NASA's advisory committee is questioning the fueling practices of Space X, which intends to fuel its rocket just before it launches, while the crew is on board the rocket. This fuel practice is concerning to the ISS advisory committee due to the safety risks it puts the crew on.
According to Extreme Tech, Space X uses liquid helium and liquid oxygen, which is kept at cryogenic temperatures, to fuel its rockets. The problem is it's hard to maintain cryogenic cooling for a long time, so Space X opt to load the fuel as close to launch as possible.
Because of this fueling practice, Space X said that once they start their crewed missions to the International Space Station, the crew will already be on board the rocket when they load the fuel. The ISS, understandably, is not crazy about the idea.
This isn't the first time that the ISS committee questioned Space X's fueling practices. Lt. Gen. Thomas Stafford, the chairman of the ISS advisory committee, said in a letter to NASA on December 2015 that fueling the rocket while the crew is on board goes against decades of international space launch policies.
The professor emeritus of the Space Policy Institute at George Washington University, John Logsdon, echoes this sentiment. "I'm not aware that in any other U.S. human spaceflight launch, the booster is fueled after the crew is aboard," he said.
He adds that "it deviates from the norm." It is "bound to raise concerns."
The Australian reports that the ISS committee's warning could further complicate Space X's technical and financial assumptions from transporting crews to and from the space station. Flights are anticipated to begin later this decade.
Concerns of the crew's safety also put the responsibility on NASA leaders if they will authorize this kind of practice. A NASA official that was assigned to the meeting with the ISS advisory committee last Oct. 31 said the committee could expect a briefing in December.
NASA said that they are working through a "rigorous review process" with both companies and will continue to evaluate Space X's processes for fueling the Falcon 9 for commercial crew launches. The agency will also incorporate into their evaluation the result of the investigation on the September 1 explosion.
The good news is Space X said they could recreate the problem to be able to find a solution. The bad news is that the rocket's current fueling system can cause it to explode, which is an unwelcome risk if the rocket will be carrying space crew.