On recent launch I noticed, that some white things jumping on vacuum engine in space. Something like garbage or condensate. See video at right at times when Earth is at left:

What is it?

enter image description here

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    $\begingroup$ Seems like ice, which might have formed on LO2 ducts and dropped (under acceleration) into the crook of a pipe. You can see some of it sliding around at 20:18 $\endgroup$
    – SF.
    Commented Oct 8, 2020 at 9:30
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    $\begingroup$ I remember that John Insprucker (SpaceX employee and the voice of many falcon-9 launch videos) confirmed it. But I can't find the video. It's oxygen ice. When liquid oxygen leaves the valve in vacuum, the hottest molecules evaporate and take the thermal energy, so the remining oxygen freezes. Of course, there should not be direct sunlight, too. $\endgroup$
    – Heopps
    Commented Oct 8, 2020 at 9:41
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    $\begingroup$ There are a couple other questions on the site about things on Merlin engines where the answer is "solid oxygen". Here's one space.stackexchange.com/q/25616/6944 I don't know if this would be considered a duplicate since the deposit may not be on exactly the same part of the engine.... Another space.stackexchange.com/q/15152/6944 $\endgroup$ Commented Oct 8, 2020 at 12:43