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What happened to the SpaceX Starship SN11?

As per the live streams held on YouTube, I want to know what really happened to SpaceX Starship SN11

The live streams show a lot of smoke and others show some camera footage, even others say it blew up in the sky. And other people even say that there was an issue with the 2nd raptor engine

What is really going on here?

  • Did it blow up in the sky?
  • Did it blow up on the launchpad?

Why did it crash?

(my speculations)

  1. Computer code error

    SpaceX's software resulted in the SN10 flight being successful (even though it came down with quite a bump!) so we can assume that SpaceX used the same code but altered it a bit so they instructed the computer to reduce the velocity so it wouldn't come down like SN10.

    However there was an error with the code

  2. Raptor/s issue/s

    Or we can assume that the computer ran the code correctly, but there was a raptor issue as shown by the fire here

  1. It was caused by the fog

    Or we can also assume that everything went well but the landing wasn't possible due to the fog. The computer could not calculate and made a botched landing attempt

  2. Or there was/were some other issue/s

So which of the four was it?

  1. Computer code error
  2. Raptor issues
  3. Bad weather caused by the fog
  4. Some other problem/s

Other suggestions and answers other than the given 3 are also welcome!

Detailed answers would be helpful :)

Đαrkraι
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    "I have heard that..." and "I have read that..." and "People say that..." questions sometimes get pushback because the cite unnamed sources of dubious information and then demand fact-based answers. If you have a source of information that is reliable, please go ahead and name it and include a quote. Btw the > mark is used for block quotes of text from sources, not for highlighting or bullets. That's how you can indicate when you are quoting your sources. Thanks! – uhoh Mar 30 '21 at 14:32
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    @uhoh Thanks! It helps that you informed me about the quote mark – Đαrkraι Mar 30 '21 at 14:56
  • Pretty much confirmed that on engine relight, 2 of the 3 failed, triggering the FTS to panic, destroying the vehicle. 1 fail was "expected", it misbehaved on the way up. – CuteKItty_pleaseStopBArking Mar 30 '21 at 20:16
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    Which live streams show a lot of smoke? All the live streams I have seen showed a lot of absolutely nothing because of the extremely dense fog at Boca Chica yesterday. – Jörg W Mittag Mar 31 '21 at 12:26
  • A little concerned about their piping welds, and QC before they went to full scale. They fire up, then shut down at high altitude (where it is very cold), then attempt a restart. Contraction and expansion, particularly with different metals? They may need to literally cover their backside a bit more. – Robert DiGiovanni Mar 31 '21 at 13:16
  • @PcMan Everything I'm seeing (e.g. Scott Manley) says it's confirmed that FTS did NOT fire. – Harabeck Mar 31 '21 at 22:30
  • @PcMan Nothing you listed there has been confirmed at all, and some of it doesn't make sense. We only have the video showing one relight - the video is delayed and not a reliable source. FTS exists to prevent the vehicle from deviating unsafely from the danger zone, and falling near the ground with insufficient propulsion is not a hazard from that perspective. And FTS charges should unzip the tank without making it confetti. – Saiboogu Apr 01 '21 at 13:28

4 Answers4

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What happened to the SpaceX Starship SN11?

It's fairly apparent that what did happen is that it exploded in the fog during its descent. It's far too early to know why this happened. Lots of people who were there reported seeing falling debris. Eric Berger at arstechnica.com wrote

All we really know for sure is that at 5 minutes and 47 seconds into the flight, one of Starship's three Raptor engines relit to begin the final landing sequence, and then the engine-bay camera cut out in SpaceX's webcast. Contact with the vehicle was lost, at least in terms of live video pictures. Shortly after this, pieces of the Starship vehicle began raining down on the launch site, and there were reports of a series of small explosions.

Eric writes cautiously, and he rarely speculates or conveys unfounded rumors. (There are rumors galore on this.) Eric did report on one photographer he knows (Eric knows lots of people) who was on the scene and saw the thick sea fog. The photographer drove inland a ways where he might have a better view when the vehicle ascended above the fog. He did have that view; the linked article shows pictures taken by that photographer of the vehicle ascending above the fog and performing its belly flop. (Note: I am not posting those images here because those pictures are copyrighted by a professional photographer.)

Eric did make one implicit speculation in the article:

It is not clear whether the vehicle's flight termination system was activated to destroy the Starship before it veered off course. However, the remnants of the vehicle landed near their intended target.

The vehicle's automated flight termination system certainly is a possible culprit; the AFTS's one and only one purpose to make the launch vehicle explode. There are however many other possible causes for a launch vehicle undergoing rapid unintentional disassembly.

