NASA awards ULA’s Centaur-5 upper stage for future SLS launches
NASA yesterday awarded ULA the contract for providing SLS its upper stage after the Artemis-3 mission using the Centaur-5 upper stage that was developed for the company’s Vulcan rocket.
In its procurement statement, NASA said its intention is to issue a sole source contract to ULA, meaning it’s the only upper stage being considered for this new iteration of the SLS rocket. An eight-page supporting document from NASA’s Marshall Space Flight Center (MSFC) in Huntsville, Alabama, was published to document the reasoning for its decision.
Among the stated reasons are the decades-long heritage of the RL10 engine, which has matured over time; the ability of the Centaur 5 to use the interfaces available on the Mobile Launcher 1 (ML1) along with the propulsion commodities of liquid oxygen and liquid hydrogen; and the experience of ULA’s teams working with NASA’s Exploration Ground Systems (EGS) at the Kennedy Space Center and elsewhere in the country.
They also noted that with the Centaur 3 upper stage achieving certification to launch humans as part of the Commercial Crew Program, there are a lot of common features with the Centaur 5.
The decision relieves NASA from wasting more money on the Mobile Launcher-2, which has been a disaster. The contractor Bechtel has gone over budget — from $383 million to $2.7 billion — and is so behind schedule it is still unclear now whether it will be ready by 2029, a decade after the contract was awarded.
It also relieves NASA of spending more money on its own upper stage, which has been as much a disaster, from Boeing.
Instead, this deal is an example of Isaacman doing the right thing. Rather than have NASA design and build its own upper stage, he is buying the product — almost literally off-the-shelf — from a commercial rocket company. He should expand this effort, and consider other private rockets, such as Falcon Heavy, to replace SLS itself.
Now Isaacman should consider suing Bechtel for fraud and incompetence, to try to get back some of the money it wasted.
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
NASA yesterday awarded ULA the contract for providing SLS its upper stage after the Artemis-3 mission using the Centaur-5 upper stage that was developed for the company’s Vulcan rocket.
In its procurement statement, NASA said its intention is to issue a sole source contract to ULA, meaning it’s the only upper stage being considered for this new iteration of the SLS rocket. An eight-page supporting document from NASA’s Marshall Space Flight Center (MSFC) in Huntsville, Alabama, was published to document the reasoning for its decision.
Among the stated reasons are the decades-long heritage of the RL10 engine, which has matured over time; the ability of the Centaur 5 to use the interfaces available on the Mobile Launcher 1 (ML1) along with the propulsion commodities of liquid oxygen and liquid hydrogen; and the experience of ULA’s teams working with NASA’s Exploration Ground Systems (EGS) at the Kennedy Space Center and elsewhere in the country.
They also noted that with the Centaur 3 upper stage achieving certification to launch humans as part of the Commercial Crew Program, there are a lot of common features with the Centaur 5.
The decision relieves NASA from wasting more money on the Mobile Launcher-2, which has been a disaster. The contractor Bechtel has gone over budget — from $383 million to $2.7 billion — and is so behind schedule it is still unclear now whether it will be ready by 2029, a decade after the contract was awarded.
It also relieves NASA of spending more money on its own upper stage, which has been as much a disaster, from Boeing.
Instead, this deal is an example of Isaacman doing the right thing. Rather than have NASA design and build its own upper stage, he is buying the product — almost literally off-the-shelf — from a commercial rocket company. He should expand this effort, and consider other private rockets, such as Falcon Heavy, to replace SLS itself.
Now Isaacman should consider suing Bechtel for fraud and incompetence, to try to get back some of the money it wasted.
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
But is it fixed-price or cost-plus? That’s what really matters.
