So, SpaceX is pretty sure it can pin the September explosion on the helium pressure vessel, the carbon-fiber-wrapped beastie that gave out while it was being filled. But there’s an advisory committee at NASA that thinks SpaceX has a whole different problem with their fuel handling procedures. To wit: SpaceX intends to fuel its rocket right before launch, with the crew already aboard, and the ISS advisory committee understandably isn’t crazy about that idea.
SpaceX fuels its rockets with liquid helium and liquid oxygen, kept at cryogenic temperatures in order to fit as much fuel as possible. It’s hard to maintain cryogenic cooling for too long, though, so they load the LOX and helium tanks as close to launch as they can. Because of that timing, when SpaceX eventually starts running crewed missions to the International Space Station, SpaceX said that the crew will be on board the spacecraft while the propellant tanks are being loaded. During that time, the Dragon’s abort system will be enabled.
This isn’t the first time the ISS committee has called into question SpaceX’s fueling procedures. In a letter to NASA from December 2015, ISS advisory committee Chairman Lt. Gen. Thomas Stafford said fueling a rocket with the crew on board went counter to decades of international space launch policies.
“I’m not aware that in any other U.S. human spaceflight launch, the booster is fueled after the crew is aboard,” John Logsdon, professor emeritus of the Space Policy Institute at George Washington University, told the LA Times. “It’s a deviation from the norm, and that’s bound to raise concerns.”
It’s not like NASA doesn’t have their eyes on the problem; NASA said it is working through a “rigorous review process” with both companies and will continue to evaluate SpaceX’s process for fueling the Falcon 9 rocket for commercial crew launches.
The results of the explosion investigation will also be incorporated into NASA’s evaluation, the agency said. SpaceX, for its part, has said that it can recreate the accident “entirely through helium loading conditions.” That’s a mixed-news assessment. The good news is that SpaceX knows exactly how to recreate the problem; the bad news is that the spacecraft’s current fueling system can cause the rocket to explode. Granted, this is more or less true for a number of rockets, but that the crew would be sitting on top of the rocket while its fueled adds an unwelcome element of risk.