I was wondering. I just watched the Starlink launch from 12/17/2022 (Starlink Group 4-37).

At about +3:53 into the launch, on the first stage re-entry, there was a weird anomaly, which kinda looked like an "electronic" bird. I was hoping someone could look at the footage and identify what I saw.

It's on the first stage re-entry, right by the grid flap on the left. moves like a bird, from under the grid flap and moves up and eventually out of the frame to the left. enter image description here

enter image description here


1 Answer 1


Here is an clip of the event:

Debris falling off F9

This is probably a vaguely crescent-shaped chunk of ice that's fallen off the rocket. It spins, and either due to atmospheric drag or being pushed by one of the first-stage attitude control thrusters, appears to spin faster by the time it exits the frame.

The Falcon 9 uses liquid oxygen and kerosene as propellants and due to the cryogenic temperatures of the oxidizer, atmospheric water vapor condensates on and freezes on the exterior of the Falcon 9 rocket while it is sitting on the launch pad.

When the rocket takes off, the vibrations, drag from the atmosphere, and general heating up of the system make these large chunks of ice fall off. Typically, you can see chunks falling past the rocket right after takeoff, but small bits of ice falling past the rocket can be seen even when the rocket is already rather high up.

  • $\begingroup$ It might even be possible that it's nitrogen. I think the pressure and temperature would be low enough for it to freeze. $\endgroup$ Dec 18, 2022 at 12:54
  • $\begingroup$ Even nitrogen and oxygen freeze in vacuum (some part of). There is no atmosphere for thermal exchange, so the hottest molecules just evaporate and take the heat, and the remaining molecules are much cooler so they condense in solid. $\endgroup$
    – Heopps
    Dec 20, 2022 at 6:39

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.