SpaceX discovers cause of Falcon 9 rocket explosion

SpaceX CEO Elon Musk has said his company has finally solved the mystery of what caused their Falcon 9 rocket to explode back in September, and that he anticipates returning to flight by the middle of next month, according to CNBC and The Verge reports late last week.

Calling the incident the “toughest puzzle” his company has ever had to solve, Musk said that the cause “basically involves liquid helium, advanced carbon fiber composites, and solid oxygen.” In short, what that means is that the supercooled liquid oxygen that SpaceX uses as a propellant had become so cold that it actually became a solid – which, obviously, should not happen.

The Verge hypothesizes that the solid oxygen may have reacted poorly with the Falcon 9’s liquid helium pressure vessels, which are located inside the upper oxygen tank of the spacecraft (where the propellant is contained). The three containers are designed to fill and pressurize empty spaces that remain after the propellant leaves the tank, and could have caused solid oxygen remaining in the tank to ignite, causing the explosion that led to the booster’s destruction.

SpaceX has not provided any additional comment on the matter, and it remains unclear what may have caused the oxygen to solidify in the first place. The New York Times has speculated that the pressure vessels may have used liquid helium, which at -452 degrees Fahrenheit might have been cold enough to solidify the liquid oxygen (which happens at -361 degrees Fahrenheit).

Details for proposed December mission currently unknown

While Musk told CNBC that he is confident that the company has “gotten to the bottom of the problem” and will return to flight prior to the end of the year, he did not provide specifics about what mission SpaceX would attempt next, nor what facility the firm planned to launch from.

According to Reuters, the company has a backlog of nearly 70 missions worth a combined $10 billion, and while they use a primary launch pad located south of Kennedy Space Center in Cape Canaveral, Florida, that site was damaged in the September explosion. That leaves SpaceX with two options: a new launch pad at Kennedy, or a West Coast launch pad located in California.

Musk’s statements follow similar comments made by Rupert Pearce, chief executive of Inmarsat, who according to Space News said last week that his company (which has three satellites that are currently awaiting transport on Falcon 9 and Falcon Heavy booster rockets) believes that Musk’s company had “found a root cause” that could be fixed “quite easily and quite quickly” and would be able to return to flight sometime next month.

The Falcon 9 was being fueled for a routine preflight test on September 1 when it exploded, causing the loss of a 200 million Israeli communications satellite, Reuters said. Musk called the cause of the incident, which marked the second time in a 14 month span that an issue caused the booster fleet to be grounded, something that had not previously seen in the field of rocketry.


Image credit: SpaceX