Spaceflight Insider

SpaceX focusing on helium system in Falcon 9 test anomaly

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Image Credit: Mike Wagner / US Launch Report

SpaceX recently announced that the Accident Investigation Team (AIT), composed of SpaceX, the Federal Aviation Administration, NASA, and the U.S. Air Force, had narrowed the source of the Sept. 1, 2016, anomaly that destroyed a Falcon 9 rocket and its satellite payload prior to a ground propulsion test. While the NewSpace company has not yet identified the actual cause of the anomaly, the accident itself appears to have originated in the second stage cryogenic helium system.

A very fast fire

“All plausible causes are being tracked in an extensive fault tree and carefully investigated,” the Sept. 23 SpaceX update stated. “Through the fault tree and data review process, we have exonerated any connection with last year’s CRS-7 mishap.”


SpaceX uses composite overwrapped pressure vessels (COPVs) similar to these in order to store helium aboard the Falcon 9. Photo Credit: ESA

According to the Wall Street Journal, at a press conference at the 67th International Astronautical Congress in Guadalajara, Mexico, SpaceX CEO Elon Musk said the AIT “have eliminated all of the […] obvious possibilities.”

SpaceX stated in an update that preliminary review of the data suggests a large breach in the cryogenic helium system of the upper stage took place.

The cryogenic helium system is used to pressurize the upper stage prior to ignition by injecting helium into the tank and forcing the propellant down toward the engine.

The explosion, which Musk has preferred to call a “fast fire”, erupted quickly. The first indication of a problem occurred only 93 milliseconds – less than a tenth of a second – before SpaceX lost data. Additionally, on Twitter, Musk stated the AIT was “trying to understand the quieter bang sound a few seconds before the fireball goes off. May come from rocket or something else.”

The AIT is going over approximately 3,000 channels of engineering data along with video, audio, and imagery. In a tweet, SpaceX also invited members of the public to share any imagery of the incident to help with the investigation.

SpaceX reports that most of the debris “has been recovered, photographed, labeled and catalogued, and is now in a hangar for inspection and use during the investigation.”

Other updates

In addition to clearing and cataloging the debris, SpaceX has been reviewing the condition of Space Launch Complex 40, which has been the company’s primary launch site at Cape Canaveral Air Force Station since 2010.

“While substantial areas of the pad systems were affected, the Falcon Support Building adjacent to the pad was unaffected, and per standard procedure was unoccupied at the time of the anomaly,” the Sept. 23 update stated. “The new liquid oxygen farm – e.g. the tanks and plumbing that hold our super-chilled liquid oxygen – was unaffected and remains in good working order. The RP-1 (kerosene) fuel farm was also largely unaffected. The pad’s control systems are also in relatively good condition.”

In addition to pursuing the accident investigation and its launch pad development efforts, Musk is also looking at the more distant future. On Sept. 27, he announced the development of the Interplanetary Transport System.

However, before all of those plans can come to fruition, SpaceX will have to determine the cause of the Sept. 1 anomaly. In a Sept. 9 tweet, Musk admitted that the investigation is “Turning out to be the most difficult and complex failure we have ever had in 14 years.”



Bart Leahy is a freelance technical writer living in Orlando, Florida. Leahy's diverse career has included work for The Walt Disney Company, NASA, the Department of Defense, Nissan, a number of commercial space companies, small businesses, nonprofits, as well as the Science Cheerleaders.

Reader Comments

Wasn’t something very similar to this that destroyed the vehicle in the CRS-7 mission?

Richard Alexander

SpaceX ruled out the same cause as the CRS-7 mission, which had been ruled as a failed brace.

The early “bang” heard could have been the Helium tank rupture? Was the tank constructed in house by SpaceX or an outside contractor?

I believe these are in house for SpaceX

The integrity of a copv is highly dependent on careful control of the composite over wrap process, because an explosion can result from a piece of carbon fiber breaking off in liquid oxygen.

It seems that Spacex needs a complete redesign of their Helium system, and to think that soon America will entrust their most precious cargo, American Astronauts to a rocket that has two explosions in 15 months will bring another national disaster, I see another Challenge in the future of our space travel, but at least they are cheap!

I don’t think they’re helium systems need a complete redesign but there seems to be an issue somewhere. Making composite materials able to withstand the temperature stresses of cryo is pushing the limits of current tech but is vital to reducing weight. Other rocket companies don’t even cryo freeze their LOX because of the challenges it presents. I think Spacex is going to be a poineer of composites in the future as it needs the tech to improve for its falcon 9 as well as the fully carbon fiber interplanetary rocket it just revealed. Elon loves scaling up but he needs to be careful, he’s always pushing the envelope.

I think SpaceX may be the first company to be putting COPVs inside the LOX tank. There was reference to similar on I think the Saturn V, but those may have been all metal, not composite-wrapped. Composites are notoriously (low) temperature sensitive, I’m pretty sure.

I think if I was them, I’d be instrumenting one, bracketing it inside a dewar, flight pressing it and submerging it in the supercooled LOX to watch what happens.

The voice of reason

“Other rocket companies don’t even cryo freeze their LOX”

What exactly do you think other companies do with their Liquid Oxygen if they don’t “cryo freeze” it (whatever that means)?

I wonder if anyone is considering a 50 Cal sniper round? There are plenty of companies and nations who benefit from this…

SpaceX itself has stated it was a problem with the Falcon 9’s helium system. We are uncertain therefore why you’re posting bizarre conspiracy theories. However, this is dangerously close to violating our commenting policy (we don’t allow lying on our commenting threads).
Jason Rhian – Editor, SpaceFlight Insider

Spacex is a failure company with few real engineers and too many loud mouth former laxidazical ceos. It can’t compete with NASA.

Atlas V, Delta IV, Delta II, and Vega rockets plus many, many satellites use pressurant tanks and propellant tanks made by Orbital ATK at a facility just a few miles from SpaceX HQ. They are extremely reliable and DO NOT fail. SpaceX, please give them a call, might save your rocket business.

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