Fuel leaks cause Artemis-2 dress rehearsal countdown to terminate at T-5:15, several minutes early
Two hydrogen fuel leaks during today’s Artemis-2 dress rehearsal countdown forced an early termination of the count as well as the cancellation of a second practice countdown.
The Artemis II wet dress rehearsal countdown was terminated at the T-5:15 minute mark due to a liquid hydrogen leak at the interface of the tail service mast umbilical, which had experienced high concentrations of liquid hydrogen earlier in the countdown, as well. The launch control team is working to ensure the SLS (Space Launch System) rocket is in a safe configuration and begin draining its tanks.
An earlier leak of hydrogen in the count forced a hold and a recycling of the count, though it did not stop the rehearsal.
The initial plan had been to do two terminal counts. First they would run the countdown down to T-33 seconds, hold for a few minutes, then recycle back to T-10 minutes and do it again. Because of that first leak delay the launch director canceled the second count. And because of the second leak they were unable to run that one count all the way to T-33 seconds.
The wise action would be for NASA to review their data, figure out what caused the leaks, correct it, and then do another dress rehearsal countdown. This being NASA, do not be surprised if they review the data, figure out what caused the leaks, and decide they can go ahead with the launch on February 8, 2026.
Why not? They are already launching this manned 10-day mission around the Moon with an untested life support system and a questionable heat shield. Might as well try a launch when you haven’t worked out all the fueling kinks.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Two hydrogen fuel leaks during today’s Artemis-2 dress rehearsal countdown forced an early termination of the count as well as the cancellation of a second practice countdown.
The Artemis II wet dress rehearsal countdown was terminated at the T-5:15 minute mark due to a liquid hydrogen leak at the interface of the tail service mast umbilical, which had experienced high concentrations of liquid hydrogen earlier in the countdown, as well. The launch control team is working to ensure the SLS (Space Launch System) rocket is in a safe configuration and begin draining its tanks.
An earlier leak of hydrogen in the count forced a hold and a recycling of the count, though it did not stop the rehearsal.
The initial plan had been to do two terminal counts. First they would run the countdown down to T-33 seconds, hold for a few minutes, then recycle back to T-10 minutes and do it again. Because of that first leak delay the launch director canceled the second count. And because of the second leak they were unable to run that one count all the way to T-33 seconds.
The wise action would be for NASA to review their data, figure out what caused the leaks, correct it, and then do another dress rehearsal countdown. This being NASA, do not be surprised if they review the data, figure out what caused the leaks, and decide they can go ahead with the launch on February 8, 2026.
Why not? They are already launching this manned 10-day mission around the Moon with an untested life support system and a questionable heat shield. Might as well try a launch when you haven’t worked out all the fueling kinks.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Isaacman fired off a new announcement on X that NASA has decided to move back the launch to the March launch windows.
https://x.com/i/status/2018578937115271660
Color me shocked that this finicky leak prone legacy hydrolox launcher has been stymied by finicky hydrogen leaks once again…and that Orion had close out issues, too.
Still, Isaacman continues his pattern of greater public communication and transparency for the agency, and that’s not nothing.
My guess is the SLS will be plagued by leaks for the rest of its life, and that it will never launch when originally scheduled. They just won’t get enough experience to make it otherwise.
Hello Nate,
All you have to do is to look at the Shuttle’s track record with hydrogen leak-based launch delays!
This problem was baked into SLS from Day One when they decided to use Shuttle propulsion systems for the architecture.
Isaacman: “With more than three years between SLS launches, we fully anticipated encountering challenges. ”
One would think that a 3 year gap between flights would condemn the system to the junk pile. SpaceX has demonstrated what a high cadence does for you.
This problem is intrinsic to liquid hydrogen — the H2 molecules are just too small for seals to be reliable in ordinary use.