There was a fascinating exchange on X the other day, where Isaacman jumped into a fray where SLS stans were thrashing Tom Mueller over his support for Isaacman’s decision — easy to miss, because Jared used his personal X account rather than his NASA one. Then they set upon Jared, insisting that it was a terrible idea to cancel EUS and the Mobile Launcher 2 when both were nearly ready. Isaacman had a harsh response:
I love that NASA has an engaged community that is passionate about our hardware. I will just say that those who believe ML-2 and EUS were “right around the corner” are mistaken. We can spend billions more and put the schedule at risk, or we can focus our resources and limited time on going to the Moon. The people have waited long enough for this grand return–industry knows that, political leadership knows that, and at NASA we certainly know that.
https://x.com/i/status/2029365672434909616
Even more interesting, this spurred discussion on one of the NASA subreddits on Reddit. A few regulars who have established some credibility as NASA or contractor employees amplified what Isaacman said. Bechtel may have been paid on almost all milestones on Mobile Launcher 2 construction, but in reality the thing is a mess, a long way from being ready for delivery, with numerous faults thanks to shoddy work by Bechtel. EUS is not much better off. Boeing’s test article is taking shape, but it’s going nowhere fast, as even one former Boeing employee who still supports EUS puts it:
“EUS is just as much of an uphill battle as anything else. Welds are new, you have to qualify the structure, you have a RCS system unrelated to Starliner (laugh or cry about it), and a new engine. There is barely anyone left that did weld qual for Corestage and no one on SLS who has worked with RCS or an RL-10.”
https://www.reddit.com/r/SpaceLaunchSystem/comments/1rmmihd/isaacman_addresses_the_claims_that_eus_ml2_are/
Yikes.
Richard M: More evidence of the bankruptcy at Boeing. And I repeat, NASA should consider legal action against Bechtel. But that’s in the real world. Such things are not done in DC, when it comes to fraud and incompetency that steals taxpayer money.
Perhaps SpaceX could finish that.
At some point, I see. Elon allowing hydrogen craft atop SH if not in SS itself, so a flex-fuel arrangement would be wise.
FH already has one shuttle pad.
If anything comes of New Armstrong, it needs the SLS pad.
Agreed in full, Bob.
“Perhaps SpaceX could finish that.”
SpaceX is literally building five (5) launch complexes with all associated ground systems for Starship right now, and is rebuilding SLC-6 at Vandenberg to launch Falcon 9 and Falcon Heavy. Even if they were willing to bid on it (and they aren’t), they have absolutely no workforce or resources to spare for more launch pad work — and NASA very much wants to see SpaceX get all those pads into operation as quickly as possible, for obvious reasons.
The organization which designs and builds your launch pad ought to be the same organization which designs and builds your rocket. That’s how every commercial launch provider in the U.S. is doing it now, and there’s a reason for that!
You know NASA has been spending like a.drunken sailor on all the SLS and acting like a Saturn Cargo Cult. For all this.money we could have had half a dozen Nautilus-X craft hanging out at EML-2.
Plus make another half dozen to keep Space Force happy to act as rescue patrol.
Instead we get a pile of junk that doesn’t work.
For those who say that how do we get Nautilus-X to orbit? That is BO and SX. Why will they succeed where NASA failed?
Capitalism in Space.
Starlink, Starlink Cellular, Starlink Datacenters, Amazon LEO and the boatloads of.cash generated from them.
Remember, Starship hardware-rich development is funded by those boatloads of cash.
Call Me Ishmael,
We don’t know the terms of the contract yet, because all that has been released is the justification for sole sourcing document; ULA has to submit a formal proposal before a contract can even be offered. But given how NASA itself describes the procurement (“This approach leverages current support infrastructure and will use, with relatively minor modifications, an existing ULA upper stage.”), to say nothing of the politics, I think I’d be surprised if it were not firm fixed cost.
(Firm fixed price FAR contracts are not bulletproof against program cost growth; Lunar Gateway HALO/PPE was procured on a fixed price contract, but NASA threw some major change orders at it, and those increased the price, as did the need to procure a new launch contract once they decided to do them in a single FH launch. But that seems less likely here, as there is very little to change about the Centaur V, a proven operational rocket stage currently in serial production. Cost risk will center on necessary changes to ground systems.)
P.S. Your screen name and the subject matter of this thread brings me to mind of one of my favorite quotes from Moby Dick: “There is all the difference in the world between paying and being paid.”
P.S. To clarify a little more on my last post: Just to be clear the contract for this isn’t issued yet. Rather, the justification for sole source has been approved and it now enters a 30 day inactive period to allow for challenges to be filed. After the 30 days is done they will rule on any challenges that were filed and then they will be allowed to begin negotiations with ULA over terms. The actual contract award is expected in October, though Jared seems to be in enough of a hurry that he might accelerate that a little.
