SpaceX focusing on helium system in Falcon 9 test anomaly
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.”
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.”
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.