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As I see it, they lost communications, and almost immediately called it a loss. This seems odd. Surely a blackout is expected due to the plasma?

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  • $\begingroup$ A factor to consider is that SpaceX believes there to be a decent chance Starship is large enough that it will be able to maintain radio contact through the entire reentry phase because the ship is so large it can essentially "punch a hole" through the atmosphere which radio waves can pass through. $\endgroup$
    – Dragongeek
    Commented Mar 18 at 8:23
  • $\begingroup$ The Space Shuttle had the same hole-punching ability, it's just that there wasn't usually a satellite in the right place to see down the hole. $\endgroup$
    – Mark
    Commented Mar 18 at 21:38
  • $\begingroup$ It was explained in the live stream, and it wasn't "immediately". $\endgroup$ Commented Mar 19 at 9:44
  • $\begingroup$ @Mark Really? I thought there were no more serious reentry blackouts for the shuttle after they got TRDS-3 up there in 1988. $\endgroup$ Commented Mar 19 at 15:09
  • $\begingroup$ @DarthPseudonym, I'm not an expert on the subject, but my understanding is that TDRS can only see down the hole if the shuttle's inclination is low enough, and I don't know if the ISS's inclination is sufficiently low. $\endgroup$
    – Mark
    Commented Mar 19 at 20:55

2 Answers 2

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This question is simply counterfactual. The call was not immediate by any stretch of the term.

On the stream from SpaceX, the video from Starship breaks up about T+48:40, and over the next 90 seconds the speed & altitude telemetry starts to drop out periodically, with the final reading at T+50:20 (25,707 km/h at 65 km).

The SpaceX hosts mention the potential for plasma interference and keep hoping for the signal to come back while they fill time by talking about the tiles and having increasingly awkward conversations about the mission that rehash things they already discussed earlier.

Right around T+55:50 (5.5 minutes since telemetry dropped out) is the first time one of the hosts even hints at the possibility of a vehicle loss on reentry -- Dan Huot said, "We're still waiting to see if we get the signal back, we're currently in a loss of signal with Starship, don't know for sure what its status is so we're continuing to listen."

For comparison, Gemini and Apollo capsules had a reentry blackout between 3 and 4 minutes, and Apollo 13's horribly long blackout (due to its shallow reentry angle) was 6 minutes total. The space shuttle didn't generally suffer from blackouts the same way, because its wide wings left a "hole" in the plasma stream that allowed the signal to get through to the TDRSS satellites. Starship's large body was expected to do something similar, so the hope was that there would be no blackout at all.

It's not until T+1:00:30 that Dan came back to announce that the telemetry on both the TDRSS (that's pronounced "teedriss", if you aren't familiar) and Starlink connections dropped at the same time, which "could mean we lost the ship" (because plasma interference would be expected to be somewhat directional and cause the connections to fuzz out at different times). That's a solid ten minutes after the loss of signal, long after the worst possible plasma effects should have ended, and it's still even a few more minutes after that before they actually officially call it a loss -- that call was made at about the time when the flight plan would have expected the ship to be dropping into the subsonic regime (the "bellyflop" position is supposed to have a terminal velocity of a little over 200 miles per hour, even without a braking burn).

Waiting over ten minutes is not "immediately" calling it a loss. They waited more than ample time for the ship to get clear of any possible interference and reestablish communications before giving up.

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They lost communications with two independent systems simultaneously, if this was due to interference you'd expect them to be lost at slightly different times as they use different transmitters, different frequencies and probably different power levels, so one would probably be at least marginally more resistant to the interference than the other.

Even with that data they didn't assume the ship had been destroyed, they made that assumption when communications still hadn't been re-established by the time they expected the ship to have splashed down in the ocean. They don't know the expected duration of the communications blackouts for starship yet (if there even is one) but they definitely shouldn't last until the ship is in the lower atmosphere.

Adding in the uncontrolled attitude of the re-entry making survival fairly unlikely in the first place, assuming the ship was lost isn't unreasonable.

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