4 ms·

Seems like the booster landing burn did not light all the engines and so it crashed into the water.

wat10000 3mo ago
The “chopstick” catcher arrangement seems awfully fragile. Would the ground equipment have survived this if it had been a real catch?
- pixl97 3mo ago
  Yes, because it would have landed a few hundred meters out from the chopsticks. It swings in towards the catcher as part of its slowdown. If it doesn't slow down, that doesn't happen.
- tenuousemphasis 3mo ago
  They generally initiate landing aiming just off shore and only adjust to the landing pad after everything is nominal. So yes.
- consensus1 3mo ago
  Rockets have a self destruct feature to avoid exactly this type of contingency
  - inglor_cz 3mo ago
    By the time that the booster returns to the landing zone, the Flight Termination System (FTS) is AFAIK no longer active and cannot be reactivated. Which makes sense because it is a bunch of high explosives, now nearing some valuable equipment. The SpaceX solution is to steer carefully and have the default trajectory end in the sea. Only if everything looks good, is the booster redirected to the tower.
    - wat10000 3mo ago
      I wonder what happens when things go wrong after everything looks good. They punched a good number of holes in their landing barges when they were perfecting Falcon 9 landings. And I imagine this crazy catch tower is a lot more expensive than a barge with a flat surface.
      - inglor_cz 3mo ago
        Falcon 9 engines (Merlins) cannot throttle down, they either run on max power or they don't. Which means that any attempts to land are incredibly risky. You have to reignite them at the precise moment to slow down the rocket to zero at the height of the landing platform, or else. That is why the maneuver is called "suicide burn", and it is incredible that someone actually perfected something as crazy as this. The landing legs can absorb a tiny error, but anything over that = Rapid Unscheduled Disassembly (Monty Python theme starts to play in the background...) Raptors are much more finely controllable and both stages of Starship can even hover when necessary, so the total control envelope, while not perfect, is much larger. That is why they can even try to land into a steely embrace, with no landing legs used.
        wat10000 3mo ago
        Merlin and Raptor can both throttle to about 40%. The difference is that Super Heavy has way more engines, so 40% of one engine is a lot less thrust relative to the mass of the nearly empty booster. Did the suicide burn actually play a role in the various barge-holing events? It’s been a while but I don’t remember that being the hard part.
        inglor_cz 3mo ago
        I was mistaken, Merlins can indeed throttle down. Thanks for correction. What they cannot is achieve thrust-to-weight ratio of <= 1 when the first stage is empty, so controlled descent is basically impossible and suicide burn is the only option to land. When it comes to failed returns, I think that at least once they ran out of fuel several meters early(?)
stephc_int13 3mo ago
It was going in the water anyway, but yeah, it touched visibly faster than it should have.
ButlerianJihad 3mo ago
The actual objective was to crash very slowly into the water, and to that end, I believe they planned for about 13 out of 33 to light for the "landing burn". But only about 5 lit up at that time, giving them a higher-speed crash-landing. However, the landing site was exactly where they needed to be, and done in complete safety, so that is good. They had been explaining the post-ignition abort from last week, and showed how 4 out of 33 engines had failed to light on the first stage. This was due to some kind of pump malfunctions. They said that if 1 or 2 fail, it's OK to launch, but more than 2 is an automatic abort. So they were able to replace the finicky motors and fully test them out. Who knows what caused the underthrust for the landing burn, but at least all 33 engines were operational at launch, and they got plenty of data from this test run, and all Starlink v3 satellites have been deployed successfully for their "suborbital speedrun", so this test flight is doing really awesome!
- ls612 3mo ago
  Damn so this probably means another identical suborbital flight in 6-8 weeks. It is looking less and less likely that we will see either prop transfer or a ship catch this year.
  - NetMageSCW 3mo ago
    They don’t have to catch the booster to test any of that.
  - davmar 3mo ago
    i don't think so - the ascent looked good. i don't think they need to put the ship on another suborbital trajectory because the booster landing burn failed. also, i don't think this impacts prop transfer or ship catch - both are separate problems.
    - ls612 3mo ago
      I think this is technically true but that they want a seamless suborbital flight (like the last two for the Block 2) before they move forward on those other goals.
deleted 3mo ago
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ChuckMcM 3mo ago
Yup. Some of the Youtubers (like NASA Spaceflight) had video of it hitting the water pretty fast and hard. That said, this is the only test failure so far. I'm cautiously hopeful they get Ship to touch down. (it will explode after it does because of physics but stepping lightly onto the ocean will be a win)
- cucumber3732842 3mo ago
  >it will explode after it does because of physics Is this just a fancy way of saying lightweight fragile aerospace tube with hot stuff all over the outside and flammable stuff on the inside will not respond well to falling on it's side or is there some other thing going on here I don't know about.
  - ACCount37 3mo ago
    No, that's exactly what happens. Most of the time. There was a couple of times when SpaceX accidentally soft landed a Falcon 9 first stage into the ocean, and had it just float around. They're yet to do that trick with Starship though. EDIT: Of fucking course.
  - ChuckMcM 3mo ago
    Sort of? Everything is weight. And since it isn't a design feature to lay down in water there isn't any weight budget for making that modality survivable? So typically when it falls (and this thing is really tall) the interior tanks detach from their mounts and hit the inside walls and rupture. The skin is still hot, oxygen and remaining fuel mix and it goes boom. This time we had fires but no boom. I look forward to hearing what was different.
    - m4rtink 3mo ago
      Starship is quite a bit sturdier thanks to the stainless steel used & very efficient engines that make it possible to have the structure heavier. We had it demonstrated in the past with Starship surviving multiple burnthroughts and now in failing to explode. :-)
  - deleted 3mo ago
fastball 3mo ago
Re-light seems to be one of their biggest remaining obstacles in a lot of these flight tests.

