After nearly two years of debate, NASA has finally approved SpaceX’s plans to load propellant onto its rockets with people on board — a move that has been considered risky by some aerospace experts. However, the approval is contingent upon one thing: SpaceX must successfully demonstrate this fueling method at least five times on its new upgraded Falcon 9 rocket, the Block 5, before the process is certified for human spaceflight.
NASA announced this decision late Friday on its website, saying that safety was the space agency’s priority when moving forward with this. “To make this decision, our teams conducted an extensive review of the SpaceX ground operations, launch vehicle design, escape systems, and operational history,” Kathy Lueders, manager of NASA’s Commercial Crew Program said in a statement. “Safety for our personnel was the driver for this analysis, and the team’s assessment was that this plan presents the least risk.”
SpaceX has long relied on a fueling process that’s referred to as “load and go,” in which the company pumps propellant into its rocket just a half hour before launch. That’s fairly close to liftoff compared to other launch providers, such as the United Launch Alliance, which fuels its Atlas V rocket an hour and a half before launch. The procedure is ideal for SpaceX, though, since the company uses extremely cold propellants, and fueling the vehicle just before takeoff limits the propellant from warming up too much and boiling away. It also increases the performance of the rocket.
However, this means that when SpaceX starts flying NASA astronauts for the Commercial Crew Program, passengers will have to board the rocket before propellant has been loaded. That idea hasn’t sit well with a few safety experts, notably Air Force Lt. General Thomas Stafford, who chairs NASA’s ISS Advisory Committee which provides oversight of the space agency’s projects. The load and go approach would mean that the bulk of fueling would occur with people already on board and that loading propellants was a “hazardous operation” that shouldn’t occur near people. The committee cited SpaceX’s accident in 2016, which occurred when one of the company’s Falcon 9 rockets exploded while it was being loaded with propellant for a test.
Since then, SpaceX has lobbied that the process is safe, though CEO Elon Musk said it’s possible for the company to do a different loading procedure. “I think that issue has been somewhat overblown,” he said during a press call in May. “We certainly could load the propellants and then have the astronauts board Dragon. That’s certainly something we could do.” However, NASA has warmed to the idea in recent months. Members of NASA’s Aerospace Safety Advisory Panel, who oversee the safety of various space agency projects, said that the procedure was a “viable option” during a meeting in May.
Now, SpaceX will have to do its five-time demonstration of load and go before it can use the process with humans. The company has numerous missions planned before people are supposed to fly on the Falcon 9 for the first time in April of 2019, so there’s plenty of months left to certify the process. However, SpaceX still needs to provide a key update to its rocket before it can start these demonstrations. The company has to add upgraded helium tanks to its Falcon 9, called COPVs, before the vehicle is in its final form for launching crew members. Those COPVs aren’t slated to fly until November, when SpaceX launches its first Crew Dragon capsule without people on board.
So sometime between November and April, SpaceX will have to do five flights of load and go. After that, NASA will figure out of there is any “remaining risk” before certifying the procedure for crew.
via The Verge https://ift.tt/2OMyZxM