Artemis II's next Wet Dress Rehearsal this week

I should say it will probably be this coming week or something more tentative than just saying it'll definitely be this week.  

There was a fueling test last week that wasn't hyped about in advance, it just suddenly got announced while we all seemed to be concentrating on the coming Crew-12 launch. Today we learned that they're planning more tests fueling WDRs due to some things noticed during that test - not just the previous (Feb. 2nd) WDR test that failed. 

NASA Administrator Jared Isaacman said today (Saturday Feb. 14) the agency is looking at ways to prevent the fueling problems but didn't say before Artemis II's flight; he said before Artemis III.

There were a couple of interesting statements made about the WDR test that made Looney Tunes-style question marks appear in the air above my head. 

First:

Fuel leaks are nothing new for the Space Launch System. The same kind of leak delayed the first test flight of the SLS rocket for several months in 2022. With that launch, ground teams thought they fixed the problem by changing how they load super-cold liquid hydrogen into the rocket’s core stage. The launch team used the same loading procedure February 2, but the leak cropped up again. 

That means a "fix" that worked for Artemis I was duplicated on this Artemis II SLS and it didn't work? It only worked once, on one system? That's not an encouraging outcome; it implies there's so much variation from unit to unit that you can never know if a given rocket will work properly. They're one-of-a-kind systems, not consistently built. Today's buzz word would be bespoke instead of manufactured. Maybe custom made. The big issue there is not knowing if something that fixed a problem before will ever fix it again.

Second:

Isaacman wrote Saturday that the test “provided a great deal of data, and we observed materially lower leak rates compared to prior observations during WDR-1.”

So this week's test, had "materially lower leak rates" than the first run of a WDR and they didn't give it a "passing" mark? 

During the first WDR earlier this month, hydrogen gas concentrations in the area around the fueling connection spiked higher than 16 percent, NASA’s safety limit. This spike was higher than any of the leak rates observed during the Artemis I launch campaign in 2022. Since then, NASA reassessed their safety limit and raised it from 4 percent —a conservative rule NASA held over from the Space Shuttle program—to 16 percent. 
...
John Honeycutt, chair of NASA’s Artemis II mission management team, said the decision to relax the safety limit between Artemis I and Artemis II was grounded in test data.

“The SLS program, they came up with a test campaign that actually looked at that cavity, the characteristics of the cavity, the purge in the cavity … and they introduced hydrogen to see when you could actually get it to ignite, and at 16 percent, you could not,” said Honeycutt, who served as NASA’s SLS program manager before moving to his new job.

Another way of interpreting all this is that NASA used the three-year delay between Artemis I and Artemis II to get more comfortable with a significant hydrogen leak, instead of fixing the leaks.

Doesn't sound good? Doesn't sound even slightly professional? NASA chief Jared Isaacman said, “I will say near-conclusively for Artemis III, we will cryoproof the vehicle before it gets to the pad, and the propellant loading interfaces we are troubleshooting will be redesigned.”

Back for the Artemis I mission, during the months of fighting hydrogen leaks, they were found to be from ground support equipment. 

Specifically, the hydrogen leaks originate in the area where fueling lines on the rocket’s launch platform connect to the bottom of the core stage. Two Tail Service Mast Umbilicals, or TSMUs, route liquid hydrogen and and liquid oxygen into the rocket during the countdown, then disconnect and retract into protective housings at liftoff. 

The TSMU supplying liquid hydrogen to the core stage has two lines, 8 inches and 4 inches in diameter, connecting through matching umbilical plates on the ground side and the rocket side. Technicians replaced seals around the two fueling lines after the practice countdown, or Wet Dress Rehearsal (WDR), earlier this month.

The full Moon is seen behind the Space Launch System rocket at NASA’s Kennedy Space Center in Florida. The Tail Service Mast Umbilicals (TSMUs) are the gray structures that extend above the launch platform on the bottom left of the core stage. Credit: NASA/Ben Smegelsky

I didn't think I could get a lower opinion of SLS than I already have.