SpaceX’s Falcon 9 CRS-7 exploded after a strut holding a helium tank broke loose soon after the rocket’s launch from Cape Canaveral.
That’s the word after three weeks of internal investigation by the Hawthorne, Calif.-based company in the wake of the June 28 rocket blast.
More detailed investigation since then showed that a strut used to hold down a helium tank snapped during flight, SpaceX founder and CEO Elon Musk told media in a July 20 teleconference.
“The helium bottle would have shot to the top of the tank at high speed,” Musk said.
The rocket explosion followed quickly after a rapid chain reaction.
“The investigation is ongoing,” Musk stressed. “We are not characterizing this as a definitive result but as a preliminary result.” (audio below)
Musk declined to name the manufacturer of the strut but said SpaceX will change vendors for the component rather than bringing strut production in-house. Helium bottles are stored in the Falcon’s liquid oxygen fuel tank to maintain pressure during flight. (Read the SpaceX summary.)
SpaceX briefed government officials and investors on the preliminary probe results just prior to the media teleconference. During the investigation, SpaceX engineers—overseen by representatives of NASA and the Federal Aviation Administration — culled through 3,000 channels of telemetry data with a hex editor to recover the final milliseconds of the flight.
There was virtually no news regarding the investigation since the rocket mishap, with SpaceX silent even on its Twitter feed. Musk — a billionaire entrepreneur who’s the privately held company’s majority owner — surfaced on his own Twitter feed with a July 5 note to expect an “end of week” update, but one never came.
Founded in 2002, SpaceX has helped ship cargo to the multinational International Space Station. It aims to begin participating in crew shuttles to the station in 2017 with its Dragon spacecraft, supplementing ongoing efforts by the Russians.
A July 10 hearing by the U.S. House Subcommittee on Space examined the impact on the ISS and NASA from a succession of three rocket failures during the past year, including the SpaceX explosion.
SpaceX’s rocket blast caused the simultaneous loss of a Dragon cargo ship, and NASA said the mishap resulted in the loss of $110 million in cargo.
The failed resupply mission was the first attempt at a robotic cargo delivery since April, when a Russian capsule malfunctioned and resulted in the loss of a 3-ton payload. And on Oct. 28, 2014, Orbital Science’s unmanned cargo launch failed just after launch.
“It just goes to show that rockets are fundamentally difficult things,” Musk said of the string of failures.