Article by: James Dean
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SpaceX is targeting a Sunday, Jan. 8, return to flight of its Falcon 9 rocket from California, where the company will adjust fueling procedures believed responsible for a Sept. 1 explosion that destroyed a rocket and satellite on their Cape Canaveral launch pad.
A four-month investigation pinpointed failures in the system that uses cold helium gas to pressurize propellant tanks filled with super-chilled liquid oxygen, SpaceX said.
Investigators found buckles had formed in the aluminum lining of helium tanks that are about as large as a person.
When the system was pressurized, the buckles trapped pools of liquid or solid oxygen between the linings and an outer layer of carbon wrap covering them. That build-up of oxygen likely created friction or caused carbon fibers to break, SpaceX said, which ignited the oxygen in the rocket’s upper stage during a countdown rehearsal at Cape Canaveral Air Force Station’s Launch Complex 40.
The Falcon 9 and Spacecom’s $200 million Amos-6 commercial communications satellite, which Facebook had hoped to use to extend Internet access in Africa, were lost, and the launch pad was severely damaged.
In an update posted online Monday morning, SpaceX, led by Elon Musk, said the helium tanks will be redesigned, but did not specify when that longer-term change would be implemented.
To prevent buckling in the short-term, the company said it would revert to “a prior flight proven configuration” for loading helium, including loading the gas at a warmer temperature. Those procedures have worked safely more than 700 times, SpaceX said, but take more time.
The planned Jan. 8 launch from Vandenberg Air Force Base will carry the first 10 of at least 70 communications satellites that SpaceX is contracted to launch for Iridium Communications.
As it did through much of the first half of last year, SpaceX plans to try to land the Falcon 9’s first stage on a modified barge in the ocean, continuing efforts to recover and re-launch Falcon boosters.
Before Sunday, SpaceX plans to fuel the Falcon 9 for a practice countdown like the one performed on Sept. 1, intended to end with a brief firing of the rocket’s nine Merlin main engines. This time, no payload will be on top.
If the return to flight succeeds, a Falcon 9 could try to launch an unmanned Dragon cargo ship to the International Space Station from Kennedy Space Center before the end of the month.
The Sept. 1 explosion was the second time in 14 months that a Falcon 9 suffered a catastrophic failure. In June 2015, another breach in the upper-stage liquid oxygen tank doomed a Dragon mission to the ISS about two minutes into flight. SpaceX said that problem, attributed to a failed strut, was unrelated to the Sept. 1 explosion.
SpaceX led the recent investigation with oversight from the Federal Aviation Administration, which licenses commercial rocket launches. Other partners included NASA, the Air Force, the National Transportation Safety Board and several unidentified “industry experts.”
“SpaceX greatly appreciates the support of our customers and partners throughout this process, and we look forward to fulfilling our manifest in 2017 and beyond,” the company said in a statement.
Drawing from more than 3,000 channels of data from video and telemetry, the investigation focused on an instant — less than a tenth of a second — from the first sign of trouble to the rocket’s destruction.
For weeks after the accident, Musk did not rule out the possibility that someone might have fired a shot at the rocket.
NASA has been performing its own, independent investigation and has not yet released any findings.
The space agency relies upon SpaceX to deliver cargo to and from the space station, and also hopes to see the company launch astronauts to the outpost in early 2018.
SpaceX’s late fueling of the Falcon 9 during the final half-hour of countdowns, when a crew would be sitting atop the rocket, has been a source of concern to NASA and some of its independent safety advisers.