NASA Will Take 2 Years to Complete Investigation into 2015 Falcon 9 Failure
Dragon capsule separated from Falcon 9 launch vehicle.
NASA’s investigation into the Falcon 9 launch failure that destroyed a Dragon cargo ship in June 2015 keeps getting more and more interesting.
I checked in again last week with the space agency about when it would be releasing a public report on the 18-month old accident. This is what a NASA spokesperson told me (emphasis mine):
NASA’s final report on the SpaceX CRS-7 mishap is still in work. While the report is important in providing NASA historical data of the mishap, the accident involved a version of the Falcon 9 rocket that is no longer in use. Furthermore, while the public summary itself may only be a few pages, the complete report is expected to exceed several hundred pages of highly detailed and technical information restricted by U.S. International Traffic in Arms Regulations and company-sensitive proprietary information. As a result, NASA anticipates its internal report and public summary will be finalized in the summer 2017.
That is a rather long time, even for a sometimes pokey government agency investigating the failure of a booster variant no longer in use.
It’s an especially long period given what SpaceX’s separate investigation concluded was the cause of the accident. According to a NASA Office of Inspector General (IG) report, SpaceX’s accident investigation into Falcon 9’s in-flight failure found the
most probable cause for the mishap was a strut assembly failure in the rocket’s second stage. Specifically, the failed strut assembly released a helium tank inside the liquid oxygen [LOX] tank, causing a breach in the oxygen tank’s dome and the release of gas that in turn disabled the avionics and caused release of the Dragon 1 capsule and break-up of the launch vehicle.
SpaceX completed an extensive analysis of the SPX-7 failure, consulted with NASA and the United States Air Force (USAF) regarding their analysis, and provided a mishap report and Return to Flight Plan to the FAA and NASA in November 2015. The company’s post-mishap testing of strut parts from the same purchase order as those used on SPX-7 found material flaws due to casting defects, “out of specification” materials, and improper heat treatment.
Elon Musk (Credit: SpaceX)
The solution sounded simple enough. Switch strut suppliers and test all the struts when they come in to weed out defective ones rather than relying on the contractor’s guarantee. At least that’s how SpaceX and founder Elon Musk described the fix, anyway.
SpaceX completed the investigation into the failure and was back flying the Falcon 9 only six months after the crash on Dec. 21, 2015. Three days earlier, NASA’s Launch Services Program (LSP) had briefed the space agency’s senior management on the results of its own separate investigation into the failure.
So, everything appears to have been largely wrapped up before Christmas 2015. So, why would it take another 18 months for NASA to complete its investigation and issue a public summary?
Yes, the version of the Falcon 9 that failed is no longer being flown, so perhaps there is no urgency. But, that was also true of the Antares booster that exploded just after launch in October 2014. Orbital ATK re-engineered the first stage with new engines after that accident. But, it only took a year for NASA to release a report on that accident.
The really intriguing question is: how could NASA’s investigation into the failure of a single defective strut produce a report with “hundred pages of highly detailed and technical information” restricted by export regulations?
That seems like overkill, doesn’t it? Unless, of course, the failure was more complicated than that.
No Probable Cause Found
Falcon 9 breaks up during a launch failure in June 2015
The NASA investigation delved deeper into SpaceX’s operations and reached a different set of conclusions. According to the NASA IG report [emphasis mine]
LSP did not identify a single probable cause for the launch failure, instead listing several “credible causes.” In addition to the material defects in the strut assembly SpaceX found during its testing, LSP pointed to manufacturing damage or improper installation of the assembly into the rocket as possible initiators of the failure. LSP also highlighted improper material selection and such practices as individuals standing on flight hardware during the assembly process, as possible contributing factors….
In February 2016, the NASA Administrator and the Associate Administrator for the Human Exploration and Operations Mission Directorate sent a letter to SpaceX expressing concerns about the company’s systems engineering and management practices, hardware installation and repair methods, and telemetry systems based on LSP’s review of the failure…
SpaceX has taken action to correct the deficiencies that led to the failed strut assembly and to address NASA’s concerns by conducting inspections, replacing suspect parts, and conducting additional testing. The company also reviewed the certifications of all spaceflight hardware and altered its quality control processes to better align with NASA technical standards. In order to track completion of its corrective actions, SpaceX is updating its process for identifying and resolving work-related tasks, which allows for improved auditing, prioritizing, and tracking of fracturable hardware.
