The investigation team identified several credible causes for the COPV failure, all of which involve accumulation of super chilled LOX or SOX in buckles under the overwrap. The corrective actions address all credible causes and focus on changes which avoid the conditions that led to these credible causes. In the short term, this entails changing the COPV configuration to allow warmer temperature helium to be loaded, as well as returning helium loading operations to a prior flight proven configuration based on operations used in over 700 successful COPV loads. In the long term, SpaceX will implement design changes to the COPVs to prevent buckles altogether, which will allow for faster loading operations.
SpaceX is targeting return to flight from Vandenberg's Space Launch Complex 4E (SLC-4E) with the Iridium NEXT launch on January 8.
Are COPVs a universal thing in rocketry? Or has SpaceX actually loaded fuel into its rockets over 700 times?
> Or has SpaceX actually loaded fuel into its rockets over 700 times?
This. SpaceX has done development test cycles, and for each launch performs stage acceptance tests at McGregor Texas and both "wet dress rehearsals" (now generally skipped) and static fires at their launch pads. All of these operations involve loading and unloading helium and LOX.
SpaceX hasn't flow anywhere close to 700 flights but a lot of testing would involve fuel loading so the 700 figure sounds high but not unreasonably high to me.
They've done almost 30 Falcon 9 launches now. If there are 4 per vehicle and 3 loads per launch, that's about 360 loads just from that.
For the broken link, there's just a stray semicolon at the end. Working version: http://spaceflight101.com/falcon-9-amos-6/wp-content/uploads...
That's just for the actual production flights, as well. Add in all their testing (Grasshopper, etc), and I have no problem believing they have tanked propellants on over 700 occasions.
...concluded that one of the three composite overwrapped pressure vessels (COPVs) inside the second stage liquid oxygen (LOX) tank failed
...failure was likely due to the accumulation of oxygen between the COPV liner and overwrap in a void or a buckle in the liner, leading to ignition and the subsequent failure of the COPV.
.... corrective actions .. short term ... changing the COPV configuration to allow warmer temperature helium to be loaded ... long term, SpaceX will implement design changes to the COPVs to prevent buckles altogether
Next launch on January 8th.
And the second is that their wrapping method allows for the creation of voids between the inner aluminum tank and the carbon fiber wrap. I can certainly imagine how that could happen with carbon fiber prepreg (it's a prewoven fabric which maximizes strength by pre-laying out the various ways the fiber goes through it) but if you were to spool on straight up fiber that would make it easier to be conformal.
I wonder if other people do the 'tanks within tanks' architecture and if so how they avoid voids and buckles in their overwrap.
SpaceX was pushing the loading speed to expand the flight window. The update (and Ms. Shotwell a few months ago) indicate the short term fix for this is to slow down the propellant loading to allow the He to warm up a bit before LOX arrives... Which is a long way to say that it's likely other companies have not pushed the envelope far enough to encounter this voids and buckles problem.
The update also says they will eventually adjust their COPV construction to eliminate this problem and return to rapid propellant loading, but I doubt we'll hear anything about HOW they improve it. A not insignificant amount of SpaceX's "secret sauce" is in their composits manufacturing (case in point the enormous ITS LOX tank recently tested.)
I imagine the reason it's not done this way traditionally is that it'd be a pain to fabricate.
Turns out COPV's have a tendency to explode semi randomly, with failure modes that are not fully understood
The worst kind of bug is the intermittent one that you can't reproduce or see in logs. With only 35-55 milliseconds of metrics leading up to the event and nearly obliterated evidence, it seemed nearly impossible they would be able to nail down the exact cause.
Critics have pointed out risks in SpaceX's method of loading supercooled fuel. Accidentally forming solid oxygen around carbon fibers from a buckling overwrap is an example of this.
There are benefits, but they will need to find and prevent all these possible edge cases exposed by the new method.
I wonder if supercooled propellants are really worth it. It seems like a huge risk in exchange for a small performance increase. Hopefully this will be the last vehicle loss they suffer from it.
PS: High launch costs set up a cost escalation as satellites are so expencive they can't fail. Which means launches need a really high success rate. If you could get 10,000kg to LEO for say 1 million but had a 40% failure rate you would see a very different approach with much lower overall costs.
For this particular problem, the risk to the payload will be eliminated by not attaching it for the static fire. Any risk during the actual launch would still affect the payload, though.
To put it in concrete terms, if insurers decide that SpaceX is significantly more dangerous to its payloads, then launch insurance for satellites using SpaceX rockets will become significantly more expensive.
Disclaimer: I don't know shit about the space industry, so don't waste your time.
FT can get 30% more mass to LEO. That is a pretty big performance increase, especially considering that it enables SpaceX to carry the maximum payload of v1.1 in expendable configuration and still land the FT rocket. Even if we assume that half of that performance boost came from the other improvements, 15% is a significant increase.
Shaving just a little weight (especially on the 2nd stage) or squeezing out just a little more performance can have dramatic differences in mass to LEO.
The question is how much this will increase overall operational cost. Up until this year or so, it has seemed that SpaceX has been willing to compromise on performance to get lower overall operational cost and reliability.
I'm a bit worried that they've started to go the other way with some of the improvements they've made this year.
After the Ariane 5 first-launch failure, it was well over a year before it flew again.
Once the redesigned tanks come in, it's likely that they'll go right back, because little holds aren't uncommon.
However even if we did somehow run out of Helium entirely, once SpaceX switches to Methane fuel (as they plan to do for the ITS) they won't need it anymore. Currently it's used to pressurize the tanks, but Methane does that for itself. It would mean speeding up development of 'small' methane launch vehicles presumably, but that's it.