PearsonArtPhoto
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David Hammen
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  • It wasn't the FTS. Of that I am quite sure. A FTS failure should explode less, and is highly unlikely to happen just off the ground... – PearsonArtPhoto Mar 31 '21 at 15:52
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    I can't imagine it being the FTS either. It was directly over the landing pad, smack-dab in the middle of the exclusion zone, and only a couple 100m high. There was no reason to terminate it, it wasn't going anywhere it wasn't supposed to. – Jörg W Mittag Mar 31 '21 at 17:19
  • I will agree that there was no reason anybody would have sent a destruct command. However, off the top of my head I can come up with two rockets that suicided because of catastrophic failure. – Loren Pechtel Apr 01 '21 at 01:31
  • @LorenPechtel SpaceX uses an automated flight termination system. The AFTS can punch the big red button all by itself; intervention by a range safety officer is not required. – David Hammen Apr 01 '21 at 09:29
  • @PearsonArtPhoto There is a lot of scuttlebutt that it was the AFTS. But this is just scuttlebutt for now. Patience is a virtue; these investigations can take weeks, sometimes months, to complete. – David Hammen Apr 01 '21 at 09:32
  • @JörgWMittag The last callout shortly before the explosion was that the vehicle's altitude was 1 km. There was no callout that the AFTS had been safed, so termination via the AFTS cannot be ruled out. It of course also cannot also be ruled in; it's far too early in the investigative phase of a midair explosion to rule anything in. As I noted in my previous comment, patience is a virtue. – David Hammen Apr 01 '21 at 09:41
  • I have it on good authority that it wasn't the FTS system. I've heard from a good source that at least 5 SpaceX employees have confirmed it. What exactly what the problem is tricky... – PearsonArtPhoto Apr 01 '21 at 11:43
  • Others claim to have heard from good sources within SpaceX that it was the AFTS, @PearsonArtPhoto. And that gets to the heart of the problem raised by uhoh in his very first comment under the question: "I have heard that..." and "I have read that..." and "People say that..." There's too much of that going on right now. The right answer, at least for now, is the we (the general public) do not know what caused the incident, and I suspect that "we do not know" is currently the correct answer even within SpaceX. – David Hammen Apr 01 '21 at 12:17
  • Those rumors I haven't heard. Hmmm, guess I need to dig more in to that rabbit hole... – PearsonArtPhoto Apr 01 '21 at 12:18
  • @PearsonArtPhoto I too have contacts within SpaceX, but I intentionally have not asked them a thing. Currently all we have is hearsay. I have not seen anything in the open media about key data recording equipment having been recovered. That recovery could shed light on the AFTS imbroglio. Suppose it does turn out that the explosion resulted from the AFTS unzipping the tanks. Even if that turns out to be the case, that almost certainly wouldn't be the root cause. SpaceX is looking for that root cause because that is what they need to fix. Until they find it, "loose lips sink ships". – David Hammen Apr 01 '21 at 12:45
  • I will observe that I've heard people say that other people say that SpaceX people say it was FTS ... And I hear people say that they heard first hand from SpaceX people that it wasn't FTS. It's a small distinction, but in every instance the counter examples are more direct, less hearsay. – Saiboogu Apr 01 '21 at 13:31
  • @DavidHammen I don't understand your comment--I was saying it doesn't look like a situation where a human pushed the button but that it could be the rocket itself doing it. – Loren Pechtel Apr 02 '21 at 01:29
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Looks like SN11 most probably crashed. twtr screenshot

“At least the crater is in the right place!” ... “Something significant happened shortly after landing burn start. Should know what it was once we can examine the bits later today.”

My emphasis on "bits", taking it to mean (destroyed) bits of SN11. Looks like we'll know more about what actually happened perhaps later today.

BMF
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  • Another rumour says there was a problem with engine relight : they relight 3 engines because they need at least 2 working correctly, but only 1 engine relit correctly, which was not sufficient for proper attitude, so self-destruct was initiated. – Nimloth Mar 30 '21 at 17:42
  • @Nimloth Yeah, I think I read that somewhere. Supposedly, one of the engines was having trouble from the get-go as well. There are some images going around of a mangled, mid-air SN11 before impact, though not many due to the heavy fog. – BMF Mar 30 '21 at 17:51
  • I've seen people taking "bits" to refer to data (as in telemetry), but I suspect your interpretation is correct...why would they wait to look at telemetry? – Christopher James Huff Mar 30 '21 at 17:52
  • It's definitely been destroyed saw debris raining down through the fog. – Slarty Mar 30 '21 at 19:05
  • hey @BMF i have updated the question and i would appreciate it if you changed your answer – Đαrkraι Apr 01 '21 at 04:42
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    @C0D3X: Changing the question will not change the answer: SpaceX has only just begun collecting the pieces. Not even they know the answer. Investigations like this sometimes take years. It just happened this week. – Jörg W Mittag Apr 01 '21 at 13:18
  • @BMF Link those images? – Saiboogu Apr 01 '21 at 13:34
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We know for certain this was a mid-air explosion. Twitter user RGVAerialPhotograph, photo linked but not included here because I'm unsure of copyright, shows the pad is clearly intact, and the debris is spread to the north of the pad. I've also had it on good word from someone who would know that it wasn't the FTS system. It seems like whatever happened it was a true explosion, so mixed oxidizer and fuel with a spark lead to an explosion, in something that is roughly mixed correctly.

We know the nose cone is mostly intact (But unzipped), the tank is completely shredded. We know that the event happened when one of the engines attempted to ignite, most likely the third. The remains of the nose cone landed very close to the landing pad, so it was probably mostly on target.

We also know that the CH4 header tank, right in the middle of the rocket, is pretty much in two widely separated pieces. It therefore seems very likely that the first explosion happened there.

Whatever happened must have happened mostly from the south. The orientation of Starship when falling is the nose points east, the engine point west. Incidentally, the FTS is on the side pointing downward during the fall, which would not explain the debris cloud preferentially being north.

All of this being the case, I would say some oxygen somehow worked its way in to the header tank. That oxygen likely reached the engine, causing an explosion which traced its way upward to the header tank, that completely blew up.

PearsonArtPhoto
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A recent tweet from Elon says that:

Ascent phase, transition to horizontal & control during free fall were good.

A (relatively) small CH4 leak led to fire on engine 2 & fried part of avionics, causing hard start attempting landing burn in CH4 turbopump.

This is getting fixed 6 ways to Sunday.

Mark Omo
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wdtj
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