4 ms·

Can someone spell out the consequences of a failed thruster? Eg miss the reentry cone and skip off the atmosphere into space?

lupusreal 2y ago
Or come in too steep and burn up. Or miss the target drop zone and possibly come down in the wilderness or ocean (it's meant to land on flat and level land.)
khuey 2y ago
My understanding (which may be wrong) is that they don't really understand how it's failed at this point so it could be anything from "no thrust" to "explodes and sends debris into the ISS".
bell-cot 2y ago
That's one possibility. Unfortunately, failure modes are not limited to "the thruster(s) shut down before the desired burn was completed". Worse case looks kinda like this, but in space: https://www.cbsnews.com/news/spacex-explosion-destroyed-crew-dragon-spacecraft-blamed-on-leaking-valve/ https://www.cbsnews.com/news/spacex-explosion-destroyed-crew...
pavel_lishin 2y ago
> miss the reentry cone and skip off the atmosphere into space? My layman understanding is that this was never an option even for the Apollo trips from the moon - the problem was that a wrong re-entry angle wouldn't slow the capsule down enough to bring it down to the surface, and it would have to orbit several more times before finally slowing down enough to return. This was a problem for two reasons: (1) the landing site would be unpredictable, and it wouldn't really do to land on the Kremlin, or in the middle of the Sahara, or in the middle of the Pacific. (2) The capsules didn't have enough supplies to keep the astronauts alive for too long, and too many orbits would mean that they'd be dead on arrival.
- kfarr 2y ago
  Incorrect angle also leads to higher temperatures that may exceed design capabilities during re-entry
- deeth_starr_v 2y ago
  In Carrying the Fire, in pre Apollo days when they did manual burns for re-entry, this was described as a big worry (burn sending you off into space). But maybe that was mitigated
JumpCrisscross 2y ago
> Can someone spell out the consequences of a failed thruster? Eg miss the reentry cone and skip off the atmosphere into space? With no thrusters Starliner can’t orient itself during reëntry, which almost guarantees burning up. I’m not sure what the minimum number of thrusters Starliner needs to safely deörbit.
- carabiner 2y ago
  > deörbit Do you have this set as autocorrect or do you type the ö each time?
  - riffic 2y ago
    isn't this a "new yorker styleguide" sort of idiosyncrasy? EDIT: "Languages such as Dutch, Afrikaans, Catalan, French, Galician, and Spanish make regular use of the diaeresis" according to wikipedia.
    - lainga 2y ago
      Only for repeated vowels, which deoörbit is not
      - CoastalCoder 2y ago
        Excessive diaeresis is usually caused by a vowel problem.
        dmvdoug 2y ago
        Explosive diaeresis is the woooorst.
      - plesner 2y ago
        It's a diphthong though. Same as the difference between George (roughly dzo:rdz) and Geörge (roughly dze:ordz).
  - 2y ago
sandworm101 2y ago
There are several issues. One is that the craft doesn't properly separate from the station. If it backs away from the station, then dies, it will risk colliding with the ISS after an orbit. (Lower perigee but same apogee = collision potential.) The craft needs to back away from the station sufficiently to reenter or at least conduct a second maneuver to ensure its apogee is lower than the ISS's orbit.

lupusreal 2y ago

Or come in too steep and burn up. Or miss the target drop zone and possibly come down in the wilderness or ocean (it's meant to land on flat and level land.)

khuey 2y ago

My understanding (which may be wrong) is that they don't really understand how it's failed at this point so it could be anything from "no thrust" to "explodes and sends debris into the ISS".

bell-cot 2y ago

That's one possibility. Unfortunately, failure modes are not limited to "the thruster(s) shut down before the desired burn was completed". Worse case looks kinda like this, but in space: https://www.cbsnews.com/news/spacex-explosion-destroyed-crew-dragon-spacecraft-blamed-on-leaking-valve/ https://www.cbsnews.com/news/spacex-explosion-destroyed-crew...

pavel_lishin 2y ago

> miss the reentry cone and skip off the atmosphere into space? My layman understanding is that this was never an option even for the Apollo trips from the moon - the problem was that a wrong re-entry angle wouldn't slow the capsule down enough to bring it down to the surface, and it would have to orbit several more times before finally slowing down enough to return. This was a problem for two reasons: (1) the landing site would be unpredictable, and it wouldn't really do to land on the Kremlin, or in the middle of the Sahara, or in the middle of the Pacific. (2) The capsules didn't have enough supplies to keep the astronauts alive for too long, and too many orbits would mean that they'd be dead on arrival.

kfarr 2y ago
Incorrect angle also leads to higher temperatures that may exceed design capabilities during re-entry
deeth_starr_v 2y ago
In Carrying the Fire, in pre Apollo days when they did manual burns for re-entry, this was described as a big worry (burn sending you off into space). But maybe that was mitigated

JumpCrisscross 2y ago

> Can someone spell out the consequences of a failed thruster? Eg miss the reentry cone and skip off the atmosphere into space? With no thrusters Starliner can’t orient itself during reëntry, which almost guarantees burning up. I’m not sure what the minimum number of thrusters Starliner needs to safely deörbit.

carabiner 2y ago
> deörbit Do you have this set as autocorrect or do you type the ö each time?
- riffic 2y ago
  isn't this a "new yorker styleguide" sort of idiosyncrasy? EDIT: "Languages such as Dutch, Afrikaans, Catalan, French, Galician, and Spanish make regular use of the diaeresis" according to wikipedia.
  - lainga 2y ago
    Only for repeated vowels, which deoörbit is not
    - CoastalCoder 2y ago
      Excessive diaeresis is usually caused by a vowel problem.
      - dmvdoug 2y ago
        Explosive diaeresis is the woooorst.
    - plesner 2y ago
      It's a diphthong though. Same as the difference between George (roughly dzo:rdz) and Geörge (roughly dze:ordz).
- 2y ago

sandworm101 2y ago

There are several issues. One is that the craft doesn't properly separate from the station. If it backs away from the station, then dies, it will risk colliding with the ISS after an orbit. (Lower perigee but same apogee = collision potential.) The craft needs to back away from the station sufficiently to reenter or at least conduct a second maneuver to ensure its apogee is lower than the ISS's orbit.