Saville,
Indeed. Eric Berger made a related point this morning on X:
“There are many, many problems with the SLS rocket architecture, but one of the biggest is its extremely low flight rate, which makes every fueling and launch an experimental rather than operational procedure.”
https://x.com/i/status/2018673438613762183
SpaceX passed the experimental point with Falcon 9 and Dragon a long, long time ago. Even the Shuttle reached a certain level of competent efficiency with its launch systems and teams….which is why, as Wayne Hale once noted, Shuttle managers got nervous any time the Shuttle launch rate dropped below 4 times per year.
SLS will never get close to that frequency of launch even when it reaches its supposed operational cadence of once per year. Boeing supposedly has the theoretical capability to crank out a core stage every 8 months if they reach full staffing at Michoud. But even if they could, you would also need a pair of SRB’s, an Exploration Upper Stage, an interstage, and an Orion CSM ready every 8 months, too. (Let us not even mention actual mission hardware.) How much do you think *that* would cost? And how long would it take NASA, Boeing, Lockheed, and Airbus to reach that tempo?
Richard M: I wish SLS backers would, just once, acknowledge the formidable obstacles to their dreams, which are, as you say, baked in to the vehicle, rather than blaming detractors like ourselves for them. A single, honest acknowledgement of the issues that doesn’t equivocate, dodge, obfuscate, or otherwise minimize things.
Hello Nate,
Unfortunately, arguing with most of ’em is like talking to a brick wall, as I can say from personal experience. The objections are either *interested* (i.e., they either work on the program at NASA or a contractor) or from some irrational impulse, usually a disdain for Elon Musk or for any non-governmental entity doing human spaceflight, full stop. Or, quite often, both at the same time.
SLS criticisms are also “interested” as it ” I will fund more of my projects by killing MSFCs”
Richard M: that’s my experience too. It comes off as a grubby pursuit of power or money.
Jeff Wright: the SLS is worth killing even if NASA completely loses the taxpayer dollars it provided to the agency, and all of that money was left in the citizenry’s pockets. Yes, in an ideal world it would be transferred to more deserving programs, but that isn’t how Congress works. And there’s no law saying that Marshall cannot work on other programs (as indeed they already are). As big a blow as it is to your ego, the center has the skill to work on programs aside from obsolescent rockets.
“I will fund more of my projects by killing MSFCs.”
The difficulty is that not only are NASA budget dollars limited, but so too are top aerospace engineering and technical skills. There’s only so much of each of these things to go around. And I would rather have those scarce dollars, scarce engineers, and scarce technicians directed to the vehicles and systems of greatest value to both NASA and the nation. There was a moment in the 1960’s and 70’s when a government program (Apollo) really did make MSFC and its prime contractors the place where you could find all that. But that is just not the case any longer. Today , if you are a brilliant young aerospace engineering graduate, you are far more likely to make a substantive contribution to America’s future in space if you go off to work for SpaceX, Rocket Lab, or Impulse Space than if you go to MSFC, I’m afraid.
I think there’s a role for MSFC in the kind of future I am talking about, as Nate suggests. And it is something far closer to the original NACA charter. There’s value in primary research into propulsion and other technologies that private industry is not in a position to pursue. MSFC could do that. And it would be a far better way to use the center than building ferociously obsolescent and obscenely expensive launch vehicles.
How do you build a rocket & there are fuel leaks? Maybe get some real mechanics that actually know what their doing.
Since there’s been some discussion in the other threads of Jared Isaacman’s performance, and discussion in *this* thread of SLS’s woeful launch rate, it is worth noting that Isaacman just quote tweeted Eric Berger’s post with a remarkable post that’s getting a lot of eyeballs (100K plus already) on it. I think it is worth posting here in full:
Link: https://x.com/NASAAdmin/status/2018735401876557934
I suppose it has some value that a NASA Administrator is willing to respond directly to this (long-time) criticism of SLS like this, and basically concede its substance. It would be better if this manifested as *cancellation*, or in Jared’s case, at least in a more aggressive advocacy for same in the halls of Congress and the White House. How you actually could make that happen is the subject for a much longer discussion. Great things require great men, but they also usually require the right moment.
