Failed Strut Responsible for Explosion of Falcon 9 Rocket, says Elon Musk

Today, founder Elon Musk said the SpaceX rocket explosion on June 28 was caused by a faulty strut, destroying over a 4,000-pound cargo, which was bound for the ISS or global Space Station.

The struts are created to handle 10,000 pounds of force at liftoff; at the time of the accident, they would have been seeing only 2,000 pounds of force.

“This is the best of what we know thus far,” Musk said. The helium then leaked into the oxygen tank (it sits inside that tank) and caused “an overpressure event”, Musk said.

Musk emphasized that this conclusion is preliminary, and highlighted more research is ongoing to confirm the cause with confidence.

It was not immediately obvious the strut was the hardware that had failed, based on flight experience and ground testing, resulting in data on hundreds of struts – including those that had already flown without issue. The helium tanks themselves are held in place by struts, and it’s one of these internal struts that’s believed to have failed. Musk declined to provide the name of the supplier.

Exactly why the strut failed – and in doing so caused a breach in the helium system which, naturally, exploded – seems unclear. (Dragon cargo capsules make parachute-aided ocean splashdowns after completing their missions.) [The Rockets and Spaceships of SpaceX (Photos)]. If the Dragon had been equipped with different software, the capsule what have been able to deploy its parachutes and save its contents.

He went on to say that even if it had been a Crew Dragon carrying astronauts, the passengers would have survived, so the CRS-7 accident will not delay SpaceX’s plans to ferry crews to the ISS or alter future launch dates.

Rocketry, he noted, is an activity where a “passing score is 100% every time”, and he volunteered that this failure, which followed a run of 20 successes over seven years, is a sign of “a company as a whole that has become a little complacent”.

The Falcon 9’s Dragon payload capsule survived the initial explosion and was still transmitting telemetry, right up to the point when it vanished over the horizon and smashed into the Atlantic shortly thereafter.

In his first public comments on the disaster, Musk said the strut “would appear to be incorrectly made, but with no visible way of determining that from the outside”.

This is a huge setback for SpaceX, but Musk asserts that the company is on it and working to fix it for future launches. Tesla CEO said the part received authorization from a third-party that it would stand the stress of a rocket lift off.

He also said the problem is not expected to delay the company’s goal of sending astronauts to space aboard its Dragon spaceship within the next two years.

NASA is allowing SpaceX to do its own investigation into the failure.

Beyond the cost of the $60 million rocket and four tons of supplies, the Falcon 9 is the company’s work-horse product.

In the video, you can see that what happened was not technically an explosion; there’s no fireball, but you can see the expanding vapor from the oxygen tank flying away.

“It’s a really odd failure mode”, Musk told reporters on a conference call.

Musk said it had not yet been decided which mission will be first in line when Falcon 9 returns to flight.