The first paragraph of the above excerpt is almost the entire description of what NASA’s investigation found in terms of credible causes. The IG’s 54-page report was focused on how the space agency responded to the accident, not on what caused it.
As a result, the information raises more questions than it answers. For example, it’s not clear whether “improper material selection” refers to the struts or other parts of the booster around it.
Until NASA releases more definitive information next summer, we’ll have to rely largely on SpaceX’s finding that a single defective strut caused the accident. That conclusion was reached by an investigation board stacked with 11 SpaceX employee and a single FAA representative. The FAA official was the only board member not to sign the final report.
“We acknowledge SpaceX’s investigation was transparent and the observers from FAA, ISS, LSP, NTSB, and USAF had access to the investigation’s data and analysis,” the NASA IG report notes. “However, an investigation led by the employee responsible for the SPX-7 launch and run by the contractor responsible for the failure raises questions about inherent conflicts of interest.”
A Second Accident Raises More Questions
Credit: USLaunchReport.com
The question NASA’s investigation raises is whether a defective strut was the “root cause” of the failure. Did the strut alone cause the helium tank to break free? Or did something else cause the strut to fail other than the normal stresses of launch?
Stories have circulated within the space community for more than a year that it wasn’t the strut alone that caused the accident. The speculation was heightened after a Falcon 9 caught fire and exploded on the launch pad on Sept. 1 while it was being fueled for a pre-launch engine test.
The location of the fire and explosion this time? The second stage LOX tank again. And the problem? A large breach of a cryogenic helium tank inside of it.
Musk said the investigation pointed to the formation of solid oxygen during the loading of the helium tanks, which are covered with carbon composite materials. The oxygen then ignited the carbon composites, starting a fire that led to the explosion of the second stage.
The company has said it has reproduced the accident in tests “entirely through helium loading conditions. These conditions are mainly affected by the temperature and pressure of the helium being loaded.”
SpaceX hopes to return to flight next month using modified fueling procedures once the FAA grants the company a launch license. That decision will depend upon the results of the on-going accident investigation.
But, is simply changing the fueling process enough? Following the launch pad failure, SpaceNews consulted several experts who raised questions about the cause of the June 2015 accident. (Emphasis mine)
“The question is whether the strut was really the origin of the June 2015 failure. The struts were of below-specified quality, but it was not demonstrated that this was the root cause of the failure.
“It remains possible that a helium bottle burst in June 2015 and that, in parallel, the struts supporting it were of poor quality….
“But there is always the risk of correcting things that are not the real cause, such as correcting a badly built strut, which might not have prevented the June 2015 failure…”
If this theory is correct, then SpaceX has experienced two separate breaches of helium tanks in Falcon 9 second stages under very different conditions — in-flight and during fueling. It raises the possibility the booster has a basic design flaw that will not be fully addressed by procedural changes.
SpaceX denies any commonality between the two accidents. However, SpaceNews’ sources said that merely meant that the Sept. 1 failure was not caused by a broken strut but a tank breach.
Questions Swirl Around Composite Tanks
Despite SpaceX’s assurances, questions remain about the composition, location and durability of the helium tanks used in the Falcon 9.
SpaceX uses carbon over-wrapped pressure vessels (COPVs), which consist of a thin liner of aluminum covered with carbon composite fiber. The helium vessels are lighter and stronger than tanks made from aluminum or other metals, giving the Falcon 9 greater payload capacity.
The COPVs are placed inside the LOX tank, where they are soaked in extremely cold liquid oxygen. This arrangement is different from the ones used on many other rockets, where helium tanks are placed outside of the LOX tank.
Beginning last year, SpaceX began to densify Falcon 9’s propellants, a process under which they are chilled to an even lower temperature than they were for previous flights. The process reduces the volume of the LOX, allowing SpaceX to place more of it in the tank. The change helps to counteract the performance hit the Falcon 9 takes when the booster’s first stage is recovered.
The problem with submerging COPV’s in densified LOX is they can become brittle and develop cracks when exposed to the types of extremely low temperatures. (Emphasis mine)
Despite years of testing, concerns still exist about the potential for leaks, due to microcracking of traditional carbon/epoxy composite laminates at cryogenic temperatures. Microcracks can occur in any laminate because of the difference between the axial and transverse coefficients of thermal expansion (CTE) in each ply, explains Brian Wilson, president of Wilson Composite Technologies (Folsom, Calif.). “Transverse microcracks in the resin can be generated between the fibers as the laminate cools after cure, and as temperature is lowered to cryogenic levels.”
