Who knew that liquid hydrogen could have leak issues?
Notice the subtle shade from Jared: ““With more than three years between SLS [Space Launch System] launches, we fully anticipated encountering challenges.”
[Update a few minutes later]
[Late-morning update]
The Artemis vision began with President Trump, but the SLS architecture and its components long predate his administration, with much of the heritage clearly traced back to the Shuttle era. As I stated during my hearings, and will say again, this is the fastest path to return… https://t.co/bu0SvThwS9
— NASA Administrator Jared Isaacman (@NASAAdmin) February 3, 2026
It’s not even the fastest path, but it is probably the one with lowest risk. We could get back to the Moon faster and at lower cost, but we’d have to accept more risk than NASA and Congress have demonstrated the ability to do.
At least this means they won’t be lighting the SRB’s in freezing temperatures!
Why don’t they set up a fan to blow away the leaking hydrogen? I’m sure they could make a pretty good finite element model of the air flow under different atmospheric and wind conditions and then validate it with some small scale wind tunnel tests., or use a big vacuum hose from a street cleaner, routing the fumes to a separator tank for eventual recycling?
Why don’t they set up a fan to blow away the leaking hydrogen?
Since it appears the hydrogen is leaking from ground connectors during the filling process, why front the $12.6 million for a cost-plus fan? Why not just wait for a gust of wind to disperse any excess hydrogen. Actually hydrogen, being lighter than air, will rise in the atmosphere, so you should only need to model air currents in a corridor between 150 to 500 ft. And make sure the Orion crew aren’t smoking cigarettes. Well anything for that matter. I’d be smoking something to ride that thing…
NASA: Normalizing Anomalys for Schedule Adherence
Speaking of which, I could hardly believe the spin from this NASA press release.
NASA concluded a wet dress rehearsal for the agency’s Artemis II test flight early Tuesday morning, successfully loading cryogenic propellant into the SLS (Space Launch System) tanks, sending a team out to the launch pad to closeout Orion, and safely draining the rocket.
Emphasis mine… Safety, capacity, flammability. Pick two…
Hydrogen vapor, just off the liquid, is heavier than air – it’s cold enough that it’s just a little denser. Plus it warms slowly, so a hydrogen cloud can sink fairly easily. Mixing with air and the possibility of sparks make using a fan nearby, or anything electrically driven, potentially unwise.
This was a factor in the first DC-X mishap in June 1994.
Yes of course you are right. I should have recalled the story from Ben Rich’s book about the CL-400, where they’d been storing liquid hydrogen in their Burbank facility until one day they had a bad leak and vapors were all over the floor of the tank facility… A bad day…
My favorite table (see page 134, sorry for the poor print quality of the repoduction) I like to show people that like to propose the “hydrogen economy” as a replacement for “fossil fuels”…
Darn, that means a detail I had in one of my hard SF stories is wrong. In a description of a Space Shuttle disaster (on-pad explosion), I had the hydrogen fumes rising.
Once they ignite they rise pretty quickly.
The fact that the vapor from liquid hydrogen boiloff is heavier than air turned out to be a headache for SLC-6 at Vandenberg during the planning for its use as a Shuttle launch pad. IIRC, the as built-duct would have trapped the escaping hydrogen, resulting in an explosive atmosphere. (They also had to add two new flame ducts for the SRBs, so it wasn’t like they didn’t have some work to do.) The problem must have been solved, though, because they did fly Delta IV off of SLC-6 beginning in 2006.
The problem must have been solved, though, because they did fly Delta IV off of SLC-6 beginning in 2006.
Well solved “good enough”. Because there are plenty of videos showing no explosions but the D-IVH getting toasted on the outside at launch.
I should mention that “we” (TRW Launch Services Organization) investigated SLC-6 as a launch site back in 1992, and became intimately familiar with the history and problems of the site. When Lockheed Missiles and Space stole all of our intellectual property and started marketing the “Lockheed Launch Vehicle”, they launched from SLC-6. In fact, their only two successful launches went from there. Both were rockets I had designed while at TRW.
