Falcon 9 explosion narrowed to helium system failure
Faster than the blink of an eye – that’s how little time there was between the first sign of an anomaly and the loss of the Falcon 9 rocket with the AMOS-6 satellite during a pre-flight test propellant loading operation on Sept. 1, 2016. After poring over the data, SpaceX engineers have narrowed down the likely cause of the explosion to a failure in the upper stage’s helium system.
Largely silent in the days following the incident, SpaceX has provided scant information on the progress of the investigation – until now. In a release issued by the company Sept. 23, 2016, SpaceX outlined some of the findings of the Accident Investigation Team (AIT) – composed of SpaceX, the Federal Aviation Administration, NASA, the U.S. Air Force, and industry experts – and on the condition of the infrastructure at Launch Complex 40 (LC-40).
Although SpaceX was recording approximately 3,000 channels of data during the operation, there was very little notice of the impending failure. According to the release, “The timeline of the event is extremely short – from first signs of an anomaly to loss of data is about 93 milliseconds or less than 1/10th of a second.”
Not restricted to just the data recorded during the incident, investigators have also been reviewing video, audio, and imagery evidence. Additionally, investigative teams have recovered and cataloged the majority of the debris from the incident. Early indications point to a failure of the pressurization system in the vehicle’s second stage:
At this stage of the investigation, preliminary review of the data and debris suggests that a large breach in the cryogenic helium system of the second stage liquid oxygen tank took place. All plausible causes are being tracked in an extensive fault tree and carefully investigated. Through the fault tree and data review process, we have exonerated any connection with last year’s CRS-7 mishap.
Though the pad itself sustained significant damage, the area surrounding LC-40 seems to have fared relatively well:
The teams have continued inspections of LC-40 and the surrounding facilities. 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 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.
The company also reported work continues at the LC-39A facility – a former Space Shuttle launch pad – located several miles from LC-40, with a focus on preparing it for operation sometime in November. SpaceX entered into a 20-year lease for the historic launch site in April of 2014.
Furthermore, SpaceX indicated production at their Hawthorne, California, facilities will resume on systems and components as they are “…exonerated from the investigation.”
SpaceX anticipates a return to flight as early as November 2016, pending the investigation’s results.
Curt Godwin has been a fan of space exploration for as long as he can remember, keeping his eyes to the skies from an early age. Initially majoring in Nuclear Engineering, Curt later decided that computers would be a more interesting - and safer - career field. He's worked in education technology for more than 20 years, and has been published in industry and peer journals, and is a respected authority on wireless network engineering. Throughout this period of his life, he maintained his love for all things space and has written about his experiences at a variety of NASA events, both on his personal blog and as a freelance media representative.