Even at moderate pressure, the composite’s exposure to temperature extremes and repeated fill-and-drain cycles causes thermo-mechanical loading, which exacerbates cracking and leads to permeation leak paths, easily traversed by small hydrogen and oxygen molecules. The issue isn’t helped by the fact that most thermoset systems lose strain capacity and become brittle at cryogenic temperatures.
Designing for containment of LOX poses particularly difficult problems. Any permeation leak poses a potent ignition-and-explosion hazard. There is unresolved debate in the industry as to whether LOX, an aggressive oxidizer, actually reacts with and degrades composite materials — some, including Wilson, say that a cured composite is not affected. Composites also have a tendency to pop, flash or char if impacted mechanically while in contact with LOX, because the mechanical energy of the blow causes a rise in heat within the material, which can, in turn, cause auto-ignition.
So, COPV’s are light and strong but vulnerable to failure, particularly when in contact with LOX. Thus, strict quality control measures must be observed during their production, installation and fueling to avoid. The question is whether those measures are enough to avoid additional bad days.
Commercial Crew Concerns
Dragon Version 2. (Credit: SpaceX)
NASA’s International Space Station Advisory Committee, led by Apollo veteran Tom Stafford, has raised the question of whether it is a safe practice to place the helium bottles inside the LOX tank instead of outside the tank.
Joseph Cuzzupoli, a former senior NASA manager who worked on the agency’s Apollo, Gemini and space shuttle programs, also expressed misgivings about SpaceX’s plans and the lack of NASA response. “Are we in the dark on this whole thing?” he asked.
Mr. Cuzzupoli told the committee that installing helium containers within fuel tanks—which entails putting wiring, sensors and tubing inside a potentially explosive environment—is “very unusual in my world, in my experience.” Such designs, he said “have been a no-no ever since Apollo.”
In 1970, a spark from an exposed wire inside an oxygen tank caused a life-threatening fire on board Apollo 13, bound for the moon. The crew managed a safe return to Earth, but NASA changed designs to prevent a similar incident.
This is a particular concern with the Crew Dragon spacecraft that SpaceX is building under NASA contract to take astronauts to the International Space Station. It’s also an issue for Dragon cargo ships and other NASA payloads the space agency has contracted SpaceX to launch.
The densified LOX has created a further concern for the committee. In order for the oxidizer to remain cold, it needs to be loaded just before launch. That means putting the crew on board the Dragon first and then fueling the booster.
“There is a unanimous, and strong, feeling by the committee that scheduling the crew to be on board the Dragon spacecraft prior to loading oxidizer into the rocket is contrary to booster safety criteria that has been in place for over 50 years, both in this country and internationally,” Stafford said in a Dec. 9, 2015 letter to William Gerstenmaier, NASA’s associate administrator for Human Exploration and Operations.
“Historically, neither the crew nor any other personnel have ever been allowed in or near the booster during fueling,” Stafford added. “Only after the booster is fully fueled and stabilized are the few essential people allowed near it.”
The advisory board is an outside group. However, these concerns are also shared by some within the space agency. It’s not clear how NASA and SpaceX are going to resolve these issues.
The Road Forward
One solution would be to simply not use densified propellants on the Crew Dragon flights. However, it is not clear what changes SpaceX might have to make in the booster to meet NASA’s requirements, or what they might cost to implement. For example, a second assembly might be required.
Not using densified propellants wouldn’t address the concern about having the COPVs inside the LOX tank. There are two possible solutions to this worry. One would be to replace the COPVs inside the LOX tank with ones made of metal. The second would be to move the helium vessels outside the tank.
SpaceX has not shown any indication of wanting to pursue any redesign of the second stage tank. Any redesign of the system would be costly and time consuming while adding complexity to the system. Additional failure modes would be introduced that would need to be tested.
Replacing carbon composite tanks with metal ones would add weight, resulting in lower payload capacity. Leaving them inside the LOX tank could still result in failures similar to the one Apollo 13 experienced.
The company might have to ground the Falcon 9 for an extended period of time. In all likelihood, NASA and the U.S. Air Force would need to re-certify the modified booster to carry government payloads, a costly and time consuming process.
