2/x: NASA confirms "minimal propellant operations" on the ICPS (interim cryogenic propulsion stage) with a heavily modified Wet Dress on Thursday, April 14 focusing on the Core Stage with T0 slated for 14:40 EDT / 18:40 UTC.
3/x: "We think this is a great path forward" said NASA official.
4/x: Charlie Balckwell-Thomson says "chill down ops" for the upper stage -- indicating no propellant flow to the ICPS will occur. "Believe we can meet majority of test objective prior to roll back."
5/x: They do still plan to count beyond 10 minutes into terminal count, cutoff, recycle and then count back down to T-9.34 seconds and then cut-off and scrub... ending the Wet Dress Rehearsal.
6/x: The issue with the helium check valve on the ICPS. Helium supply inlet leakage on ML was found and replaced. They had to reduce COPV (pressure vessel) on ICPS, & when they repressed it, didn't see proper pressurize valves. Issue identified as being with flight hardware.
7/x: This appears to be the first flight hardware issue identified in the wet dress. All others had been ground-side of the system.
8/x: Reverse flow check on the helium check valve should have stopped all helium flow. It did not, so the check valve is bad. It's only 3 inches (76 mm) long. And it's a "high-reliability part" according to NASA. So failure was unexpected. Just can't access on pad; only VAB.
9/x: Sounds like this helium check valve had been operating fine, but it was after equipment swap out at the pad after last Monday when it didn't work.
10/x: How do you have confidence ICPS will work if you don't wet dress it? Charlie confirms ICPS fueling was a big part of wet dress and says data from wet dress will drive their decision. (From me: But if they don't fuel in wet dress, how can they get that data?)
11/x: COPVs in the ICPS are pressurized at this time; NASA just aren't adding more pressure at this time due to the failed helium check valve.
12/x: NASA confirms that the ICPS helium check valve is the first flight-side issue seen during wet dress. That is encouraging across the board given first-time ops for this vehicle.
13/x: Charlie running through that the only critical thing they won't get from the modified wet dress is the ICPS cryo data. They'll still get everything else. Just not the ICPS data.
14/x: There are 25 critical terminal count (T-10mins and under) items. 2 are related to the ICPS, so they'll get 23 of the 25. Overall, there are about 3 of 75 critical things in wet dress they won't get by not fueling the ICPS.
15/x: Point of the helium check valve is so that on launch they don't evacuate pressure during ascent.
16/x: NASA now saying they'll flow "cold gas" right up to the point where they'd load propellant. This will allow leak checks at cryogenic temperatures. But does not sound like propellant will flow into the ICPS... they'll just cool it does to cryo leak check it.
17/x: A couple Ground Launch Sequencer commands will not be able to be sent as they will have to on launch day in the modified wet dress count for Thursday.
17/x: When asked how they'll use data gathered to inform ICPS forward decisions if that data won't include fueling, Charlie answers from a Core Stage and Booster perspective then notes they'll look at what they didn't get from ICPS & then make a decision based on all of that.
19/x: Artemis 1 launch windows at this point: June 6-16 then June 29-July 17 then July 26-Aug 9.
20/x: Rollback plan: After wet dress, about 10 days to roll back under nominal timeline. Rollback was already planned as part of the forward path to Artemis 1's launch and is not an ICPS-only related operation.
21/21: That's all from this telecon.
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