Communications (As we know it) is impossible during re-entry....................
There’s the blackout, but in this case, I think the rotation doomed the Starship. If you can’t keep the heatshield pointed down, Rapid Unscheduled Disassembly is a likely outcome.
I guess there is a plasma hole behind the rocket during re entry. They were able to transmit back up to star link and then back down to earth. That is how they got comms deep into re-entry. Very slick.
Communications (As we know it) is impossible during re-entry
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Much of the reentry video was throughout an onboard Starlink. Another SpaceX first.
Except that Starship is so huge that it “punches a hole” through the plasma, leaving an opening behind it through which signals can pass. SpaceX took advantage of that in this flight by installing Starlink antennas on the upper surface of the vehicle, allowing transmission of data up, away from the Earth, to the Starlink satellite constellation and back down from them to Earth. It looked like it worked for a while, but since the ship kept rotating I suspect the antennas were eventually burned away, or the plasma reached unshielded parts of it causing sudden destruction.