Fuel leak delays NASA's Artemis 1 moon mission launch

[Admin]

A fuel leak forced NASA to call off its second attempt to launch the Artemis 1 moon mission on Saturday (Sept. 3).

Fuel leak delays NASA's Artemis 1 moon mission launch : Read more

 

[Unclear Engineer]

Liquid hydrogen is tricky stuff. But, I would think that the NASA teams would have the experience by now to make this fueling operation with LH go more smoothly than this.

Liquid methane is a lot easier to work with - not as cold and doesn't do strange things like climb tank walls. SpaceX seems to have made a good choice for quickly reuseable space vehicles, not to mention in-orbit refueling issues

 

[muhrich]

Just curious, how come we could do this in 1969 with ancient technology but not in 2022 after $93 billion

 

[Unclear Engineer]

Just curious, how come we could do this in 1969 with ancient technology but not in 2022 after $93 billion

I am tempted to say "Lack of practice." But, other rockets have used liquid hydrogen in the intervening 50 years. So, that should not be the answer.

Actually, holds to fix problems are not so unusual - it is the attention on the preparations that is unusual for this particular launch. Usually, we just hear about a launch on the news after it happens, and the public never hears about the holds and usually nothing about the scrubs, either.

Part of the problem this time may be the political pressure to get the bird off the ground. They never did get all the way through a "wet rehearsal", which is what should have showed them the problem with the temperature sensor. And, this leak seems to be repeating itself. If they had found these equipment problems in a wet rehearsal, then rolled it back to the Assembly Building and repaired them, this would probably have gone smoother.

But, actually, nothing is lost compared to having tried to go for a launch, instead of doing another try at a completed wet rehearsal without launching right after it went perfectly.

 

[JLB39401]

My question now is -- these tanks have a definite service life; every time they are pressured up, they take stress; every time they are loaded with hydrogen, they are slightly embrittled -- with all the repeated load/unload cycles, are these tanks now approaching end-of-life? Is the damage repairable at all, or will it just be like putting a tiny band-aid on a shattered Hoover dam?

 

[billslugg]

Tanks can be fueled up 22 times. There have been three fuelings, June 20, Aug 29, Sept 3.


" The tanks can be loaded up to 22 times for testing and launches. " -
Artemis – Page 19 (nasa.gov)

 

[billslugg]

Lest we forget, the Shuttle was brought back to the VAB 20 times before it went off.

Paragraph 5:

Artemis I's next launch attempt may not happen until later this year | CNN

A second attempt at launching the uncrewed Artemis I mission was scrubbed Saturday after experiencing fueling issues. Future launch attempts may not occur until later this year, like launch periods in September and October, according to an update from NASA.

www.cnn.com

EDIT: NOT before it went off the first time but during the entire program.

 

[JLB39401]

Tanks can be fueled up 22 times. There have been three fuelings, June 20, Aug 29, Sept 3.


" The tanks can be loaded up to 22 times for testing and launches. " -
Artemis – Page 19 (nasa.gov)

Thank you for the link, but you have missed a few fuelings. There were three WDR attempts in April; plus the (at least one) fueling for the Green Run. There were likely more than that; but I do not have a complete list handy.

 

[billslugg]

Yes, thank you for the corrections. I left out the April runs because, as best I could tell, they did not fully fuel. So with the Green Run there have been at least 4 full fuelings, perhaps more. Still we are no where near the end of life on these systems.

 

[Unclear Engineer]

I would expect that the stress/embrittlement episodes are more a function of cool-downs and reheats, rather than the weight of the propellant.

And, I would expect that the tanks were checked for leaks at least once before being assembled into a core stage, and probably at-temperature.

So, we probably can't really count the number of events that NASA is counting against their limit of 22. And, the limit itself may not start until the core stage is completed.

Whatever the counting process, I expect that the limit has a large factor of safety built-in. Nobody wants to be riding a rocket where it is expected to fail "next time, on-average".

 

[Dratonia]

Also, remember, if NASA says that the rocket's life cycle is 20 refuelings, it could probably take 40 before critical failure. If there is one thing that NASA is good at, it's extreme caution and redundancy.

 

[billslugg]

Also remember that no human lives are at stake when launching this vehicle. So what if one of the tanks cracks during a fill or during a launch? We lose a vehicle and some propellant. It would cost about the same to scrap it.

 

[Unclear Engineer]

Also remember that no human lives are at stake when launching this vehicle. So what if one of the tanks cracks during a fill or during a launch? We lose a vehicle and some propellant. It would cost about the same to scrap it.

I don't think that is true. If the hydrogen tank fails in any serious way while the vehicle is anywhere near the launch platform, there would be a lot of collateral damage, especially since the abort system would probably be used to destroy the vehicle.

And, then there would be the inevitable delays while NASA "studies" the failure and begs Congress for more funds, with a bad political blemish on the execution of the program hindering the political approval process.

 

[Dratonia]

I don't think that is true. If the hydrogen tank fails in any serious way while the vehicle is anywhere near the launch platform, there would be a lot of collateral damage, especially since the abort system would probably be used to destroy the vehicle.

And, then there would be the inevitable delays while NASA "studies" the failure and begs Congress for more funds, with a bad political blemish on the execution of the program hindering the political approval process.

Well yes, but I don't see how this would end up being that much worse than what would happen if they scrap the project. If anything, it would show how they need more funding than they currently have, as it would show that reusing old surplus equipment runs the serious risk of explodey bits going everywhere.

 

[billslugg]

There are no people allowed on the pad during fueling. The blockhouse is designed to handle an on pad explosion of a fully fueled vehicle. In fact, NASA has registered concern over SpaceX's fueling while astronauts are in the capsule.

We are already operating under a waiver of the 20 day rule for the launch abort system.

Safety Panel Cites Concerns Over SpaceX Fueling Process for Commercial Crew | Space

 

[Dratonia]

There are no people allowed on the pad during fueling. The blockhouse is designed to handle an on pad explosion of a fully fueled vehicle. In fact, NASA has registered concern over SpaceX's fueling while astronauts are in the capsule.

We are already operating under a waiver of the 20 day rule for the launch abort system.

Safety Panel Cites Concerns Over SpaceX Fueling Process for Commercial Crew | Space

Safety, safety, safety!

Man, I love NASA.

 

[Unclear Engineer]

Now that the article about SpaceX fueling strategy is 5-year "old news", what was the outcome? SpaceX has now launched several crewed flights.

Loading kerosene is not as difficult as loading liquid hydrogen, so not really directly comparable to the SLS fueling issues that have scrubbed this flight. Even loading liquified methane is not as difficult as loading liquified hydrogen, or even liquified oxygen.