4 ms·

They turned off the engines early specifically to not reach orbital velocity.

by tekla 2y ago

pclmulqdq 2y ago
There was an in-orbit relight in the IFT3 flight plan, which failed to happen. IFT4 is somewhat more conservative - just get to orbit (happened), pseudo-land the booster (happened), and get back out of orbit (remains to be seen). The amount of disinformation that SpaceX and Musk create around failed tests is really annoying and honestly somewhat problematic. It would be nice if SpaceX could just honestly say "this worked and this didn't," but we have to pretend that everything is a miraculous success. After the engine failed on IFT3, the immediate line was "we planned it this way" and then days later "we reached orbital velocity." Launching rockets is impressive enough that you don't have to try to gaslight us all on the way there. As far as I can tell, my scorecard has IFT1 and IFT3 as failures based on what the flight plans said going in, and IFT2 and (so far) IFT4 as successes. Edit: I'm suspicious of the fact that they turned off the feed right after cutting the engines and some gas vented. Previous tests have had no problem showing a video feed at this phase.
- tekla 2y ago
  I'm always amazed at how wrong people on HN are. The orbital relight test was not a factor in the fact that Starship was not intended to reach orbital velocity. You may have noticed that the flight plan indicated that Starship was to land somewhere in the Indian ocean and usually reaching orbital velocity vastly increases the difficulty of doing a planned reentry. The flight plans had them turning off the engines before they actually reached orbital velocity They scrapped the relight test when they realized that they were losing control authority. The relight test was not meant for reaching orbit, it was to prove they COULD relight the engines on Starship while in space. Just stop being wrong.
  - pclmulqdq 2y ago
    The original IFT-3 flight plan had them reaching orbit and then doing the in-orbit relight as a de-orbit burn. At that altitude, there's enough drag that you will de-orbit pretty quickly if you are in orbit and your de-orbit burn fails, so there was no risk of a big piece of space junk. The disinformation I mentioned is why everyone keeps being "wrong" about SpaceX. It's incredibly difficult to be right. Here's the original graphic that SpaceX put out before the flight happened: https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiVxFzY9rdOu6cXly46axk8Wq2LH3tMqWEZOij9f3s2YjsWDPAycrsfQE1SgZ3f25OD7XOBIw_1WTRyKyZGUbLWHHLP9P0HSrGcB1kyEp8MGtWScjVbb_BkYOw_y_zNNZ2RvRYoljAL4693YPmQUOMPMzUoLYimNtqIkEAm6dBIoCGcnIRfNruobriImqoi/s2048/SpaceX%20Starship%20B10S28%20orbital%20flight%20test%203%20infographic%20by%20Tony%20Bela.jpg https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi...
    - mpweiher 2y ago
      No. All the info about IFT-3 pre launch always mentioned that they were deliberately not actually going to enter orbit, so as not to need an unproven de-orbit burn to avoid 100t of space junk. 100t of space junk that would then re-enter at some unpredictable time. Bad idea. So they were on a trajectory that would automatically have the vehicle re-enter the atmosphere and splash down in some ocean, even if it were fully inert.
      - pclmulqdq 2y ago
        A 150 km orbit has enough drag to de-orbit you very quickly if you don't propulsively stay in it. The atmosphere doesn't just suddenly stop at 100 km, it gets exponentially thinner and thinner, and at 150 km there's still plenty of atmosphere to slow down a big chunk of stainless steel. Even 3x higher there's enough atmosphere that tiny satellites can essentially turn their solar panels into sails and deorbit with no propulsion within a few weeks. The ISS at ~400 km has to regularly burn their engines to stay in orbit. Read the IFT-3 pre-flight materials, preferably from a source that comes from before the flight. They clearly intended to enter an orbital trajectory and then get out of it. SpaceX's historical revisionism muddies the waters. At the very least, they would not have announced (ie lied about) successful orbital insertion (which they didn't do) if they had no intention to get there.
        enslavedrobot 2y ago
        You do not rely on drag to deorbit a stainless steel 10 story building partially covered in heat shielding in a random location. They deliberately selected a suborbital trajectory with a velocity that matched orbital reentry... See 1:20 of this video. Everyone who actually follows SpaceX knows this. You are confidently and totally wrong.https://youtu.be/LOerY66mrPc?si=5FUAARFQ3Z98eqjb https://youtu.be/LOerY66mrPc?si=5FUAARFQ3Z98eqjb
        pclmulqdq 2y ago
        All I see is a video from after IFT-3 that parrots SpaceX's post-hoc rationalization about the fact that their craft could not reach orbital velocity. If you look at the GAO report on Artemis, one of the big issues they mentioned is that Starship has not proven that it can reach orbit, and SpaceX is very interested in making sure that the narrative is that it can and did. It was only after the fact that they said that the never intended to reach an orbital trajectory with IFT-3. And actually, people rely on drag to deorbit huge objects in space in a controlled manner all the time. It's the preferred way to do it, and is basically the only way it's done - any satellite with fuel left will just stay in orbit. They have it down to a science. Usually they aim for the middle of an ocean. Sometimes they miss and chunks fall in a backyard.

