SpaceX Starship SN3 Prototype Fails Cryogenic Pressure Test

The SpaceX Starship SN3 prototype fails its cryogenic pressure test.

Elon Musk speculates there could have been a test configuration mistake. This might mean different sections or tanks would need pressurization at different times.

SOURCES- BocaChica Gal, Las Padre, Marcus House, Elon Musk Twitter, Austin Barnard Twitter
Written By Brian Wang,

37 thoughts on “SpaceX Starship SN3 Prototype Fails Cryogenic Pressure Test”

  1. And the sooner we start, the better off we will be. Getting to Space (NOT Mars!) is crucial for our Earth. Most disagree that it is inherently, thus eventually, cheaper in Space. So they don’t work for it.

  2. To have the welders live in space would hardly be cheaper, unless we are speculating about a future with significantly more advanced space tech than 2020. You indicate that it would be cheaper to make in space, but really mean that one day, in the future, after a lot of development, it would be cheaper to make in space.

  3. An old boss’ brother was an underwater welder. He was on call, getting paid, in case a heli was coming to take him offshore to an oil platform.
    But, what if the welders wanted to be in Space?

  4. Making this in space would not be easier.
    The commute for the welders alone would be equal in cost to the entire current project.

  5. I don’t know. I’m looking at the tank configuration such as at (or any of the other google images for “starship tank configuration”), and maybe I’m not mentally mapping it correctly since this is a prototype, but ~~that frosty part at the top looks too small to cover the whole upper tank. And the portion under the frost line looks too long for the lower tank. So it doesn’t look like a lower tank failure to me.~~

    edit: On 2nd look, you may be right. If I look at the diagram without the payload section, and the frost line is right down to where the top tank starts curving inward, and the tank proportions or placement are a bit off, then that sort of fits. /edit

    I’m not ruling out a faulty valve, but the production valves should be rated for LN2, I think.

  6. There’s just the upper and lower tank. We saw where the upper tank ended because of the frost line at its bottom edge. The crumpling was below that, where the lower tank started. That’s below the Common Bulkhead. They also had to pause after previously loading cryo LN2 into lower tank to pressure test it, and that was allegedly due to a valve problem according to Musk’s own tweet. So from that I’d say the likelihood was that valve leaked and caused loss of pressure in the lower tank, which caused it to crumple under weight of LN2-filled upper tank.

  7. BTW, my orig point was not that tanks can’t *explode* in Space, it is that they can’t *implode*, given an outside vacuum.

  8. Didn’t look like a lower tank failure to me. The distortion started near the middle. And in any case, their valves should be rated for cryogenic temperatures. Probably as low as LN2, since they likely need it to flush and cool the tanks before filling.

  9. With methane, there’s an extra complication that you’d usually flush the tank with CO2 first to prevent an air-fuel mixture. Then, IIRC, they cool the the tank with a small amount of liquid methane, and only then load the liquid in bulk. But the CO2 condenses at these temperatures.

    In LNG carriers that’s not an issue, because they can afford sturdier tanks. Here it could be a problem. But if they use liquid nitrogen instead of CO2, they should be ok, and they should be able to flush and cool in one step. The nitrogen vapor should provide the pressure they need – unless they let too much of it vent out.

    With oxygen, it should be simpler. But likely still at least a two-step process. First cool and pressurize the tank with a small-ish amount near boiling temperature, then fill the liquid at the target temperature.

    Though for this test, I guess they were only using LN2? So my theory is still some sort of imbalance between the venting rate and feed pressure.

  10. Probably couldn’t happen on Mars because there isn’t enough atmospheric pressure to crush anything more substantial than a balloon.

  11. Not truly an implosion – more like a collapse of the lower tank due to insufficient pressurization, which is required in order for it to support the weight of the fully loaded upper tank. That lower tank may have suffered a pressure loss due to a leaky valve. Note that immediately before, they’d been forced to halt the test due to a valve problem, following their pressure test of that lower tank using cryo LN2. That earlier loading of cryo LN2 into the lower tank may have subsequently caused a valve to freeze and become leaky, thus later causing a loss of pressurization in that lower tank, so that it collapsed under the weight of the upper tank which was being loaded with cryo LN2.

    Perhaps in the future, it may be more prudent to do the cryo portion of the test onto the upper tank first, before doing the same to the lower tank. At least then any problem of any valve(s) freezing on that lower tank with associated loss of pressurization would not happen ahead of the loading of the upper tank. Either that, of they need to put more valves on that lower tank to safeguard its pressurization during the critical period of loading the upper tank.

  12. They seem to really be able to bang these out quickly. Just a minor setback. Though this one sounds like it might have involved some carelessness.

  13. Maybe it is healthy for people to see such ‘failures’ and realize that they are the price of less ossified and more dynamic engineering and development. At this rate, Musk is going to make SLS irrelevant before it ever gets off the ground, and at a tiny fraction of the price.

