NEW YORK — SpaceX said Oct. 28 that it is able to replicate the failure of a helium tank that is suspected, but yet to be confirmed, as the cause of a Falcon 9 pad explosion nearly two months ago.
In a statement, the company said it is focusing its investigation on tanks made of fiber composite materials used to store helium within the liquid oxygen propellant tank of the Falcon 9's second stage. In its last public statement about the investigation, issued Sept. 23, the company said the cryogenic helium system in the propellant tank suffered a "large breach" immediately before the explosion.
"The root cause of the breach has not yet been confirmed, but attention has continued to narrow to one of the three composite overwrapped pressure vessels (COPVs) inside the [liquid oxygen] tank," SpaceX said in its new statement.
The company said it's able to replicate the failure of a helium tank based on the condition of the helium being loaded into it. "These conditions are mainly affected by the temperature and pressure of the helium being loaded," SpaceX said.
The new statement appears to confirm recent statements by company officials that suggested an issue with how the launch vehicle is prepared for launch, and not a flaw with the vehicle itself, caused the explosion during preparations for a static-fire test. SpaceX President Gwynne Shotwell, speaking at the annual meeting of the National Academy of Engineering Oct. 9, said the company was "homing in" on the cause of the accident, adding she felt it unlikely it was caused by "a vehicle issue or an engineering design issue but more of a business process issue."
In comments that leaked out after an Oct. 13 presentation at the National Reconnaissance Office, SpaceX Chief Executive Elon Musk suggested solid oxygen formed within one of the COPVs. "Under pressure it could have ignited with the carbon," he said, according to a leaked transcript of his speech. "This is the leading theory right now, but it is subject to confirmation."
SpaceX said it's continuing to seek the root cause of the pad explosion while also preparing for a return to flight. "SpaceX's efforts are now focused on two areas – finding the exact root cause, and developing improved helium loading conditions that allow SpaceX to reliably load Falcon 9," the company stated. It added it will soon resume tests Falcon 9 stages at its Texas test site as "an important milestone" towards resuming launches.
Those launches, the company said, will resume from the company's pad at Vandenberg Air Force Base in California and Launch Complex 39A at Florida's Kennedy Space Center, both of which the company said "remain on track to be operational" to support a return to flight before the end of the year. The company has not disclosed the damage that Space Launch Complex 40 at Cape Canaveral suffered in the pad explosion or when it would be able to resume hosting launches.
Josh Brost, director of government business development at SpaceX, said at the American Astronautical Society's Wernher von Braun Memorial Symposium Oct. 26 in Huntsville, Alabama, that the company was "less than a month" from formally activating Launch Complex 39A for Falcon 9 launches. "39A is where we'll return to flight on the East Coast, hopefully later this year," he said.
SpaceX's customers, meanwhile, are also hoping that the company returns to flight this year. "We've been on hold since SpaceX's launch pad incident at Cape Canaveral eight weeks ago and have been following the investigation closely to determine when SpaceX will be able to return to flight," said Matt Desch, chief executive of Iridium, during an Oct. 27 conference call. Prior to the pad explosion that destroyed the Amos-6 satellite, Iridium was scheduled to fly next, launching the first ten of its Iridium Next satellites from Vandenberg.
Desch said on the call that Iridium is participating in SpaceX's accident investigation team and believes "SpaceX is conducting a very thorough process" in that investigation, but declined to speculate when SpaceX would be ready to start launching Iridium's satellites.
"I remain hopeful that they'll return to launching this year," he said. "Also, I don't know if Iridium Next will be SpaceX's first launch once they return to flight or whether they might schedule a launch from Florida ahead of us. Either way, we're comfortable with SpaceX's investigation and the progress they're making and I assure you that we won't proceed to launch if we aren't confident in SpaceX and their investigation outcome."
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