/sci/ - Science & Math

>Mysterious spiral of light spotted in North caused by SpaceX rocket, physicist says
>"Very often when they're finished with their mission, they will actually sort of eject some of their propellant. And when that goes out in space and the sun is shining on it, you can see that in the sky if you're [in the] dark on the ground," Hampton said.
https://www.msn.com/en-ca/news/other/mysterious-spiral-of-light-spotted-in-north-caused-by-spacex-rocket-physicist-says/ar-AA19YPnk

Is this explanation legit? Why are they venting leftover propellant instead of relighting the Merlin vacuum engine for a deorbit burn?