SpaceX Moves Past Explosion With New Launch Plans (cnn.com)

SpaceX plans to resume launching rockets as soon as next week, after completing an investigation into a spectacular launch pad explosion that destroyed a rocket and a satellite in September. From a report on CNN: The news comes following an in-depth investigation into the explosion of a rocket from SpaceX's September mission. The company said in a statement Monday the botched launch was due to a failed pressure vessel in a liquid oxygen tank. The vessel buckled, causing liquid oxygen to accumulate. It believes this led to friction, sparks and the explosion. SpaceX conducted the investigation along with officials from NASA, the Federal Aviation Authority, the U.S. Air Force and the National Transportation Safety Board. The Federal Aviation Administration will have to sign off on the report and issue SpaceX a license to launch. SpaceX appears optimistic it will be launching rockets again soon.

Comments

Good for SpaceX

[mykepredko]

I know I come across as somebody who knocks Mr. Musk, but we need more entrepreneurs like him pushing the barriers.

Re:Good for SpaceX

[nitehawk214]

Because nobody at ULA makes any money, and they certainly don't have taxpayer paid launches.

Might want to take a look at the dollar per payload on competing heavy lift platforms.

Re:Good for SpaceX

[gman003]

You can have $70M of your taxpayer dollars used on his rockets, or you can have $160M of your taxpayer dollars go to Lockheed Martin and Boeing. Your choice.

So:
* Cheaper by 55%
* Built entirely in America
* Doesn't give money to a country we're sanctioning
* No design elements from the 1970s
* Company is doing innovative things to drive down costs even more in the future
* Slightly more likely to explode

Seems like a good thing to me.

Re:Good for SpaceX

[Bruce Perens]

One might have more sympathy for ULA once they are capable of flying without Russian engines.

Re:Good for SpaceX

[Anonymous Coward]

You can do rocketry as ULA does; exactly like we've been doing for the past twenty+ years and have it cost exactly the same as it has for the past twenty+ years.

_Or_ you can invent new, _substantially_ more cost-effective ways of doing rocketry. Whenever you're doing something new in a high-energy field, there's a chance of explosive failure. (Remember Apollo 1?) Hell, explosive failure happens even when you're doing the same old thing. (Remember Challenger? Columbia?)

The only con SpaceX is revealing is the long-play ULA and others like them have been running on the American People. Rocketry can be cheaper, better, and require only domestically-sourced components. All that was required to make this happen was someone who gave enough of a shit to make it happen. This could have happened _decades_ ago, but didn't because the Big Aerospace Contractors were more interested in milking the government teat than providing the best value to the American People.

Re:Good for SpaceX

[ogdenk]

You honestly think Boeing and Lockheed haven't blown anything up and we've never experienced rockets exploding upon launch before when overpaid pork-barrel contractors are involved? Remember the Navy's kaputnik? Remember Challenger? Remember many test pilots killed in experimental planes? How about combat pilots killed due to the P-38's issues in a dive?

Stop being a shill. Rockets explode sometimes, especially ones that are innovative and new.

Re:Good for SpaceX

[Ol Olsoc]

One might have more sympathy for ULA once they are capable of flying without Russian engines.

That's a non sequitur. Parts is parts, and the Russkies make superlative engines. You don't have to start all over again for every company. NASA uses Russian engines too.

Re:Good for SpaceX

[Ol Olsoc]

You can have $70M of your taxpayer dollars used on his rockets, or you can have $160M of your taxpayer dollars go to Lockheed Martin and Boeing. Your choice.

This is kind of how this is supposed to work. There will always be a place for Government launches, and the place for private launch companies will expand. I cannot understand why so many people cannot understand that, unless they are looking to end rocketry altogether.

Re:Good for SpaceX

[ogdenk]

There's plenty of obvious innovation. If you can't see that, you're either stupid or trolling.

To be a death trap, they'd have to kill someone in it first. So far they have yet to kill someone unlike previous NASA contractors.

Re:Hope this is true

[NoNonAlphaCharsHere]

Ten minutes after Challenger blew up, the other engineers I worked with and I were saying to each other: "Watch, it'll come down to some idiot middle manager screaming "Whaddya MEAN I can't ship on time???". The thing about Rocket Science is: IT'S FUCKING ROCKET SCIENCE!!! Shut the fuck up about your pulled-out-of-your-ass ship date!

