This is an interesting announcement, in the context of Elon’s Mars speech next week in Guadalajara:
At this stage of the investigation, preliminary review of the data and debris suggests that a large breach in the cryogenic helium system of the second stage liquid oxygen tank took place. All plausible causes are being tracked in an extensive fault tree and carefully investigated. Through the fault tree and data review process, we have exonerated any connection with last year’s CRS-7 mishap.
Makes sense, but still doesn’t sound like they’ve gotten to the root cause.
Never heard of helium making a fireball. The debris might have punctured something though I guess.
I think the theory that the propellant hoses leaked made more sense to me.
The fireball seemed to originate outside the rocket.
“The fireball seemed to originate outside the rocket.”
That is still possible, if whatever punctured propellant tanks punctured both those *and* the vehicle’s skin, spraying out enough Kerosene that when LOX and hot debris hit it, the mix ignited.
One thing this does emphasize to me is the wisdom of the ULS ACES stage having no need for such pressurizing gasses, or high pressure tanks for them. It’s *more* obvious in desgn when using LHy/LOX, but now seems wise in all such stages. Maybe we will see this reflected in future mods for Falcon 9, Falcon Heavy, and BFR upper stages, and possibly for New Glenn as well.
Sorry, …I meant to say “ULA ACES Stage”.
There was a pretty detailed analysis of the video posted recently which seems to be confirmed by this announcement. It’s worth a watch: https://www.youtube.com/watch?v=EhdQPaABFK0
The upshot is that the high pressure helium tank is inside the Lox tank and a rupture would have burst the Lox tank and in particular, the common bulkhead with the RP-1 tank below it.
This is similar to what happened in the in-flight failure (which they attributed to a helium tank strut failing under g-loading) causing the helium tank to leak into the Lox tank.
“The fireball seemed to originate outside the rocket.”
My assessment of the public video as well. The illumination pattern, extreme speed consistent with an already mixed explosive material, and an object thrown apparently almost straight up from the initial explosion, all don’t seem to fit with an O2 tank burst from an He tank failure. If the He tank failure was forceful enough it might rupture both fuel and O2 tanks, the ignition following. Kerosene aerosol from a leaky hose meeting an ignition source looks to me like a much better fit. And I wouldn’t be at all surprised if a He tank failed as a result of the shock waves or fire.
A helium tank rupture causing a spike in O2 tank pressure would likewise send the pressure up the piping and out to the propellant feed lines. The common bulkhead rupture would likewise send a pressure wave up the fuel lines as well as the oxidizer lines. The weak point is almost certainly going to be the connector between the tower’s umbilicals and the rocket, since they have disconnect fittings. The pressure would cause the fitting to fail, blowing both fuel and oxidizer all over the side of the rocket, and the spray might well cause an electrical short right at the connector.
One possible cause IMHO; a COPV (carbon fiber tape wrapped) ignited. It’s in LOX, and carbon fiber is quite flammable in LOX. As the COPV wrap combusted (which would be extremely fast in pure LOX), the COPV would burst, releasing helium.
I’m thinking the possibility that someone shot it has not been ruled out?
Someone from ULA?
Trump did it to help Russia.
Elon must be viewed as an economic enemy of Russia, and not just for SpaceX.
Hell, could be Russia. Elon’s disrupting a lot of peoples’ business plans.
I haven’t heard that anything has been ruled out.
People are focusing on the setback to SpaceX as being motivation for possible sabotage but what about the payloads?
The payload was AMOS-6, owned by Spacecom. Spacecom is an Israeli company that was in the process of being bought by the Chinese – and the deal was contingent upon the sucessful launch of AMOS-6. The loss of AMOS-6 tanked Spacecom stock (50% decline) and torpedoed the deal.
I can imagine several suspects, including anyone who decided to make some $$$ by placing major puts on Spacecom in the futures market.
My guess; if this is sabotage, I think it’s more likely than not that SpaceX wasn’t the target.
I’m not an engineer, but a COPV failure has been my idea of a worst-case scenario, since that might imply a need for a redesign.
Could a COPV have burst in such a way that it ruptured the side of the stage as well as the common bulkhead, giving the illusion that the explosion began on the outside of the vehicle?
Just back of the envelope look at the energy involved in the helium storage system. Falcon 9 upper stage has Isp of 340 seconds at 161000 lbf thrust and burns for 375 seconds, so burns just over 80,000 kg of propellant. At usual densities, that’s around 80 cubic meters of volume to pressurize. Probably pressurized (within a factor of 2 or so) to around 4 atmospheres, 400kPa, but stored at around 30MPa. Also probably stored around 90K and used around 270K, significantly reducing the storage volume. Even with that, volume in the vessels storing the helium would be in the rough neighborhood of 0.4 cubic meters. Still, P*V product (energy) stored in the bottles is around 12MJ — or about 12 sticks of dynamite.
Helium bottles stored at cryogenic temperature aren’t new — they were on Saturn. Cryogenic COPV are newer but by no means is this the first time they’ve been used, so rushing to jump on SpaceX because of this would be absurd. But as with a lot of vehicle systems, the amount of energy involved is worthy of respect.
I do like the Space Age’s definition of the word anomaly; our rocket blew up.
I’ll give Musk credit; he called it a fireball, not an anomaly.
As for using “anomaly” as SpaceX did, we could apply the word “anomaly” to other things and see if it sounds as much like political doubletalk;
The patient had an anomaly (the patient dropped dead).
My neighbor’s house had an anomaly yesterday (there’s a big smoking crater where it used to be).
Flight 123, with 321 passengers aboard, had an anomaly. ( it made a very large crater, and there’s nothing left larger than a breadbox)
Two of the most famous anomalies at sea are the Costa Concordia and the Titanic.
New Orleans had an anomaly (Otherwise known as Katrina).
What if it goes the other way?
The patient had a rocket blow up.
My neighbor was making a right hand turn and had a rocket blow up with a bicycle.
Ugh, I thought that test went well but it was a total rocket blow up.
They’re saying the debris indicates a helium tank rupture.
Perhaps the earlier strut failure had a similar cause?
If the helium tank ruptured, was it the cause of the explosion, or the effect?
I don’t remember if what I read said. The context was just that the debris indicated it ruptured. I just assumed they were suggesting that as a cause.
As I understand it, SpaceX is saying they detected a rupture in the helium system for the LOX tank 0.1 seconds prior to the explosion.