I watched the livestream of the launch of the SpaceX SARah-1 Mission.

Shortly after the boostback burn there is this squiggly white line that moves away from the first stage, starting at T+03:54. It happens a couple of times during this section of the flight, always from the same spot and angle relative to the stage, even after rotating a lot. A screenshot with obligatory red arrow:

image of the first stage with the squiggly white line

What is this? A couple of possibilities I see:

  • some debris coming loose
  • excess fluid being dumped
  • camera glare (unlikely because of the angle change)
  • 1
    $\begingroup$ The one at 4:14 is more startling - it "reverses direction" at 4:15 compared to the background & rocket when the thruster fires. Presumably what we see is the whole rocket body translating towards it without much rotation, e.g. a thrusters fired at both ends. Surprises me since I expected the thrusters to be providing rotation to orient the body. $\endgroup$ Jun 18, 2022 at 16:23

1 Answer 1


As is so often the case, this is almost certainly ice. There's a vent or umbilical coupling on that side: you can see a few points in the flight where there's fog streaming back from that part of the vehicle, from venting gases, or perhaps boil-off of residual propellant as ambient pressure dropped. And the foggy launch conditions showed there was plenty of water in the air.


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