EUS is just as much of an uphill battle as anything else. Welds are new, you have to qualify the structure, you have a RCS system unrelated to Starliner (laugh or cry about it), and a new engine. There is barely anyone left that did weld qual for Corestage and no one on SLS who has worked with RCS or an RL-10.”
——-
I see this as a problem across industry. Management really believes highly technical personnel are completely interchangable. They like to acquire talent but aren’t concerned so much about keeping it.
Richard M,
“Yikes” is right! Makes one understand Jared’s obsession with restoring in-house expertise at NASA even if it does not cause one to agree with how he seems intent on accomplishing that.
As for the Centaur 5’s designation as the SLS upper stage, that was pretty much inevitable given Jared’s rejiggering of Artemis. Only game in town, really.
Jeff Wright,
I think the only way any Starship pad is ever likely to be plumbed for LH2 is if SpaceX builds tanker Starships to carry the stuff. That might occur if some internal need arises for SpaceX to have a lot of LH2 transported to LEO or beyond or if some customer comes calling – with a suitable quantity of cash in-hand – who needs such a capability.
If Blue wants to stake a post-SLS claim to LC-39B it will probably have to outbid SpaceX. In addition to the five Starship launch complexes SpaceX should have operational by the end of next year, I think it will want still more if it can get clearance for them. One more at LC-39A on the side of the extant pad opposite where the currently-under-construction Starship launch complex is going in seems entirely likely. A matching pair of such facilities flanking the extant pad at LC-39B would be an obvious next step.
That wouldn’t, in theory, necessarily preclude Blue operating either New Glenn or a notional New Armstrong from the extant SLS pad, but as a practical matter the logistics probably wouldn’t work.
What does RCS mean?
Some of us are not as immersed in the history and language of spaceflight and NASA as others, so the generous use (overuse?) of acronyms is daunting.
Hi Dick,
“As for the Centaur 5’s designation as the SLS upper stage, that was pretty much inevitable given Jared’s rejiggering of Artemis. Only game in town, really.”
Well, that and the New Glenn upper stage (GS2), which as the notification discusses, NASA actually looked at. (According to Eric Berger last month, a GS2 presently costs Blue Origin $50 million to build, FWIW.) But the GS2 would be a bigger hassle in terms of ground system modifications than the Centaur V — though even it, too, would still be a better deal than the Exploration Upper Stage.
Hi Terry,
“What does RCS mean?”
RCS = Reaction Control System
RCS = Reaction Control System, usually implemented with thrusters.
Terry,
RCS is Reaction Control System. It is the thrusters (and related hardware) to steer the spacecraft.
People who read me regularly and pay close attention will notice that I avoid acronyms as much as possible, and if I do use them, I try to ALWAYS include at least once the full term. This used to be standard editorial practice in the past.
I prefer to write in English. I wish more people would try to do so.
I’m to blame, because I posted the comment that first introduced the “RCS” acronym.
I can only plead that it was a direct quote of a Reddit post, so I did not feel pressed to spell it out; but then I’ve caught myself typing “EUS” in more than one post here without ever spelling it out, too.
In the future, I will try to make a renewed effort to spell out any acronyms on at least the first use in a comment, even if it is a quote.
Robert Zimmerman,
I’ve always endeavored to do that full-wording-once thing too as I am also annoyed by use of undefined acronyms. I admit to getting a bit sloppy in that respect lately. I will try to do better in future. I will draw the line at defining ‘NASA’ in this way, however.
Jeff Wright,
If you’re reading this Jeff W., you might want to consider taking the oath too. You do the undefined acronym thing a lot and, to make it worse, many of the acronyms you use are quite obscure and/or antique.
Richard M,
I’m sure Jared did have his people look at the New Glenn 2nd stage (NG2) as a potential replacement for the Exploration Upper Stage (EUS). Blue would have insisted. I suspect, though, that that “look” didn’t take long. NG2 has some pretty obvious minuses anent Centaur 5 (C5) as a replacement for the Delta-IV-derived Interim Cryogenic Propulsion Stage (ICPS) used for Artemis 1 and scheduled to be used for Artemis 2 and 3 as well.