This sub-thread made me go grab a copy of this book for Kindle on my iPad. The story is recounted in Chapter 8 “Blowing Up Burbank”. Turns out it was an intentional dump in response to a hangar fire! WTF?
“…and on that evening the cold hydrogen filled that hangar with a fog five feet thick… The firemen saw the fog and went running for their gas masks. Had they known we were playing around with around with liquid hydrogen so close to Burbank Airport, I’m sure they would have had my scalp, but they put out the fire in two minutes and went away.
…and just two sentences prior to this:
“What is inside?” the fire chief asked me.
“National security stuff. Can’t tell you,” I [Rich] replied.
I gotta say the story raises more questions than it answers!
they could make a pretty good finite element model of the air flow under different atmospheric and wind conditions and then validate it with some small scale wind tunnel tests.
Even if they could, they would demand so many (around a hundred) such demonstration tests to do that validation, but only after spending a few million building that model and a few more to validate the software does anything. That in a nutshell is why there are 3 years between SLS launches.
For the money to do all that, they could have practiced filling several tanks until they determined all the ways it leaks and rectified them, which is what SpaceX does. “oh, but did you see that tank collapse!” Yeah, and it was spectacular and a setback that only cost them a couple of months, not years.
And George, I know you know this and likely be facetious.
And George, I know you know this and likely be facetious.
Bingo!
Sure, fixing the leak would be one obvious approach, but it doesn’t seem like NASA pursued that path after Artemis I since Artemis II also leaks. But maybe it’s a totally new leak that was part of a leak upgrade program.
If they had some liquid hydrogen and some connectors, they could probably test things in between flights, but that would probably entail a whole bunch of expense and paperwork and approvals involving lots of departments, and they’re only going to launch the SLS a few times anyway, so why bother?
But really, one of my issues with SLS is that it’s obviously not the path forward, it’s going to get cancelled, and it’s not going to lead to anything. From most perspectives, it would be hard to maintain focus and motivation once personnel think of it as more of a stunt to launch some legacy hardware more out of a sense of nostalgia than as a bold step in an aggressive development path. It starts feeling like the world’s most expensive Youtube stunt instead of a vital step in building humanity’s pathway to the stars.
“subtle shade from Jared”
Nice! This is consistent with other comments that he has made. My hope is that, when Starship first transfer propellant that people will start speaking up about an alternate Artemis architecture that doesn’t require: ML2, SLS, Orion, or Gateway.
Impressed with some of the swag on display at the presser.
You know Valentines’ Day is coming up. You wouldn’t want to miss out on these or these!
OTOH maybe flowers and dinner out…
…but it is not the most economic path and certainly not the forever path.
Ahem…
Remember those humongous fans NASA used to blow away Shuttle hypergols after landing? Gee, I wonder what happened to those.
“The President’s National Space Policy envisions a Moon base, with repeated and affordable missions to the lunar environment. Along that journey, some functions that NASA has performed in the past and present may move to industry in the future, and that is when NASA recalibrates toward the near-impossible and undertakes the next grand endeavor.
Where Apollo ended at 17, Artemis will live on for decades as we explore and realize the economic and scientific potential of the lunar surface. It is where we will test hardware and operations, including resource manufacturing, nuclear power, and propulsion, the tools necessary to undertake human missions to Mars.”
Goodbye SLS.
They’ll build a Moon base using Artemis, over decades? So they plan to build it all using 2 SLS launches?
In the past, there were lots of articles and gaseous emanations from politicians about how SpaceX is the cause of delay in getting back to the moon.
Well maybe requiring WDR’s to be perfect will delay the next SLS launch so much that no one can say SpaceX is the gating factor any more.
Did not Artemis-I have the exact same leak in the same location?
From what I have read (between the lines) I believe you are correct sir!
NASA means never learning from past mistakes
Question:
Did Delta IV have these issues?
What about the New Glenn Upper Stages?
Those are both pretty big Non-Shuttle Hydrogen Rockets(NSHR). (SLS is a SHR)
So, how do they deal with their Hydrogen interfaces? And Arianne? And Centaur for that matter?