Would be nice...

[Rei]

... to actually get to see a detailed breakdown of the cause of the last explosion, rather than having to piece it together from bits and pieces of what's been said so far.

So far, it seems that there was (expected) supercooled liquid oxygen seeped into the CF reinforcing fibers on the helium COPVs (as was expected), which was just above its freezing point. They then began loading cold helium. Had the oxygen stayed liquid, it would have squeezed out (expected behavior). Rather, the oxygen wasn't able to seep out fast enough, and the increasing pressure caused some of it to solidify, blocking the escape of oxygen from the CF. LOX is inherently unstable in contact with organics, including carbon fibre, and can detonate under high temperatures, high pressures, shocks, etc; it has to be handled gingerly. In this case, the pressure continued to rise as the COPVs filled, until the LOX reached a critical pressure and detonated - thus rupturing the COPV reinforcement, thus the COPVs, thus the second stage and destroying the vehicle.

That's what it sounds like happened. But it'd be nice to get that confirmed or corrected if inaccurate. If this is correct, there's a number of things they could do to remedy it; I'd think the most likely would be to fill the COPVs before loading LOX.

As a side note, I'm really uncomfortable with their plan to make IPS entirely out of carbon fibre. As they're finding out (and has others have found out in the past), it's really difficult to use LOX with composites. And perhaps most importantly, inconsistently difficult. And the failure modes can be catastrophic - instant explosive rupture at the point of failure. Aluminum is not only light, but (by pure coincidence) one of the easiest things to work with LOX, as the oxide layer does a good job protecting the metal (even still, aluminum can detonate in contact with LOX in the right temperature/pressure/shock conditions, but said explosions are only self-propagating under significantly elevated pressure conditions). Also coincidentally, aluminum-lithium is even more resistant to reaction with LOX than lithium-free aluminum alloys. Basically, rocket manufacturers have been "having it easy" working with LOX by virtue of making rockets out of aluminum. You give that up when you go to composites.

But.... it's their rocket company, I guess we'll see how it goes.

Re:Would be nice...

[Bruce Perens]

We probably have ITAR to blame for not being able to read the full report. You can make all the FOIAs you want, ITAR is always going to be the excuse because all of the details of using a COPV successfully in a rocket is for the moment a trade-secret of a US company which the country doesn't want to hand over to North Korea, etc.

Besides it being their rocket company, they are making every effort to optimize delta-V over weight when nobody else in their market is trying. Otherwise, they would be using metal tanks and not attempting a high-risk technology like densification. You're going to blow up a few rockets if you take those risks.

Re:Would be nice...

[Rei]

LOX is unstable in contact with most organics. To the point that with the exception of some fluoropolymers, it's generally considered that all organics have a critical pressure in which they'll spontaneously combust with LOX. For many organics that pressure is below atmospheric pressure (aka hypergolic). For most plastics it is above atmospheric pressure, but not tremendously so. This includes the epoxy binders used in composites.

Yes, CF is the standard abbreviation for carbon fibre.

The LOX is supposed to be squeezed out of the CF as the COPVs pressurize. The COPV are comprised of a non-permeable aluminum inner liner and a permeable carbon fiber overwrap that bears the load. By freezing solid, the LOX was unable to escape the overwrap as the pressure increased as the COPVs were filled, and was correspondingly pressurized inside of it.

The system was not "designed so that it has areas which are likely to detonate". The LOX was supposed to be squeezed out of the overwrap, not become trapped in it as SOX.

None of their statements that I've come across mentioned "heating". They did, however, mention that the solidification of the LOX led to a pressure buildup. I've read quite a few LOX handing guidebooks (for working on a project involving LOX), and LOX pressurized against carbon fiber is considered an explosion hazard. You don't even store LOX in composite containers in low pressure conditions long-term. You know the main differences between a LOX dewar and a LN2 dewar? The latter often has either no lid and/or contains plastic or composite or silicone components. The former always has a lid and does not contain (non-fluorinated) plastic or composite components, and rarely silicone (fluoropolymers are usually okay). Also some metals don't work with LOX either.