SpaceX is already significantly behind schedule on flying its launch manifest due to a low flight rate and the two booster failures. The company has around 70 missions to fly in the years ahead, Some customers have grown impatient. Last week, Inmarsat moved a satellite from the perpetually delayed Falcon Heavy booster to Ariane 5.
There’s the potential for further delays to the Crew Dragon program, which is already years behind schedule due to a combination of under funding by Congress, technical challenges and bureaucratic delays at NASA. Major changes in the Falcon 9 could delay that program even further.
There’s also the question of SpaceX’s finances. With rock bottom prices, a low launch cadence, repeated failures, a head count exceeding 5,000 employees, and programs that include Crew Dragon, massive satellite constellations and human Mars missions, it’s not clear whether SpaceX is actually profitable. In fact, the company removed the claim that it was profitable and cash-flow positive from its own website.
If there’s another launch failure any time soon, SpaceX could be in serious trouble.
Sorting It All Out
SpaceX had ambitious plans for 2016. It was going to begin catching up on its manifest by launching 18 Falcon 9 boosters — triple the number of successful flights from each of the previous two years. After many years of struggling to launch regularly, this was going to be the breakthrough year.
As it turned out, the company managed eight successful flights before its ninth booster blew up on the launch pad during fueling. It was the type of on-pad accident that hadn’t happened to an American satellite launch provider in more than 50 years.
So, as 2016 comes to a close, SpaceX finds itself with the Falcon 9 grounded as it tries to complete its investigation into the accident. The company has questions swirling around about the reliability and safety of its launch vehicle that will need to be answered before the FAA grants a launch license or NASA puts crew on board it.
Meanwhile, NASA is increasingly dependent for cargo and crew services upon a company that has experienced two launch vehicle failures over the past 18 months, one without even leaving the ground. And SpaceX is asking the space agency to overturn a half century of safety practices in order to launch NASA’s most valuable assets.
One thing is clear: 2017 is going to be a very interesting year for Space X and NASA.
55 responses to “NASA Will Take 2 Years to Complete Investigation into 2015 Falcon 9 Failure”
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Hmm. If I were SpaceX, I’d be quietly (but somewhat furiously) working on a Plan B, specifically, a redesign in relation to those helium bottles.
I’d guess no one (not NASA, not SpaceX itself, not the ISS Advisory Committee, etc.) knows at this point if the rocket has a pretty fundamental design flaw, but it might, so having something close to ready just in case could end up saving the company’s bacon. Moving to a Raptor (which won’t use helium for pressurization of its tanks) powered EELV-class launcher could be ideal, but that’s only just starting subscale testing of the engine and tanks — such a launcher is years away.
No plan B is required. The accident report is already submitted to FAA along with the operational and hardware changes to mitigate the issue. Many cycles on the COPVs were tested at McGregor to bound the conditions where this issue was seen.
Getting to raptor will not help if the company is gone due to too many failures.
They have less failures than Ariane 5 for the number of flights. Is Arianespace gone? Boeing had 2 full and 1 partial failure of Delta III is row! Last time I checked they are still around. Where do you people come up with this stuff.
Both were backed by gov. Spacex is not.
You should check your facts.
THe Failures of the Delta III killed it as a commercial launcher.
Arianespace is clearly supported by ESA.
SX has NASA writing checks, if that continues they are good.
If that doesn’t, well, I hope they are able to sustain.
That’s my point — they should have a redesign of the pressurization system for the Falcon 9 in the works as the Raptor, which will use a different pressurization system for its tanks, is too far away. They may need something to bridge the gap, or, with another failure, they might find themselves unable to continue (out of business).
The other alternative is, of course, to manage the risks of the current design through things such as minor design changes to beef up possible weak links, procedures changes, increased monitoring and strict controls. That’s essentially what the shuttle program did — after the Challenger disaster they beefed up the SRB joint that failed and they modified procedures not to launch after subfreezing temperatures; and after Columbia they had on orbit inspections of the heat shield, a safe haven at the ISS and another launcher almost ready to go if a rescue was needed. In a sense, they muddled through with a problematic design and made things work for many many years before a new generation would be ready to come on line (for which we’re still kinda waiting).
SpaceX may similarly muddle through until a Raptor-powered rocket is ready years from now, but as that is so far away, I’m recommending they have a redesigned pressurization system in the works in case the current system proves inherently unacceptably risky.