1. NG2 is way bigger than C5 in every dimension, especially diameter. Those conformal work platforms inside the Vertical Assembly Building (VAB) might need a bit of modification from their ICPS configuration to handle C5, but the two stages are pretty close to the same diameter – roughly 5 meters. Accommodating the 7-meter-diameter NG2 would involve major surgery on, or complete replacement of, at least one set of those work platforms. This would be both quite expensive and quite time-consuming.
2. NG2 is also way taller than C5. C5 can probably be fitted with adapter hardware to make it take up the same vertical distance on the Space Launch System (SLS) stack as ICPS, but there isn’t a prayer of doing that with NG2. That would mean raising up all of the VAB work platforms associated with both the European Service Module (ESM) and the Orion capsule itself. That would likely be an even more daunting job than would the modifications to handle NG2’s greater diameter. More expense and time added to the ledger and the schedule for Artemis.
3. NG2 is also way heavier than C5. Even with C5, there might be a need to beef up the conical adapter interstage structure that currently connects the SLS core stage to the ICPS as the C5 is also heavier than the ICPS, but not by nearly as much. This adapter would have to be extensively re-engineered in any case to accommodate NG2’s larger diameter. Yet more money and time.
4. The NG2 hardware for propellant, power and other umbilicals is not going to be a close match, either in placement or in configuration, to that currently used on the ICPS. As both ICPS and C5 have the same manufacturer, I suspect any differences between them in terms of pad support interfaces are either far smaller or non-existent.
5. The NG2 has an intrinsically much lower production cadence than the C5. The NG2’s structure/tankage is made of aluminum iso- or ortho-grid panels. These require enormous amounts of tedious machining. The C5, in contrast, is constructed almost entirely of stainless steel sheet stock. Despite the Centaur stage’s ancestry dating back to the early 1960s, its fabrication technology has a lot more in common with SpaceX’s Falcon 9 or Starship than with most other rocket stages. This allows for a much higher production cadence than NG2’s.
This matters because Blue is going to have a lot of call on NG2 production capacity for all of the things New Glenn (NG) is going to have to do while the Artemis program proceeds. That includes, at a minimum, lots of launches for Amazon Leo. Even for Blue’s own contributions to Artemis, apart from any notional SLS upper stage replacement for ICPS, it is rumored that its short-term lander architecture, based on the Blue Moon Mk1 lander – which was not originally intended to carry crew – will still involve at least three New Glenn launches – one for the lander and two more for a pair of transfer stages needed to get the lander to the Moon and back to Orion. United Launch Alliance (ULA), which made the ICPSes and is now making the C5, will have need for a lot of C5s for its own Amazon Leo deployment contract as well as work for the War Department using its Vulcan launcher. But the C5 is just a lot more buildable at scale so ULA can easily handle a need for one or two C5s a year for Artemis SLS missions.
The NG2-or-C5 decision was pretty much a no-brainer.
Richard M: Note too that I rarely use “reaction control system.” That’s engineering jargon. I always try to refer to these as attitude thrusters or some variation. Plain English, and it helps the reader.
This applies to a lot of this discussion. Notice how I rarely use EUS or its full name. It is “SLS’s upgraded larger upper stage” or some variation thereof.
This policy applies across the board. I always try to replace jargon with plain English terms that always worked before engineers and bureaucrats invented new terms to make them sound smart.
Dick Eagleson March 8, 2026 at 8:12 pm reply to Richard M:
I find it interesting that your list of comparisons all speak to economics and not tech or science.
This is a good thing. It may possibly mean that the Isaacman/NASA focus is turning towards economics and efficiency.
Hello Saville,
Always worth remembering that Jared’s previous career has been mostly as an entrepreneur, not a technocrat or politician!
Saville,
That’s because there is no science at issue and not much tech either. We have two upper rocket stages, both of which are now in service. Tech issues are limited to those engineering considerations required to insert either stage into the extant Space Launch System (SLS) stack. Economics and efficiency come in because the costs of the engineering changes needed to insert one stage, Blue Origin’s New Glenn 2 (NG2) would be vastly greater than those required to insert the other – ULA’s Centaur 5 (C5).
Mr. Lender is correct that deciding matters based on costs and schedules is very much in Administrator Isaacman’s wheelhouse. For someone accustomed to the business-world attitude toward such matters – costs are to be minimized consistent with achieving other goals – NASA is an entire orchard of low-hanging fruit.
