Spaceflight Insider

NASA may be warming to the idea of SpaceX’s “load-and-go” fueling procedure

SpaceX Crewed Dragon spacecraft in orbit above Earth. Image Credit: Nathan Koga / SpaceFlight Insider

Image Credit: Nathan Koga / SpaceFlight Insider

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.

SpaceX Falcon 9 v1.1 Pad Abort Test Cape Canaveral Air Force Station Space Launch Complex 40 SLC-40 photo credit Mike Howard SpaceFlight Insider

The pad abort test was conducted before the Amos-6 pad incident. Would the escape system have protected crew and craft? Photo Credit: Mike Howard / SpaceFlight Insider

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.

SpaceX's spacesuit next to a Crew Dragon capsule. Photo Credit: Elon Musk / SpaceX

SpaceX’s spacesuit next to a Crew Dragon capsule. Photo Credit: Elon Musk / SpaceX

 

 

 

 

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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.

Reader Comments

So Thomas is going by safety protocols based on outdated designs? Ok.

SpaceX rockets are an entirely new design compared to what Thomas is used to & SpaceX has heavily modified the refueling system for the Falcon 9 at the pad. SpaceX rockets arent the 20th century dinosaur rockets that Thomas is used to. They are getting much safer now. The risk is still there & probably will never go away so the less time crew is exposed to fuel the better. That’s the whole point of the ‘load & go’ refueling process

jeffrey Root

The point of load and go is to get as much super cooled LOX on board for landings. The longer the rocket sits on the pad the LOX warms and becomes less dense, which means less room to pump in enough fuel for landings. If they weren’t doing landings the load and go would be unnecessary. With that said, I support load and go. The new pressure vessels can withstand double the pressure they used to. Some risk needs to be involved in spaceflight and lets face it, the Shuttle was more of a risk because it did not have a launch abort system or the ability to shut off the SRBs, leading to the Challenger incident. It was also attached to the side of a giant fuel tank with foam that slammed into the shuttle tiles, leading to the Columbia incident.

Dennis Payne

NASA is correct that the vehicle is going through pretty crazy changes during the fueling event: Temperature, Pressure, Weight, …

They are also correct when saying that the vehicle is relatively stable some number of minutes after fueling.

However, if the escape system can mitigate concerns during fueling… then the issue is: Is it safer to board a vehicle that has or has not been fueled? The answer seems to be an obvious one. Your exposed astronaut body won’t get vaporized if there is no fuel around.

I understand the fueling process of the Falcon 9 takes about 30 minutes or less as compared to the hours taken by earlier NASA flights. Putting astronauts on board after fueling would probably take ten minutes or so with a check down. During that time they would be completely exposed to any catastrophic occurrence. If the escape system works as demonstrated I would think they would be safer on board with “load and go”.

The load crew after fueling argument seems entirely based on, “we’ve always done it this way” reasoning. The space shuttle was in itself a huge compromise in terms of safety (ie. No abort system) and it is amazing someone actually signed off on it. Loading crew onto an inert, unfueled vehicle kinda makes sense. Abort systems are exactly there for if things go wonkey, be that during launch or indeed fueling. This “what we don’t know is probably bad” attitude is not always healthy. Loading crews onto a pre-fueled Amos 6 would have been infinitely more dangerous than doing a crew preloading with a armed abort system during fueling.

I have no idea if they could do it, but I think it would be… interesting to do an abort that is essentially bolting the capsule to a Grasshopper and lighting it off at some angle. Basically set up what should be detected as an amomalous situation, bonus points for inducing a tumble, and let the system figure it out, light off the engines to escape and orient, then chute and if necessary retro-cushion (seems like a mistake to assume a failure will direct it over water?).

If the crew capsule initiates a separation from the rocket at the moment of the explosion, it very likey that the crew will experience lethal g loads. The trick is to initiate a crew capsule separation BEFORE any explosion. What sensor readings will qualify for initiating a separation and what sensor readings will not qualify for initiating a separation. That is the question.

Spacex often delay their launchs on the last minutes then left the fuel and LOX inside the rocket at the launch pad. Therefore, in theory,there should not be any problem fueling the rocket first then load the crew?

Just to say that when they say the crew would have been safe after the abort – they mean – possibly with life changing injuries, but alive. The abort is so forceful, they don’t test it with a human but only with a dummy. There is no way they are going to test it with live humans. It is meant as a last resort and shouldn’t be relied on as a routine thing.

On the other hand it’s only 6 g from Elon Musk’s tweet.

https://twitter.com/elonmusk/status/596053122587365376

That’s not so bad, it’s survivable for sure, it’s possible that the crew have no injuries also. But still, high enough that they are only going to test with crash dummies if I understand right. If there is a pad abort it will be the first time it’s ever happened with living humans instead of crash dummies.

Just thought that needed clarification. If they are coming around to saying this process is okay it will mean they think this is something that is not likely to happen ever. I don’t think they would approve it if they thought, say, that the abort will be triggered in 1 in 20 flights.

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