    It kind of reminds me how they have to remind people that landing the Falcon 9 first stage booster is just a secondary objective in their launches. Failing to land a booster is seen as a failure when all other launch companies ‘lose’ 100% of them because they just toss them. I think SpaceX being so successful in dominating the launch market while having such apparent ‘failures’ is overall a good thing.

  14. Brett is correct! Bill Nye used to do this on stage with a heated oil drum with a little water in the bottom. Cap it and remove the blowtorch and within five minutes, it looked like King Kong crushed his pop can! Once the water vapor flashed back to a liquid state outside air pressure crushed it with 14.7 psi from every direction! I wonder if this was some elaborate Elon Musk “Engineer interview hiring prank”?

  15. Yeah, I get it.

    What I mean is that some tests are better done behind closed doors. Checking the tank, pipes and pumps resistance to pressure ought to be done before going into any place where the public eyes can ogle.

  16. I thought that was failed electrical, forcing over use manually of heater switch, failure and fire.

  17. Normally I wouldn’t expect loading cryogenics to result in a partial vacuum. But then I remembered that they’re using especially cold cryogenics, to get higher density. That means their cryogenics can absorb a substantial amount of heat without their vapor pressure reaching atmospheric pressure. Normally cryogenics are used at or near their boiling point, and their vapor pressure is high enough to prevent them from causing a vacuum by cooling gas that’s already present in a tank.

    But used especially cold the way they are, yes, you could see them cooling the pressurizing gas enough to reduce the pressure below ambient without enough boil off to replace the lost pressure.

    They will probably have to substantially pressurize the tanks prior to loading, and then pump the fuel and oxidizer in against that pressure.

  18. The tests are not public. They are being filmed from kilometers away.

    Maybe SpaceX should lease Area 51?

  19. Not this exact failure mechanism, no.
    But tank failure due to improper pressure control can and has happened in space. c.f. Apollo 13

  20. This sort of reminds me of sometimes that happened with Atlas rocket tests/launches. I think. I may not be remembering correctly though. Like, too much in the top and not enough in the bottom for for proper structural integrity.

  21. This is why rocket builders are so fanatic with validation and double checks, resulting in delays and cost overruns (but that’s not the only cause).

    I take that Starship, being a beast in a whole other league, may need more time than Musk’s current estimations, and the reason why Dragon 2 and FH/cislunar dragon make sense.

    In any case, they should be more careful with any public tests. They are making the wrong kind of PR with so many failures on a short time, and public perception is a valuable resource too.

  22. This is speculation but I’d imagine the implosion effect occurs as a result of the inertia of the rapidly escaping gas pulling a vaccum on the rest of the tank, similar to how exhaust scavenging works, and/or rapid elastic rebound of the thin tank walls causing the inward crushing. (edited for stupid type-o)

  23. We’re they past the point in the test protocol for applying simulated thrust with hydraulic rams? If so, they at least have that data. Regardless, the lower structure held the tank pressure without rupture.

    The intermediate bulkhead between tanks appears to have also held against what appears to be a partial vacuum in the upper tank. A faulty transfer operation removed contents from the upper tank, which resulted in vacuum?

  24. It wasn’t SpaceX’s fault… I was using my dark side of the force powers to Crush the tank while watching it live from sPadres YouTube account…

  25. It will be interesting to see how they fix problems like this on reentry…when the reentry tiles are getting heated to thousands of degrees… right now … it’s looking like they would need to put another lay of sheet metal over the one side to have something to bolt the tiles to….

  26. that would really suck if it happened on Mars… sorry guys I forgot to pressurize the tanks correctly then kaboom… I guess we better start engineering the shit out of growing Mars potatoes fertilized with human waste… That might help with the rootbeer mug Frost on the outside..

  27. A previous test also looked like an implosion to me. Which means either it isn’t, or they’re repeating the same mistake. My guess is the internal pressure drops because of the cooling, without enough gas to compensate for the temperature. But the question is – does that happen before or after the failure?

    A possible scenario is: failure –> rupture without complete RUD –> (partial?) venting –> internal pressure drops, temperature is still cold –> collapse of the remaining structure, looks like implosion.

    edit: Just saw the video. Didn’t notice any significant venting before the implosion this time, except for the intentional stuff. Didn’t look like there was a rupture. So maybe insufficient feed pressure?

  28. No, you could never stiffen the tank enough to survive any significant negative pressure and still be light enough to fly.

    You want it stiff enough to stand while empty, but standing while drawing even a fraction of a PSI of vacuum is just out of the question.

  29. Clearly an implosion failure, the testing procedure accidentally caused the tank to have a negative gauge pressure, and no lightweight tank could sustain even a small fraction of a PSI of negative pressure.

    This sort of failure doesn’t imply anything at all was wrong with the rocket itself, it was a sequence of operations mistake.

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