They turned off the engines early specifically to not reach orbital velocity.

by tekla 2y ago

They turned off the engines early specifically to not reach orbital velocity.

There was an in-orbit relight in the IFT3 flight plan, which failed to happen. IFT4 is somewhat more conservative - just get to orbit (happened), pseudo-land the booster (happened), and get back out of orbit (remains to be seen). The amount of disinformation that SpaceX and Musk create around failed tests is really annoying and honestly somewhat problematic. It would be nice if SpaceX could just honestly say "this worked and this didn't," but we have to pretend that everything is a miraculous success. After the engine failed on IFT3, the immediate line was "we planned it this way" and then days later "we reached orbital velocity." Launching rockets is impressive enough that you don't have to try to gaslight us all on the way there. As far as I can tell, my scorecard has IFT1 and IFT3 as failures based on what the flight plans said going in, and IFT2 and (so far) IFT4 as successes. Edit: I'm suspicious of the fact that they turned off the feed right after cutting the engines and some gas vented. Previous tests have had no problem showing a video feed at this phase.

tekla 2y ago
I'm always amazed at how wrong people on HN are. The orbital relight test was not a factor in the fact that Starship was not intended to reach orbital velocity. You may have noticed that the flight plan indicated that Starship was to land somewhere in the Indian ocean and usually reaching orbital velocity vastly increases the difficulty of doing a planned reentry. The flight plans had them turning off the engines before they actually reached orbital velocity They scrapped the relight test when they realized that they were losing control authority. The relight test was not meant for reaching orbit, it was to prove they COULD relight the engines on Starship while in space. Just stop being wrong.
- pclmulqdq 2y ago
  The original IFT-3 flight plan had them reaching orbit and then doing the in-orbit relight as a de-orbit burn. At that altitude, there's enough drag that you will de-orbit pretty quickly if you are in orbit and your de-orbit burn fails, so there was no risk of a big piece of space junk. The disinformation I mentioned is why everyone keeps being "wrong" about SpaceX. It's incredibly difficult to be right. Here's the original graphic that SpaceX put out before the flight happened: https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiVxFzY9rdOu6cXly46axk8Wq2LH3tMqWEZOij9f3s2YjsWDPAycrsfQE1SgZ3f25OD7XOBIw_1WTRyKyZGUbLWHHLP9P0HSrGcB1kyEp8MGtWScjVbb_BkYOw_y_zNNZ2RvRYoljAL4693YPmQUOMPMzUoLYimNtqIkEAm6dBIoCGcnIRfNruobriImqoi/s2048/SpaceX%20Starship%20B10S28%20orbital%20flight%20test%203%20infographic%20by%20Tony%20Bela.jpg https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi...
  - mpweiher 2y ago
    No. All the info about IFT-3 pre launch always mentioned that they were deliberately not actually going to enter orbit, so as not to need an unproven de-orbit burn to avoid 100t of space junk. 100t of space junk that would then re-enter at some unpredictable time. Bad idea. So they were on a trajectory that would automatically have the vehicle re-enter the atmosphere and splash down in some ocean, even if it were fully inert.
    - pclmulqdq 2y ago
      A 150 km orbit has enough drag to de-orbit you very quickly if you don't propulsively stay in it. The atmosphere doesn't just suddenly stop at 100 km, it gets exponentially thinner and thinner, and at 150 km there's still plenty of atmosphere to slow down a big chunk of stainless steel. Even 3x higher there's enough atmosphere that tiny satellites can essentially turn their solar panels into sails and deorbit with no propulsion within a few weeks. The ISS at ~400 km has to regularly burn their engines to stay in orbit. Read the IFT-3 pre-flight materials, preferably from a source that comes from before the flight. They clearly intended to enter an orbital trajectory and then get out of it. SpaceX's historical revisionism muddies the waters. At the very least, they would not have announced (ie lied about) successful orbital insertion (which they didn't do) if they had no intention to get there.
      - enslavedrobot 2y ago
        You do not rely on drag to deorbit a stainless steel 10 story building partially covered in heat shielding in a random location. They deliberately selected a suborbital trajectory with a velocity that matched orbital reentry... See 1:20 of this video. Everyone who actually follows SpaceX knows this. You are confidently and totally wrong.https://youtu.be/LOerY66mrPc?si=5FUAARFQ3Z98eqjb https://youtu.be/LOerY66mrPc?si=5FUAARFQ3Z98eqjb
        pclmulqdq 2y ago
        All I see is a video from after IFT-3 that parrots SpaceX's post-hoc rationalization about the fact that their craft could not reach orbital velocity. If you look at the GAO report on Artemis, one of the big issues they mentioned is that Starship has not proven that it can reach orbit, and SpaceX is very interested in making sure that the narrative is that it can and did. It was only after the fact that they said that the never intended to reach an orbital trajectory with IFT-3. And actually, people rely on drag to deorbit huge objects in space in a controlled manner all the time. It's the preferred way to do it, and is basically the only way it's done - any satellite with fuel left will just stay in orbit. They have it down to a science. Usually they aim for the middle of an ocean. Sometimes they miss and chunks fall in a backyard.