Isn’t every design operated through managing the risks? I bet if you load the COPVs on an AtlasV out of spec (too high a pressure / past the proofing point) bad things will happen. In the case of Atlas they are sitting in the intertank region between the forward/aft bulkheads of the propellant tanks. What do you think happens if one of them lets go? More to the point isn’t it most probable that the AMOS failure was the lack of managing an unknown risk rather than a fundamental design flaw?
Also would like to know what is encompassed by this re-design you are recommending? Moving COPVs? If so where? Changing them to metal? They would probably need to be spherical. F9 cores aren’t particularly wide do you know how spherical tanks will impact stratification of the LOX? If you make the tanks smaller, but more of them, did you look at the mass penalty of not just the tanks but the plumbing; accounting for extra risk of having more plumbing/manifold in the tank. Did you account for Titanium Oxide reaction is exothermic and would need to be handled if you go with Ti spheres. And the list goes on. No free lunch.
No, I don’t know — I’m not recommending a particular redesign, I’m recommending they get to work on a redesign in case it has to be implemented. A plan B. The particular redesign I’ll leave to the engineers involved. Also, of course everything has tradeoffs!
Dang, dude. If you were running a business and ran into a problematic area (we’re talking explosions and complete failure of your main service [deliver a customer’s property to a destination], loss of customers’ property, and repeated loss of almost all revenue for months-long periods), would you implement a policy of refusing to even look at having a modification in the works because a modification would be hard and “there’s no free lunch”? Seriously.
They *are* modifying the hardware and procedure to avoid the issue. That isn’t the point. My point is they cannot move the COPVs elsewhere, because there is no place to move them to. Once you put them outside the tank you need to remove the common bulkhead. Once you remove the common bullhead you’ve increased mass and reduced propellant volume. The stage can’t be made any longer or wider. The top of the LOX dome is covered in PAF and avionics gear. You basically have a new rocket at that point (well over a year of work, and performance that blows out reuse capability or even probably some expendable missions they can do now without some help with solids. SpaceX would be gone anyway if they just tried to build a different form of Atlas V. The only other choice is to move to metal spheres which is a huge change that significantly reduces the the PMF while introducing a whole new set of unknowns into the design that simply isn’t necessary. In essence SpaceX needs to make COPVs work or they are out of business anyway. And no reason to believe they can’t as they need to cover the conditions that let to the failure on AMOS. They’ve flown hundreds of these COPVs without blowing up. Logic stands they simply need to manage the variables in play for AMOS to prevent that issue. Rockets have blown up before without COPVs. Saturn V upper stand blew up on the test stand when metal helium tank (outside cryogenic conditions) split in half. No free lunch, like I said.
can they move Helium bottles to the Boat tail and the area between the first and second stage?
Unlike Centaur/RL10 the Merlin is a pretty large upper stage engine in relation to the relatively small diameter core. The tanks would have to be larger than they are now for equal storage as well. I don’t see where these go.
Are you suggesting they keep tanks submerged on S1 too? Is there is room back there with 9 engines/bays and associated octopus plumbing? Remember you don’t really get to stretch/widen anything here.
That CRS contract is a little rough there buddy. It’ll take 2 years to negotiate a contract with Roscosmos to get U.S. crew their supply end of the bargain. ISS will have to rely on Cygnus and Dragon,
Great article.
You’re raising good questions.
SpaceX’s president said awhile back that the company was 99% certain that a bum strut had caused the 2015 failure She also said she was pretty sure nasa and the air force agreed with this, though it seems they didn’t.
As you say, SpaceX’s reason for not relating the 2015 and 2016 failures seems down to their having ruled out the helium tank in the 2015 disaster.
But what if they got it wrong in their 2015 rundown? SpaceX may not want to reopen this can of worms, but it looks like nasa’s never closed it.
This clearest reason for this long nasa investigation would be that they suspect SpaceX diagnosed the wrong illness. Because if SpaceX got it wrong in 2015, then a single bug may have taken out both rockets, and may still be in hiding out, waiting to take down even more.
I keep imagining that many years from now, a graying wrinkled Elon Musk will confidently assert to all who will listen that SpaceX will ‘certainly’ establish a space colony on Mars before the beginning of the 22nd Century.
Musk doesn’t even assert that now. What are you smoking?
Actually, NASA and the Air Force seem to agree that a broken strut caused the 2015 failure. The “several “credible causes”” mentioned in the article are “in addition to the material defects in the strut assembly SpaceX found”
I’m glad NASA’s investigation is still open. There are enough unknowns and similarities in the location of the failure origin that it remains plausible they are connected.
