Faulty strut likely cause of SpaceX explosion

Posted on 27 Jul 2015 by Michael Cruickshank

New information published by private spaceflight company, SpaceX, has revealed that its recent launch failure was likely caused by single faulty component.

The SpaceX Falcon 9 launch vehicle exploded on June 28 approximately 139 seconds into its flight.

Debris from the failed Falcon 9 rocket falls back to Earth. Image courtesy of NASA Kennedy Space Center.
Debris from the failed Falcon 9 rocket falls back to Earth. Image courtesy of NASA Kennedy Space Center.

Elon Musk, CEO of SpaceX originally tweeted that this explosion was caused by an upper stage “overpressure event”, however the exact cause of this was unknown.

A detailed investigation by the company revealed that this sudden rise in pressure was caused by a cascading series of problems resulting from the failure of single metal strut.

This strut, produced by an outside supplier, was designed to withstand 10,000lbs of force, however failed at around 2000lbs. Its failure caused an internal helium tank within the main propellant tank to break away, and vent its gas.

“It looks like the key strut that holds down one of the helium bottles failed. As a result, the helium bottle would have shot to the top of the tank at high speed,” Musk reportedly explained during a conference call.

With little room for this new gas to expand to, the propellant tank rapidly exceeded its maximum pressure threshold, and subsequently ruptured, destroying the spacecraft.

This diagnosis for the problem was particular difficult to ascertain, due to the rapid speed at which the event occurred.

“From the first indication of an issue to loss of all telemetry was just 0.893 seconds. Over the last few weeks, engineering teams have spent thousands of hours going through the painstaking process of matching up data across rocket systems down to the millisecond to understand that final 0.893 seconds prior to loss of telemetry, ” explained the company in a press statement.

In response to the accident, SpaceX intends to find a new supplier for these struts, of which hundreds are used in each rocket.

Additionally, each of these struts will be tested for weakness before installation in new rockets.

Alongside the announcement of the cause of the crash, SpaceX also revealed that the Dragon capsule could have survived the accident if it had software which would allow it to deploy parachutes in an accident scenario.

Software allowing this was already developed for future manned launches and will reportedly be deployed on future unmanned missions as well.