visible around 4:30.

Is the rocket precessing? Why? And why does this precession decrease? Active correction?

Here is a video where you can see it from 3:15. I estimate fhe frequency of the phenomenon to be 0.5-0.7 Hz.

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  • $\begingroup$ I think it's called "roll"? $\endgroup$ – uhoh Jun 6 '18 at 14:44
  • $\begingroup$ @uhoh I would interpret roll more as a one-time phenomenon. Here the camera looks down along the rocket and you see it rotate back and forth (that's why I can't conclude from the video that it is precession). But I'm not a native English speaker. $\endgroup$ – Jan Doggen Jun 6 '18 at 14:59
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    $\begingroup$ @JanDoggen "roll" is generally any rotation around the longitudinal axis of a vehicle (usually considered the X axis). The video shows what would be generally considered a roll oscillation. upload.wikimedia.org/wikipedia/commons/thumb/c/c1/… It looks like an attitude correction with poor damping in the control system. $\endgroup$ – Organic Marble Jun 6 '18 at 15:14

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