It's not a case of "you say detonation, I say combustion". The spontaneous pressure-induced reaction of LOX and CF is a detonation. The rocket as a whole however was primarily consumed by a deflagration (non-supersonic combustion) between LOX and RP-1.

Nowehere in anything that I've seen from them were "sparks" mentioned.

Your "sparks" and "temperature" comments are directly in contradiction to SpaceX's comments about the conditions causing the formation of SOX and preventing the egress of LOX from the overwrap.

Re:Would be nice...

[Rei]

Indeed, and sometimes COPVs designed for other uses have various outer linings or coatings to protect the CF. But this comes with mass penalities. And rocket engineers are anything if not focused on not including any mass that they don't feel that they absolutely have to. And remember, SpaceX had no problem with their COPVs exploding prior to this one event; none of their testing had previously induced an explosion. So it's understandable that they'd have felt that it was fine. But LOX can be a harsh mistress. Not as unpredictable as, say, H2O2, mind you. But reading through past LOX incidents can be enlightening. For example, the Bell X1-D - it ultimately turned out to be that the gaskets had been treated with a softener, and that softener got into the LOX tank - and as soon as the tank started pressurizing, they hit LOX's critical pressure with the chemical and it detonated.

It's worth noting that the prototype ITS LOX tank that they made (also CF) is linerless. No coatings at all, just bare CF. Now, that's a different situation, it's not part of a helium COPV and thus not subject to the exact same failure scenario. But one doesn't have to wrack their brain too hard to come up with other failure scenarios related to transient impact, friction, general heat, bending or shock (all things that can set off LOX reactions). With aluminum, LOX reactions require fairly severe conditions, and generally self extinguish. With CF, that's not the case.

But perhaps I'm too much of a pessimist. I really want SpaceX to prove me wrong here and show that you can make safe, reliable LOX tanks out of CF :)

Re:Would be nice...

[Bruce Perens]

Of course, oxygen is neither "unstable" nor "explosive".

Every year or so, I stand on Pad 34 and someone tells the story of Apollo 1. I remember the day it happened, too. It's one every engineer should hear.

Re:Would be nice...

[deathguppie]

ya having worked for years with composites I can see your POV. Autoclaved CRP is inherently porous, The difficulties in sealing it for this kind of purpose is well known. Under low pressure loads you can depend on the secondary sealing material applied to it after baking but it does leave a lot of potential holes in the matrix.

Re: Would be nice...

[im_thatoneguy]

As a side note, I'm really uncomfortable with their plan to make IPS entirely out of carbon fibre. As they're finding out (and has others have found out in the past), it's really difficult to use LOX with composites.

Well for one thing the pressure in a COPV is several orders of magnitude higher than in a LOX tank so it seems foolish to over react to a failure of composites under extreme pressure and exotic conditioned when future applications will be different in nearly every way. Secondly, you could always work exactly the same as a COPV and line the interior of the composite structure with a thin layer of aluminum to prevent any contact at all. In fact we don't even know if that's not already the plan. In this instance SpaceX simply didn't think it was necessary to prevent contact of LOX and carbon and they were arguably right until they pushed the conditions slightly too far, it's telling that they are returning to flight with the exact same hardware.

You can't radically upset the economics of space flight by doing the exact same things the exact same way everybody else has always done it. You'll end up with the same thing at the same price.

Vandenberg weather horrible next Weekend

[TheSync]

Vandenberg AFB is forecast to have 50% chance of precipitation Saturday, 80% Sunday and 60% Monday.

Re:Musk's Deceipt

[Bruce Perens]

I do believe that the use of Russian engines dates from an ill-guided attempt to keep newly-unemployed Russian scientists and technicians from going into the WMD business. I find it difficult to accept that ULA, having charged the US Government $1 Billion per year just for a promise to stay in business, could not maintain a non-Russian engine capability.

There's also the issue of two competitors for Federal launch, Boeing and Lockheed, forming a Trust and not being blocked from doing so.

It's pretty clear they went hand in hand with legislators to ripping off the US taxpayer the way they did. This doesn't cause me to have more sympathy for them now.