Richard M wrote: “…. Then they set upon Jared, insisting that it was a terrible idea to cancel EUS and the Mobile Launcher 2 when both were nearly ready.”
That sounds like the sunk cost fallacy in action. ‘We spent so much already that we should spend what it takes to finish it.’
____________
Jeff Wright wrote: “Perhaps SpaceX could finish that.”
In addition to Richard M’s wise words, SpaceX does things differently and would not be a good choice to complete what Bechtel has started. It would be best if SpaceX started from scratch, which would be a huge diversion from their mission, leading right back into what Richard M already said.
Thinking that SpaceX can and should solve all the world’s problems is not a good idea. Not only should the company not be distracted from its mission and its focus, it is barely an expert on what it does already, considering that — as we watch — it is inventing much of what it does. It is still on a steep learning curve for several of its missions.
____________
Saville,
One of the reasons that NASA is not a powerhouse space operator is that it puts technology and science ahead of economics. Rather than work on doing something economically, it ponders how to get the most technology advancements and science from individual projects. As Richard M noted earlier, NASA tends to make major changes that increase the costs and slips the schedules, because they all too often decide that it is more important to do something differently than to do it efficiently, and the result is often that less science is done in the long run.
Jared Isaacman comes from the real world, where efficiency is king, and that is what he is bringing to NASA.
Edward: I wish more people would consider not just what we’ve already spent monetarily, but also consider both the opportunity costs (in terms of both skilled workers and money) going forward. The total dry mass each SLS will launch is minimal, and in a world of much cheaper launch that is available now, there are numerous ways to use the thousands of NASA employees for greater benefit than launching an obsolescent rocket every few years. So many people set their egos ahead of what is worthwhile, and do so without a scrap of concern for how they’re using other people’s money.
Hello Edward,
“That sounds like the sunk cost fallacy in action.”
It really does, doesn’t it?
All they’re left with is the mantra that the new plan won’t be any faster than the old plan. But the idea that Boeing was going to have the Exploration Upper Stage ready in 2028 (pinky promise!) or any date remotely close to it, just does not pass the laugh test.
Nate P,
“I wish more people would consider not just what we’ve already spent monetarily, but also consider both the opportunity costs ”
Bastiat wrote about this kind of loss in his essay, “That Which Is Seen, and That Which Is Not Seen.” If a shopkeeper’s window is broken, then the glazier makes money replacing it and is better off for the work, but the shopkeeper is not any better off. That seems like a good thing, making a job where there wouldn’t have been one otherwise. To go a little more extreme then shouldn’t we break a lot of windows to give the glazier even more work, or even more extreme, shouldn’t we burn down Paris so that many people are employed rebuilding the city? If the window hadn’t been broken, then the shopkeeper could have employed the cobbler to renew his worn shoes, in which case the shopkeeper and the cobbler both are better off.
If the James Webb Space Telescope hadn’t gone twenty times over budget, then we could have had nineteen more space telescopes and the science that would have gone along with them. If the Constellation Project hadn’t been cancelled or if SLS had stayed on schedule (and been better designed), then we could have had a lunar base by now for the same cost as we spent on SLS so far.
Indeed, because we stopped going to the Moon and expanding our abilities in space, our Artemis program is now trying to get us back to where we were in space in 1970, rebuilding Apollo in a way similar to Bastiat’s example of rebuilding Paris: much spending, plenty of jobs, little progress.
If the government had treated NASA as a productivity center rather than a jobs program, then the agency would not have been adrift, a decade ago, and our tax money would not have been squandered along with the talents, skills, and knowledge of NASA’s workforce. In essence, our government space program did not make us much better off in space than we were half a century ago. Considering the current NASA budget, half a century of such spending that gained us so little advancement is a large amount of lost opportunity cost.
Thank you to everyone who helped define “RCS” for me. Looks like I’m not the only one who isn’t a fan of acronyms.
Edward: yes. For a vivid metaphor, it’s like a car stuck in a rut revving its engine. The wheels are spinning, the engine is noisy, but the car is going nowhere. Maybe rocking back and forth a bit, but remaining in the rut. And some people are pleased by that!