Even if not it seems SpaceX is admitting to having poor sourcing and quality control practices in place if it was the struts.
Not really. The original strut company was well known for making them. They do it for others. If so, I would not be surprised that they were not checking. Sadly, far too many companies are getting greedy and cutting corners.
What I meant is they admit they didn’t do a good job checking if the parts they ordered met all their requirements (which may or may not be the same as the supplier’s requirements since not everyone is building rockets). Wasn’t a comment on the supplier being shoddy.
LOX and Carbon Composites are certainly a (very) tricky combination (as demonstrated at least by the Falcon9/AMOS-6 launch pad failure), but the benefits of the lighter CC structures are just too good to ignore, so many companies are pursuing this road. SpaceX itself will have all CC LOX (and fuel) tanks for ITS, and even long before that, Rocketlab will start flying its all CC Electron rocket early next year (hopefully).
So I guess we will learn pretty soon if CC LOX tanks are manageable in the real world, or just a theoretical dream.
I think we will find it is very manageable. The same way everything we have today is manageable because of lots of explosions in the 50-60 even 90s. People take SRBs as “reliable” why after numerous Shuttle, Titan, Delta failures? Because the risk is managed with among other things inspections and understanding the bounds of the designs.
I hope you are right.
Not only was it a good and needed write-up, his last sentence says it all. Spacex really has to get things right by paying attention to the ball.
Another mishap, and the insurance may eat up the savings that spacex gives.
There was basically nothing technically new in this article that hasn’t been said already other than the information in the title.
huh.
Doug puts in a lot of work on this, and ppl like you have nothing but carping.
Have you considered trolling elsewhwere?
Simply pointing out the truth is trolling? Doug didn’t even argue that point.
There’s nothing new here. I don’t see the relevance of that complaint. Has nothing to do with the quality of this piece, which I’m quite proud of.
If all you got out of this story is that NASA is slow at producing reports, then you didn’t understand it.
<rant>I read articles mostly for new facts “information” to drive my decision making. No offense but I am not terribly interested in yours. Partially because you’ve already done a quite eloquent job in conveying this over several articles and comments covering the same ground, I get it, I don’t need to read the nth article to find out your position.
You rampantly misuse the term “root cause” when the technical failure would be proximate cause, whatever it turns out to be. Musk said, in the CRS-7 preliminary finding call, they were looking at a material change in the struts. That means SpaceX selected the wrong material the first time around. They don’t get a mulligan on material selection without the first swing being wrong/marginal. Whether there was the data pointed to other material selection problems is irreverent as they needed to resolve all of them to fly again.
The NASA Mission Assurance manager for Jason 3 is on record (I saw the video Jan 2016) saying that they were flying a clean vehicle and were 100% satisfied that all outstanding issues were resolved satisfactory w.r.t CRS-7 or any other issue impacting F9 v1.1. So either he was a lying/incompetent MA manager or SpaceX adequately resolved the issues the data pointed to. You can’t have it both ways, if there was solid data pointing to linkage to AMOS-6 type failure (or away from strut/strut attachment), which there apparently wasn’t, then NASA was negligent to let Jason or subsequent CRS missions fly on F9. If the stated fix for CRS-7 failure, strut failure at the attach point, was incomplete per NASA the same applies.
On the other hand, all I get here is backhanded innuendo trying to slide both failures into the same bucket all the while stating there is no data to suggest that should be the case. This wrapped in expert testimony on examples of why high performance rocket engineering is complicated. Using “experts” that aren’t on the ground, knowledgeable of the detailed design and testing/verification of a complex systems, is generally just about dangerous enough to describe the “possible issues” that everyone knows about, but not the one that counts. SpaceX has many cycles of submerging He COPVs in LOX between S1/S2 under it’s belt. If there were micro-cracking of the COPVs this would be seen through various operating cycles, not the least of which on landed booster stages under similar loading conditions up to 10 times now. If there was a variance in the fabrication this would also have shown up in subsequent testing of bottles on the ground in the same batch and/or records during manufacturing.