Per the other comment, no other noble gas has a low enough boiling point to remain a gas at LOX temperatures...
And given that the nearest natural source of helium is Jupiter, that is a little concerning.
An estimated 54 billion cubic feet (1.5×109 m3) of helium was detected in Tanzania in 2016
We already rely on nuclear reactors to get several elements that are used in radiotherapy. IIRC there was a major shortage of medical isotopes a few years ago when a Canadian reactor that used to supply most of them was shut down.
Of course, it will be expensive, so no more cheap helium balloons for our grandkids. For specialized applications, though, we can afford some artificial helium.
Sun is closer and produces helium all the time, but less practical to harvest it from.
"breaking fibers or friction can ignite the oxygen in the overwrap"
I would like to see at least this ignition source duplicated.
There is still no cause listed on Wikipedia.
> Industry experts described the total loss of contact with the satellite as a highly uncommon event.
This one was built by Russians for the first time. It looks like they went back to a domestic built one with SpaceX and it blew up. That's some bad luck :/
They've got enough money out of insurance to build themselves a new satellite, the problem is that they need that satellite yesterday, not today.
On the other hand, SpaceX isn't living off poor blokes who were hoodwinked by a starry-eyed agent. Their customers are professionals with lawyers and accountants taking care of things, so I don't feel that SpaceX is particularly unethical.
A quick google search for `liquid helium rocket` introduced me to pressure-fed engines . A pressure-fed engine uses liquid helium, and is a replacement for a turbopumps. Since the Falcon 9 uses turbopumps, I don't understand what the liquid helium is for.
If I had to guess, it sounds like a Falcon 9 has a pressure-fed engine AND a turbopump. On a car, that'd be kind of like using both a turbocharger and a supercharger, which sounds complicated.
Falcon-9 has no pressure-fed-only engines, all 10 engines are fed by turbopumps.
This gas need to be as inert as possible, hence helium. Another noble gas could in theory be used, but I think price is the reason.
Alternately, if the propellants allow, it's possible to use those in gaseous form for pressurization (by passing some of it through a heat exchanger). This increases the weight of pressurant gas wasted but it saves the weight of the Helium system, and the complexity, so ultimately it's a big win. Unfortunately, this doesn't work with kerosene so the Falcon 9 needs a Helium system.
However, this kind of oxygen-gas pressurization is exactly what's planned for SpaceX's next-generation oxygen-methane rockets.
variations in the density of fuel entering the combustion chamber lead to variations in thrust which can lead to pogo oscillations.
1. How often does this happen?
2. Hoe many tests did SpaceX do before the first FT launch?
Considering that most rockets don't use supercooled fuels, I would expect insane tests (they can't rely on NASA's historical data).
It's been exactly two.
The fact that it's misleading is simply a fact. It's only an ad hominem if they ascribe malicious intent, which they did not.
Also, what phrasing would you have preferred? "More than one" is the most accurate and least subject to misinterpretation, but then of course you'd still say it's misleading if the answer turns out to be two. If I knew the exact number I would've just said it. The point of using indefinite quantifiers is to convey uncertainty, it is not to mislead.
So no, you shouldn't have been bolder with a public post.
I disagree; SpaceX has a clear interest (and a well-established track record) of presenting things in a way that bolsters their image. Outside experts could provide critiques of the report: What represents bad luck, what is trivial, and what is a serious error; where is SpaceX being straightforward and where are they spinning things; where are the gaps, where are there alternative analyses of the same data, and what seems solid.
That is a big reason why journalism is important: It provides context and other voices.
Incidentally, any time you post something that isn't fully saturated with the SpaceX Kool-Aid, you get a strong reaction. Look at all the comments and the downvoting over a pretty mundane detail and a common concern: Don't link to a press release. I didn't even criticize the Great and Powerful Wizard or his rocket ships.
To be clear, I don't care about the votes, but I think the overall response says more than the comments.
I didn't downvote your comments but I can see why you got them: you provided an NYT article that wasted readers' time.
Yes, it's wise to be skeptical of "press releases" to avoid spin but your rigid adherence to avoid-press-releases-at-all-costs put you on autopilot and caused you to link an article that was worse than the press release.
Now, you think the downvotes are about disagreeing with your principles about press releases when it may just be downvotes about that specific NYT article that added no value.
Sure, when Apple makes a press release, readers would be better off skipping their corporate marketing fluff and look at the Ars Technica writeup that will be more critical. However, the NYT writeup of SpaceX's accident report isn't an analogous example value-added journalism. (The newswriter Kenneth Chang is not a rocket scientist and can't offer any expert counterweight to the press release.)
> you think the downvotes are about disagreeing with your principles about press releases
Journalism is not regurgitating press releases.
A journalist would have tried to find experts able to comment on the SpaceX release to reveal information that was obfuscated or omitted.
The NYT article you linked was not journalism. If you want to wave the "do not link to press releases" banner, do not link to press releases :D
If you linked to an article that provided such things, I'd see your argument. But you linked to something that just regurgitated the press release, and said it was better than the press release. If outside experts didn't provide critiques, the fact that they could is meaningless.
It also produced a large quantity of nonsense. WAPO kicked that off with speculation of "sabotage."  By the time that stuff had finished ricocheting around the echo chamber it was SPETSNAZ snipers. Today WAPO has finally grounded out it's "Russian's hacked the US power grid" fiction. 
It would be nice if Elon could take a few minutes and install some grown-up editors at his paper. It's turning into a tabloid.
* Oh dear, I've mixed up my celebrity billionaires... Yes, Elon would have to get Bezos to fix the paper.