Argh. I really screwed up the tags on that last one by accidentally hitting “Post Comment” before I was done. Bob is free to fix it, but if not, I think y’all can tell where Jared’s post began and where it ended. I think you can also figure out where his most spicy passages are.
Richard M: Tags fixed.
I suspect the bit about economics and not lasting forever have more than a few people trembling in frustration. My guess has long been that the SLS will fly at least five flights, but no more than ten, and nothing has happened to make me think it will last any longer. The rocket simply cannot be improved to the point where it would make sense to fly it for decades. Maybe if it were the 70s again and nothing else was available, but we have plenty of access now, and we’ll have more as Artemis ramps up. The SLS gives us nothing unique.
Nate P and Richard M: My endless compulsion to see the future is ringing bells in my head. I see Isaacman’s statement and the history of SLS in past wet dress rehearsals as setting the stage for some very interesting politics. Essay to follow.
1. Thanks for the fix, Bob!
2. As regards SLS wet dress rehearsals and their….uh, troubled history, there were some interesting questions and answers about that at the NASA press conference today. Ellie in Space captured one of them, which you can watch at the link on X (it’s only 3:44 in length), when Marcia Dunn of the Associated Press asked, basically: Just explain how the heck you can still be having the same problem with hydrogen leaks three years later after Artemis I?
https://x.com/Ellieinspace/status/2018765895355777094
John Honeycutt, Chair, Artemis II Mission Management Team, stumbles around trying to answer it in some detail, but it becomes obvious that his answer amounts to . . . well, basically, we’re kinda stuck with this risk as a result of the architecture design forced on us to use this legacy propulsion system, and we just try our best to mitigate and minimize it as best we can.
By the way, this clip also makes clear that NASA has not decided on a final decision on a rollback of the stack to the VAB, but they do add that right now they have sufficient access to the rocket that it’s *possible* that they may be able to do the fixes they need before trying again next month. Or at least, that is what they think at the moment.
For those with a passion for this, or just a lot of time to kill, you can watch the full presser here:
https://www.livetube.tv/news/video-live-nasa-holds-news-conference-after-artemis-ii-dress-rehearsal
P.S. This is why you wish NASA would do more press conferences, like they used to, once upon a time. Because *some* of these reporters on the space beat really do ask some worthwhile questions when they get the chance, and you can hear a few such instances in this presser. And it’s worth seeing NASA management’s feet held to the fire trying to answer them on the record.
Richard M and all: Refresh your browsers to see my essay on this subject.
P.S. I laughed out loud at Rand Simberg’s comment on that Jared tweet: “Notice the subtle shade from Jared: ““With more than three years between SLS [Space Launch System] launches, we fully anticipated encountering challenges.””
Yes, some of Jared’s criticisms of SLS were more subtle than others.
Hello Bob,
Will do!
Bob: “How do you build a rocket & there are fuel leaks? Maybe get some real mechanics that actually know what their doing.”
This is what I was getting at earlier. LH2 molecules are so small that unless all joints and seals are mathematically perfect, there will be leaks. Leaks can be found and fixed with meticulous launch preparation, but LH2 intrinsically is not conducive to reliability. If you want a rocket that can launch on a reliable schedule, don’t use LH2.
LH2 is going to leak at every single joint in the system. All you can do is try to lessen it.
The quick connects are always going to be the biggest leak points. They always have on every launch.
I might not like the SLS but I am not going to complain about this problem this time.
I do think that NASA’s cadence leads to everything they do being experimental. They are always doing something for the first time. Then when they are doing it more than once, the time between iterations leads to huge personnel changes. which leads to those team members doing something for the first time.
And this does not take into account all the minor changes from version 1 to version 2.