NASA may be warming to the idea of SpaceX’s “load-and-go” fueling procedure
Although NASA had previously been skeptical over the safety of SpaceX‘s proposed workflow of fueling the Falcon 9 launch vehicle while astronauts were aboard, members on a key safety panel at the agency may now be warming to the idea.
During a meeting on May 17, 2018, members of the Aerospace Safety Advisory Panel (ASAP) appear to have softened their stance on the risks associated with SpaceX’s fueling procedure — colloquially termed “load-and-go” — and have signaled that the process may be compatible with crewed flight.
“My sense is that, assuming there are adequate, verifiable controls identified and implemented for the credible hazard causes, and those which could potentially result in an emergency situation … it appears load-and-go is a viable option for the program to consider,” stated panel member Capt. Brent Jett Jr. (Ret.), as reported in an article by the LA Times.
Historically, NASA has not allowed astronauts to board the spacecraft until the fueling process was complete. However, with SpaceX preferring to load sub-cooled propellant — liquid oxygen (LOX) and RP-1 kerosene — to increase the density of the oxidizer and fuel, the fueling process would occur much later in the countdown, meaning astronauts would board long before fueling is completed.
Critics of the load-and-go process point to the incident on September 1, 2016, in which a Falcon 9 vehicle — and its $185 million AMOS-6 payload — were lost when one of three composite overwrapped pressure vessels (COPVs) in the second stage’s LOX tank failed following a detonation of solidified oxygen in the liner.
Indeed, retired NASA astronaut Thomas Stafford — veteran of four space flights, including Apollo 10 — noted his concern in a letter to William Gerstenmaier, NASA’s Associate Administrator for Human Exploration and Operations, nearly nine months before the incident. Stafford, in his role as a member of the NASA International Space Station Advisory Committee, wrote to Gerstenmaier:
“There is a unanimous, and strong, feeling by the committee that scheduling the crew to be on board the Dragon spacecraft prior to loading oxidizer into the rocket is contrary to booster safety criteria that has been in place for over 50 years, both in this country and internationally. Historically, neither the crew nor any other personnel have ever been allowed in or near the booster during fueling. Only after the booster is fully fueled and stabilized are the few essential people allowed near it.” — Thomas P. Stafford
Others, however, feel the risk is acceptable. SpaceX’s CEO Elon Musk expressed his confidence in the design. When asked, on Twitter, if the capsule would have survived had the escape system activated, Musk replied: “yes [sic]. This seems instant from a human perspective, but it really a fast fire, not an explosion. Dragon would have been fine.”
Though SpaceX has yet to conduct its in-flight abort test, it successfully completed a pad abort test on May 6, 2015. When pundits overlaid the footage of the abort test on the Amos-6 incident, it does appear that the capsule, and its crew, would have been whisked to safety.
Though the fueling process and the COPV failure are two separate issues, they are often conflated. However, it would appear that ASAP members have made peace with the former, though the latter is still an area of concern. To allay that concern, Musk says SpaceX has re-engineered the problematic vessels to make them safer.
“This is by far the most advanced pressure vessel ever developed by humanity. It’s nuts. And I’ve personally gone over the test design – I’ve lost count how many times. But the top engineering minds at SpaceX have agonized over this. We’ve tested the living daylights out of it. We’ve been in deep, deep discussions with NASA about this. And I think we’re in a good situation,” stated Musk in a call held with the media.
With that said, Musk appears to be ready to work with NASA if the agency still feels the fueling risk is too high.
“So I really do not think this represents a safety issue for astronauts. But if, for any reason, that NASA felt different, we can adjust our operational procedures to load propellant before the astronauts board,” concluded Musk.
NASA’s Commercial Crew program is expected to make a final decision on the loading and boarding sequence in the near future.
Curt Godwin has been a fan of space exploration for as long as he can remember, keeping his eyes to the skies from an early age. Initially majoring in Nuclear Engineering, Curt later decided that computers would be a more interesting - and safer - career field. He's worked in education technology for more than 20 years, and has been published in industry and peer journals, and is a respected authority on wireless network engineering. Throughout this period of his life, he maintained his love for all things space and has written about his experiences at a variety of NASA events, both on his personal blog and as a freelance media representative.