The “chopstick” catcher arrangement seems awfully fragile. Would the ground equipment have survived this if it had been a real catch?

pixl97 3mo ago
Yes, because it would have landed a few hundred meters out from the chopsticks. It swings in towards the catcher as part of its slowdown. If it doesn't slow down, that doesn't happen.
tenuousemphasis 3mo ago
They generally initiate landing aiming just off shore and only adjust to the landing pad after everything is nominal. So yes.
consensus1 3mo ago
Rockets have a self destruct feature to avoid exactly this type of contingency
- inglor_cz 3mo ago
  By the time that the booster returns to the landing zone, the Flight Termination System (FTS) is AFAIK no longer active and cannot be reactivated. Which makes sense because it is a bunch of high explosives, now nearing some valuable equipment. The SpaceX solution is to steer carefully and have the default trajectory end in the sea. Only if everything looks good, is the booster redirected to the tower.
  - wat10000 3mo ago
    I wonder what happens when things go wrong after everything looks good. They punched a good number of holes in their landing barges when they were perfecting Falcon 9 landings. And I imagine this crazy catch tower is a lot more expensive than a barge with a flat surface.
    - inglor_cz 3mo ago
      Falcon 9 engines (Merlins) cannot throttle down, they either run on max power or they don't. Which means that any attempts to land are incredibly risky. You have to reignite them at the precise moment to slow down the rocket to zero at the height of the landing platform, or else. That is why the maneuver is called "suicide burn", and it is incredible that someone actually perfected something as crazy as this. The landing legs can absorb a tiny error, but anything over that = Rapid Unscheduled Disassembly (Monty Python theme starts to play in the background...) Raptors are much more finely controllable and both stages of Starship can even hover when necessary, so the total control envelope, while not perfect, is much larger. That is why they can even try to land into a steely embrace, with no landing legs used.
      - wat10000 3mo ago
        Merlin and Raptor can both throttle to about 40%. The difference is that Super Heavy has way more engines, so 40% of one engine is a lot less thrust relative to the mass of the nearly empty booster. Did the suicide burn actually play a role in the various barge-holing events? It’s been a while but I don’t remember that being the hard part.
        inglor_cz 3mo ago
        I was mistaken, Merlins can indeed throttle down. Thanks for correction. What they cannot is achieve thrust-to-weight ratio of <= 1 when the first stage is empty, so controlled descent is basically impossible and suicide burn is the only option to land. When it comes to failed returns, I think that at least once they ran out of fuel several meters early(?)

stephc_int13 3mo ago

It was going in the water anyway, but yeah, it touched visibly faster than it should have.

ButlerianJihad 3mo ago

The actual objective was to crash very slowly into the water, and to that end, I believe they planned for about 13 out of 33 to light for the "landing burn". But only about 5 lit up at that time, giving them a higher-speed crash-landing. However, the landing site was exactly where they needed to be, and done in complete safety, so that is good. They had been explaining the post-ignition abort from last week, and showed how 4 out of 33 engines had failed to light on the first stage. This was due to some kind of pump malfunctions. They said that if 1 or 2 fail, it's OK to launch, but more than 2 is an automatic abort. So they were able to replace the finicky motors and fully test them out. Who knows what caused the underthrust for the landing burn, but at least all 33 engines were operational at launch, and they got plenty of data from this test run, and all Starlink v3 satellites have been deployed successfully for their "suborbital speedrun", so this test flight is doing really awesome!

ls612 3mo ago
Damn so this probably means another identical suborbital flight in 6-8 weeks. It is looking less and less likely that we will see either prop transfer or a ship catch this year.
- NetMageSCW 3mo ago
  They don’t have to catch the booster to test any of that.
- davmar 3mo ago
  i don't think so - the ascent looked good. i don't think they need to put the ship on another suborbital trajectory because the booster landing burn failed. also, i don't think this impacts prop transfer or ship catch - both are separate problems.
  - ls612 3mo ago
    I think this is technically true but that they want a seamless suborbital flight (like the last two for the Block 2) before they move forward on those other goals.

deleted 3mo ago

[deleted]

ChuckMcM 3mo ago

Yup. Some of the Youtubers (like NASA Spaceflight) had video of it hitting the water pretty fast and hard. That said, this is the only test failure so far. I'm cautiously hopeful they get Ship to touch down. (it will explode after it does because of physics but stepping lightly onto the ocean will be a win)

cucumber3732842 3mo ago
>it will explode after it does because of physics Is this just a fancy way of saying lightweight fragile aerospace tube with hot stuff all over the outside and flammable stuff on the inside will not respond well to falling on it's side or is there some other thing going on here I don't know about.
- ACCount37 3mo ago
  No, that's exactly what happens. Most of the time. There was a couple of times when SpaceX accidentally soft landed a Falcon 9 first stage into the ocean, and had it just float around. They're yet to do that trick with Starship though. EDIT: Of fucking course.
- ChuckMcM 3mo ago
  Sort of? Everything is weight. And since it isn't a design feature to lay down in water there isn't any weight budget for making that modality survivable? So typically when it falls (and this thing is really tall) the interior tanks detach from their mounts and hit the inside walls and rupture. The skin is still hot, oxygen and remaining fuel mix and it goes boom. This time we had fires but no boom. I look forward to hearing what was different.
  - m4rtink 3mo ago
    Starship is quite a bit sturdier thanks to the stainless steel used & very efficient engines that make it possible to have the structure heavier. We had it demonstrated in the past with Starship surviving multiple burnthroughts and now in failing to explode. :-)
- deleted 3mo ago

fastball 3mo ago

Re-light seems to be one of their biggest remaining obstacles in a lot of these flight tests.