(Bloomberg) -- SpaceX’s billionaire founder Elon Musk called the Falcon 9 explosion its most perplexing failure in 14 years, deepening the mystery surrounding the loss of the satellite-bearing rocket on its launchpad last week.
U.S. investigators are looking into why the Falcon 9 rocket, developed by Musk’s Space Exploration Technologies Corp., blew up on Sept. 1 before a scheduled test launch in Cape Canaveral, Florida. The explosion incinerated a satellite that Facebook Inc. had planned to use to beam Internet access across parts of Africa, and set launches back across the world.
Musk, chief executive officer of SpaceX and Tesla Motors Inc., wrote in a tweet Friday that the rocket’s engines weren’t on at the time of the explosion. Musk also asked for any recordings of the event to be e-mailed to the Hawthorne, California-based rocket maker.
“Still working on the Falcon fireball investigation. Turning out to be the most difficult and complex failure we have ever had in 14 years,” Musk tweeted on his verified Twitter account. “Important to note that this happened during a routine filling operation. Engines were not on and there was no apparent heat source.”
About 20 people from SpaceX, the Federal Aviation Administration, the National Aeronautics and Space Administration, the U.S. Air Force and around the industry are part of a core investigative team that’s evaluating data to determine the cause of the anomaly, according to a person familiar with the investigation. Hans Koenigsmann, SpaceX’s vice president of flight reliability, is leading the probe on behalf of the company.
The group will be conducting a thorough “fault tree analysis” to try to determine what went wrong. It’s unlikely that SpaceX will return to flight until the investigators reach a consensus, said the the person, who asked not to be named due to the continuing investigation. Commercial spacecraft operators have to apply for a license from the FAA in order to fly, while range approval is subject to approval by the Air Force. SpaceX has NASA contracts to ferry cargo as well as astronauts to the International Space Station.
The FAA is limited to an advisory role, the agency said. “Per the launch license and FAA regulations, SpaceX will conduct the investigation with oversight from the FAA,” it said in an e-mail.
The spacecraft had been filled with a common rocket fuel that explodes when mixed with liquid oxygen, and while there are many potential scenarios, a spark, static discharge, or metal on metal collision may have been enough to set off that mixture in case the oxygen tank ruptured, said Josh Barker of the National Space Centre in Leicester, England. Explosions on the launch pad are more uncommon than accidents after a launch occurred, because with engines off staff have more control over the process, he said.
“SpaceX have been very reserved around information being given out. As a commercial company this is no doubt to manage their reputation as best they can,” Barker said. “They will remain fairly tight lipped until they know exactly what caused the issue. The request for more footage and assistance that Musk has called for shows that this investigation could still have a long way to go.”
Focus on Milliseconds
The accident led to SpaceX’s second loss of a spacecraft in little more than a year, and occurred eight minutes before a scheduled test firing during a dress rehearsal. SpaceX, which was founded 14 years ago in 2002, said it began searching for the root cause of the accident immediately after the loss, reviewing about 3,000 channels of telemetry and video data covering 35 to 55 milliseconds.
“Particularly trying to understand the quieter bang sound a few seconds before the fireball goes off. May come from rocket or something else,” Musk tweeted. Asked on Twitter whether it was possible that a foreign object had struck the rocket, Musk replied: “We have not ruled that out.”
Data showed the anomaly started around the upper stage liquid oxygen tank, the company said. The blast was a reminder of the peril inherent in space flight, which relies on controlled explosions to power payloads into orbit.
After a Twitter user suggested that a noise sounded like a metal joint popping under stress, perhaps a “weld failing on a strut” or seam bursting, Musk responded, “Most likely true, but we can’t yet find it on any vehicle sensors.” Last year, a SpaceX rocket blew apart about 2 minutes after launch because of a two-foot-long, inch-thick strut in a liquid oxygen tank that snapped.
Prolonged investigations “could prove problematic for SpaceX as they rely on customers using their rockets to launch satellites,” Barker of the National Space Centre said. “Accidents such as these can put operations on hold for up to 12 months.”