An example of this would be turbopump stress fractures observed earlier in the year that delayed SES until they could get a better understanding of them. Seems clear there is a corner case they ran into on AMOS that took out one COPV bottle (out of hundreds flown and hundreds more loading/validation events on the ground), SpaceX’s fault for sure, but just throwing your hands up with “questions swirling” is intellectual vaporware. </rant>
“Seems clear there is a corner case they ran into on AMOS that took out one COPV bottle (out of hundreds flown and hundreds more loading/validation events on the ground),”
If you have something that has a 1/Hundred failure with 1/Hundreds loadings, but you have 12 bottles per bird and say 4 loading events per mission and 9 missions per year,
you now have 432 loading events/year and 108 bottles flown/year… That starts to raise the odds of an event happening into odds of one every year or so….
The trick in aerospace is that even if things seem to be rare, you have to master the statistics of russian roulette.
Say the odds of something happening are 1:10,000 but you have 600 of these widgets on board and you fly 8 times per year, how many times are you spinning the cylinder and clicking off?
If the odds are like this, what’s the money worth to spend to reduce that odds of 1:10,000 to 1:100,000?
I’m not suggesting they do nothing. I’m suggesting whatever they hit can be avoided. You’ve missed the point here.
Edit: including missing *not*
It’s putting all the pieces together that tells the story!
Wonderful job Doug!
I fail to see what is new in this article that was not known already other than NASA takes too long to write up a report. Clearly there isn’t going to be any “new” data coming out about CRS-7 in the next 6 months so the delay is simply just resource allocation.
You want something new? Working on exactly that. Just not quite ready for prime time.
You’re not going to be very happy with it, but that seems par for the course. Not much I can do about that.
Waiting with bated breath…
That sounds disgusting. Use some mouthwash.
I read that the main reason for super-chilled propellent is so that the F9 could serve as a routine GSO launcher, even though it is a medium-lift vehicle. FH should allow F9 to stay out of the GSO market and go back to non-super-chilling. However, this business of the laminate cracking does not sound like a good thing for a reusable booster. I realise that the accidents were in the second stage, but this seems on the surface like it could cause a reused first-stage to fail.
F9 does not do GSO missions just GTO. To do useful GSO mission would require either FH+Raptor based upper stage or additional thermal control/batteries for the long duration cold soak for GSO missions. All medium lift (by EELV standards) do routine GTO missions like F9.
The reason F9 does the sub-cooled LOX is three-fold:
1) They want extra margin for returning first stage on GTO mission profiles (reuse is a major reason for SpaceX existing in the first place)
2) They are limited in size of the booster/second stage diameter/length because of road transportability and bending moments (fineness ratio). Notice Blue Origin is also going to do re-use but without sub-cooling as they have an LNG/LOX system built close to the Cape so no transport limits on core diameter.
3) F9 is among other things a technology demonstrator for ITS which requires sub-cooling to get the huge performance (basically SSTO for the tanker spacecraft portion) along with carbon fiber to close the numbers on that kind of throw toward Mars along with reuse.
SpaceX is planning to stop numerous improvements after Falcon9 Block 5 release in 2017. It will be enough for the most of GTO SATs and have to be reusable up to 10 times.
How many times has SX re-used a booster so far?
Zero. They have returned five boosters but haven’t flown any of them again.
So, the actual “savings” of reuse has yet to be realized…interesting…
the hope is of course high, but, the learning curve remains steep. I’m not surprised SX is studying the birds, the real question is when will they be satisfied they have learned the lessons and moved them into design and production.
I think we are going to find out the redesign of the COPV location will make these birds obsolete. Just a guess…:)
Thanks.
Just ignore Snarknado. I do. Very little I write seems to ever please him. He’s like the movies. Enjoyable at first, then gradually declines. On Rotten Tomatoes the films went from 82 percent to 61 then 36 and all the way down to 18.
Yes, but for those inspections to yield a clean vehicle, NASA must agree they are inspecting the correct bits and the analysis that drove the special inspections was sound.
SpaceX maintained that when the Falcon 9 was designed and developed it was done according to all of NASA’s published data for human spaceflight. They also stated they had NASA looking over their shoulder and were basically given the green light for the design. I never once heard or read anything from NASA that they had trouble with the submerged helium tanks. I do not recall in the last decade every seeing that issue reported. Did NASA have a problem with the submerged tanks from day 1 ?
Maybe it shows that the current crop of “rocket scientists” at NASA are just as incompetent as those at SpaceX.
There’s no evidence that either are incompetent.
Very good article.
What about that drone, boys? Or am I the only one with a lick of sense on the internet. Wasn’t a freakin’ insect.
It was a freaking insect.
Not a drone, no way one could have approached an Air Force base.
It could have been a bird.