Starship Flight 7
spacex.com644 points by chinathrow a day ago
644 points by chinathrow a day ago
Looks like second stage broke up over Caribbean, videos of the debris (as seen from ground):
https://x.com/deankolson87/status/1880026759133032662?t=HdHF...
https://x.com/realcamtem/status/1880026604472266800
https://x.com/adavenport354/status/1880026262254809115
Moment of the breakup:
Preliminary indication is that we had an oxygen/fuel leak in the cavity above the ship engine firewall that was large enough to build pressure in excess of the vent capacity.
Apart from obviously double-checking for leaks, we will add fire suppression to that volume and probably increase vent area. Nothing so far suggests pushing next launch past next month.
Reminds me of one of NASA's reckless ideas, abandoned after Challenger in 1986, to put a liquid hydrogen stage inside the cargo bay of the Shuttle orbiter [0]. That would have likely leaked inside that confined volume, and could plausibly have exploded in a similar way as Starship.
[0] https://en.wikipedia.org/wiki/Shuttle-Centaur
- "The astronauts considered the Shuttle-Centaur missions to be riskiest Space Shuttle missions yet,[85] referring to Centaur as the "Death Star".[86]"
I wonder if it's related to the loose panel flapping about at the left of the screen here: https://youtu.be/qzWMEegqbLs?si=aUlI6zfkH3bZCmVm&t=111
This sounds like one of those "and also" things. I'd say you add fire suppression AND ALSO try more to reduce leaks. It's got to be really difficult to build huge massive tanks that hold oxygen and other gases under pressure (liquid methane too will have some vapor of course). Are leaks inherently going to happen?
This is meant to be a human rated ship of course, how will you reduce this danger? I know this stuff is hard, but you can't just iterate and say starship 57 has had 3 flights without leaks, we got it now. Since I have no expertise here, I can imagine all kinds of unlikely workarounds like holding the gas under lower pressure with humans on board or something to reduce the risk.
This might be one of those components where it just needs to be built without problems, and improved safety means fixing individual design and manufacturing flaws as you find them, until you’ve hopefully got them all.
This can work. Fundamental structural components of airliners just can’t fail without killing everyone, and high reliability is achieved with careful design, manufacturing, testing, and inspection. I’m not sure if a gigantic non-leaky tank is harder to pull off that way, but they might have to regardless.
We’re going to have to accept that space travel is going to be inherently dangerous for the foreseeable future. Starship is in a good position to improve this, because it should fly frequently (more opportunities to discover and fix problems) and the non-manned variant is very similar to the manned variant (you can discover many problems without killing people). But there are inherent limitations. There’s just not as much capacity for redundancy. The engines have to be clustered so fratricide or common failure modes are going to me more likely. Losing all the engines is guaranteed death on Starship, versus a good chance to survive in an airliner.
All other practical considerations aside, I think this alone sinks any possibility of using Starship for Earth-to-Earth travel as has been proposed by SpaceX.
High reliability of airliners is achieved by having redundancy of all critical parts. The idea is no single failure can cause a crash.
For example, if system A has a failure probability of 10%, if A is redundant with another A', the combined failure probability is 1%.
That of course presumes that A and A' are not connected.
Yes for systems, not always for structure. A failed wing spar means everybody dies. For real-world examples, there were two 747 crashes caused by improper repairs to a rear pressure bulkhead or aircraft skin. When the repairs eventually failed, the explosive decompression caused catastrophic damage to the tail in one instance, and total structural failure resulting in a mid-air breakup in the other.
The response to this was to make sure repairs are carried out correctly so the structure doesn’t fail, not to somehow make two redundant bulkheads or two skins.
Lindbergh's Spirit of St Louis had the main fuel tank directly in front of him. This was in spite of his primal fear of being burned alive. In some airplanes you sit on the fuel tank.
Given that a) most human rated rockets have had 0 flights before use, and b) I'd expect each starship to have at least 10 flights, and at least 100 in total without mishap before launching, the statistics should be good
I don’t think (a) is true. The Shuttle flew with people on its maiden voyage, but that’s the only one I can think of.
(b) is true and should make it substantially safer than other launch systems. But given how narrow the margins are for something going wrong (zero ability to land safely with all engines dead, for example) it’s still going to be pretty dangerous compared to more mundane forms of travel.
Most rockets flew test flights before sticking people inside the same model, but most rockets are also single use and so each stack is fundamentally new.
A future starship could plausibly be the first rocket to fly to space unmanned, return, and then fly humans to space!
I'm not sure there's fire suppression effective enough for this type of leak (especially given rocket constraints)
Aerospace fire suppression is generally Halon, which would purge the cavity with inert gas.
Actually the Super Heavy (first stage) already uses heavy CO2 based fire suppression. Hopefully not that necessary in the long term, but should make it possible to get on with the testing in the short term.
What is a long term solution for this? Is there something more than "build tanks that don't leak"? I'm sure spaceX has top design and materials experts, now what ;-).
I think its likely not the tanks but rather the plumbing to engines and the engines themselves leaking (sense lines, etc).
Next engine revision (Raptor 3) should help, as it is much simplified and quite less likely to leak or get damaged during flight.
That's interesting
However if you see the stream you can see one of the tanks rapidly emptied before loss of signal
It seems this was not survivable regardless of fire or not
It might not even be about fire suppression. Oxygen and different gases can pool oddly in different types of gravity. If oxygen was leaking, it may be as simple as making sure a vacuum de-gases a chamber before going full throttle.
We know nothing, but the test having good data on what went wrong is a great starting point.
Replying to this comment so people can see the incredible video of the breakup taken from a diverting aircraft:
https://www.reddit.com/r/aviation/comments/1i34dki/starship_...
If you can displace the oxidizer/air remaining in the volume why not.
The initial tweet says:
> we had an oxygen/fuel leak
If that's correct, then you can't just remove air. The only option would be to cool things down so it stops burning.
If it was really an oxygen/fuel mix burning I don't think you can do much of anything to stop that.
If you cooled the mixture at low enough temperature, you'd stop it from burning (like when you pour water on top of a camp fire), but it's not clear how you're supposed to do that in a spaceship where you can't carry a few tons of water for your sprinklers.
> If you cooled the mixture at low enough temperature, you'd stop it from burning (like when you pour water on top of a camp fire), but it's not clear how you're supposed to do that in a spaceship where you can't carry a few tons of water for your sprinklers.
Also water would make it hotter, given this is liquid oxygen.
It's not liquid at the point of ignition, that's the thing: if you mixed liquid oxygen and fuel nothing would happen expect the fuel would freeze. For a fire to take place the temperature must reach the fire point temperature, and if you manage to get your fire below this temperature then the fire stops. I don't know how low this temperature can be when the oxidizer is pure oxygen and maybe it's so low water wouldn't be enough, but then you can imagine using other fluids. The problem being the mass burden it adds to a spacecraft, I'm not it'd make any sense given that such q leak should happen in the first place.