SpaceX announced Monday that its Falcon 9 rocket could resume launches on January 8. The Elon Musk-led company has concluded the investigation into an explosion that destroyed a Falcon 9 rocket and a satellite on September 1. The Federal Aviation Administration is yet to issue a launch license to SpaceX, but sources told Space.com that the FAA had received SpaceX’s report on launch pad accident, and was reviewing it.
The launch date could change
Industry officials told the Wall Street Journal that the tentative launch date of January 8 could still change, depending on results of testing later this week and issuance of launch license by the FAA. SpaceX said that the explosion was due to problematic fueling procedures rather than a design flaw. Just a few minutes before the blastoff on September 1, a pressurized helium tank within the second-stage liquid oxygen tank had ruptured.
SpaceX said its experts analyzed 3,000 channels of telemetry and video data spanning just 93 milliseconds from the first sign of the problem to the explosion. The company conducted the probe in cooperation with NASA, the Federal Aviation Administration, the US Air Force, and other experts.
What caused the explosion?
Investigators concluded that the failure of helium tank, known as composite overwrapped pressure vessel (COPV) within the liquid oxygen tank was triggered by several variables including temperature and pressure. The accident was due to the accumulation of oxygen between the COPV’s aluminum liner and composite overwrap. A COPV is made using an aluminum liner surrounded by a carbon fiber composite overwrap.
Investigators found that supercooled oxygen fuel pools in a “void or buckle” in the aluminum liner, breaking the composite fiber. The temperature of the helium is also cold enough to freeze the liquid oxygen, worsening the problem. SpaceX said it identified “several credible causes” for the COPV failure. And all of them involve the accumulation of supercooled oxygen in buckles under the carbon overwrap.
Iridium remains confident in SpaceX
In the short-term, the company will change the procedures for fueling the rocket. It plans to use warmer helium in the COPVs, and load helium at a slower pace. SpaceX said it would return to “flight proven” fueling procedures that have been used in more than 700 successful COPV loads. In the long-term, the company will make design changes to prevent buckling altogether.
If everything goes as per the plan, Iridium Communications will see the first ten of its communications satellites being placed into the low Earth orbit on January 8. Iridium said last month that it remained confident in SpaceX’s ability to “safely deliver our satellites into low-Earth orbit.”