The explosion that destroyed SpaceX’s Falcon 9 rocket earlier this month was probably caused by a large breach in its upper-stage helium system, the company said in an anomaly update published Friday. SpaceX also clarified that the mishap had no relation to last year's accident, when a rocket — also a Falcon 9 — exploded two minutes after liftoff.
"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,” SpaceX said in the update. “Through the fault tree and data review process, we have exonerated any connection with last year’s CRS-7 mishap.”
Last year’s Falcon 9 accident was caused by a faulty steel strut that was supposed to hold down a tank of high-pressure helium.
The investigation into this month’s accident is far from over. A team composed of officials from SpaceX, NASA, U.S. Air Force and the Federal Aviation Administration is still poring over 3,000 channels of telemetry and engineering data to pinpoint the exact cause of the breach.
“All plausible causes are being tracked in an extensive fault tree and carefully investigated,” SpaceX said. “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.”
The company also addressed worries that the incident could delay its other launches planned for later this year, acknowledging that the fire had damaged “substantial areas” of LC-40 — SpaceX’s primary launch site in Cape Canaveral, Florida.
"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," the company said. "SpaceX’s other facilities, from the Payload Processing Facility at the Cape, to the pad and hangar at LC-39A, are located several miles from LC-40 and were unaffected as well."
Over the past two years, SpaceX has been actively testing its flagship Falcon 9 rockets equipped with technology that allows them to be recovered and reused. So far, the company has succeeded in landing the lower stages of six of its Falcon 9 rockets, including four that have been landed on drone barges at sea.
Just two days prior to the Sept. 1 explosion, SpaceX signed its first customer for a previously used Falcon 9 rocket — the Luxembourg-based satellite operator SES, which is scheduled to launch its SES-10 satellite later this year. In total, SpaceX currently has 70 missions in its manifest — estimated to be worth over $10 billion.
“We will work to resume our manifest as quickly as responsible once the cause of the anomaly has been identified by the Accident Investigation Team. Pending the results of the investigation, we anticipate returning to flight as early as the November timeframe,” the company said.