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SpaceX’s Falcon 9 explosion likely caused by breached helium system

SpaceX’s Falcon 9 explosion likely caused by breached helium system

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SpaceX’s recent Falcon 9 explosion seems to have been caused by a breach in the "cryogenic helium system" of the vehicle's upper oxygen tank, according to an update from the company. However, SpaceX says the accident is not connected to last year's Falcon 9 explosion, when a rocket disintegrated en route to the International Space Station.

The accident is not connected to last year's Falcon 9 explosion, according to SpaceX

On September 1st, one of SpaceX’s Falcon 9 rockets exploded on a launch pad at Cape Canaveral, Florida as the vehicle was being fueled in preparation for a static fire test. The test involves turning on the rocket's engines while the vehicle is constrained. The static fire was supposed to determine if the Falcon 9 was ready for its upcoming launch of the Israeli communications satellite, Amos-6, but both the rocket and the satellite were destroyed in the explosion before the test even occurred.

Though SpaceX is narrowing down the possible sources of the explosion, it still has yet to determine what caused the breach in the helium system. "All plausible causes are being tracked in an extensive fault tree and carefully investigated," SpaceX said in a statement. The company's Accident Investigation Team is still conducting its investigation, which involves analyzing 3,000 channels of data, according to SpaceX. The team is also looking at video and audio recordings of the event. But despite all this information, the team is reviewing an accident timeline that boils down to just 93 milliseconds.

While this most recent explosion is not connected to what brought down SpaceX's Falcon 9 in 2015, the problems for both failures originated in the vehicles' upper liquid oxygen tanks. And both involved the vehicle's helium system in some way. However, the Falcon 9 failure last year was caused by a faulty strut in the liquid oxygen tank, used to hold down one of the helium pressure vessels. These vessels help to pressurize the rocket.

"Substantial areas of the pad" were damaged

SpaceX also gave an update about the state of its launch pad at Launch Complex 40, where the explosion occurred. Apparently "substantial areas of the pad" were damaged, but control systems for the pad are in good condition and the nearby Falcon Support Building — an office building at the pad — wasn't affected. Other important hardware at LC40 are also mostly okay, too, including the tanks that store the super-chilled oxygen for the rockets and the tanks that hold the kerosene fuel.

Meanwhile, SpaceX says it's working to get back to spaceflight as soon as possible, still targeting to launch again in November. The company has the option of launching from two other launch pads: one at Vandenberg Air Force Base in California, and another launch pad at Launch Complex 39A in Cape Canaveral, which will be ready to support Falcon 9 flights in November.

Additionally, the company is still working on getting its vehicles ready for NASA's Commercial Crew Program, in which SpaceX is supposed to start transporting astronauts to and from the International Space Station in the next couple of years. The company hinted that figuring out the source of the September explosion will make the Commercial Crew Program more robust. "Getting back to flight safely and reliably is our top priority, and the data gathered from the present investigation will result in an even safer and more reliable vehicle for our customers and partners," said SpaceX.

Correction: A previous version of this article described the Falcon Support Building as a hangar. It's an office building near the pad, and the article has been updated.

SpaceX made history with the Falcon 9 in April