Of course, we don’t know the root cause of the helium flow problem on the stage yet. It could be something that happened after ULA delivered it to NASA after all. There’s been plenty of time for that.

Indeed, as I pointed out explicitly on Bob’s SLS delay thread yesterday!

Striking, then, that this most flight proven stage on the entire stack is the one that has somehow managed to force a rollback to the VAB. Could it be the result of having been sitting in storage at NASA for nearly five years, rather than, say, bad Boeing workmanship?

Now, that said, a cursory bit of research suggests that at least one Delta IV launch was forced into a lengthy (multi-week) launch delay by problems in its DCSS. Perhaps there were more; I’d have to keep looking.

Otherwise, maybe it’s not unreasonable to have an impression of the ICPS/DCSS as much of a piece with Boeing/McDonnell Douglas hydrolox launch endeavours of this last generation: generally capable, but quite finicky, and exuberantly expensive.

And flew successfully 46 times on Delta IV and SLS.

Tim: Then it was simply a timing issue. You probably checked just before I posted. No big deal.

“After overnight data showed an interruption in helium flow in the SLS interim cryogenic propulsion stage, teams are troubleshooting and preparing for a likely rollback of Artemis II to the VAB at @NASAKennedy. This will almost assuredly impact the March launch window. @NASA will continue to provide updates as they become available.” — NASA Administrator Jared Isaacman

https://x.com/i/status/2025231621436186837

P.S. Jared fields a question from one of the NSF guys:

Q: “I have a question… Does this mean that it was an overnight data review of the WDR or is it that the helium flow interruption happened overnight?”

Jared: “The ICPS helium system performed as expected during both WDRs. This was an unexpected development during routine helium flow operations last evening. The teams were up all night assessing the situation.”

I will just note for the record that the ICPS was designed by . . . Boeing.

Tim: Refresh your browser. I posted about this two hours ago.