SLS Artemis IV progress

[pochimax]

https://www.nasa.gov/centers-and-facilities/stennis/preparation-for-artemis-iv-testing/

NASA Marks Milestone in Preparation for Artemis IV Testing
Feb 11, 2026

Water flowing out. Data flowing in.

A water system activation at the Thad Cochran Test Stand (B-2) on Jan. 30 at NASA’s Stennis Space Center near Bay St. Louis, Mississippi, helped capture critical data to support testing a new SLS (Space Launch System) stage expected to fly on the Artemis IV mission.

The activation milestone tested new cooling systems that were added for the future Green Run test series of NASA’s exploration upper stage (EUS). The more powerful upper stage is a four-engine liquid hydrogen/liquid oxygen in-space stage for the evolved Block 1B version of SLS.

For Green Run, teams at NASA Stennis will activate and test all systems to ensure the stage is ready to fly. It will culminate with a hot fire of the stage’s four RL10 engines, just as during an actual mission.

As part of the test stand modification, crews have added water-cooled diffusers to act as a heat shield to manage the super-hot exhaust from all four RL10 engines; water-cooled fairings to direct engine exhaust to align with the diffuser walls; and a purge ring that supplies cooling water and gaseous nitrogen to protect a flexible seal that allows the engines to move, or gimbal, during testing.

These three systems all were integrated by the NASA Stennis team with the existing flame deflector and acoustic suppression equipment used during previous core stage testing for NASA’s SLS rocket ahead of the successful Artemis I launch.

The exercise also pushed the high pressure industrial water system to maximum capacity. While a typical RS-25 engine test at NASA Stennis runs a subset of the 10 diesel pumps and one electric pump, testing the exploration upper stage will require all eleven pumps running simultaneously.

The 14-million gallons of water used during the exercise on Jan. 30 was recycled throughout the test complex. A 66-million-gallon reservoir feeds water to the test stand through an underground 96-inch diameter pipe, with water distributed to various cooling components. The water ultimately flows into the flame deflector, then through a concrete flume to the stand’s catch pond. When the catch pond fills up, the excess water drains back to the canal through a drainage ditch, ready to be recycled for future use.

“We will use the data gathered to set the final timing of when valves are cycled, determine our redline pressures, and select the operating pressure,” said Nick Nugent, NASA Stennis project engineer. “This exercise also put the water system under a full load prior to the final stress test. It is always good to give the system a good shake down run prior.”

[Herb Schaltegger]

So in light of the Administrator’s announcement today regarding rescoping of the Artemis project, anyone have insight into what was meant about “standardizing” the vehicle second stage configuration for Artemis IV and going forward?

[StraumliBlight]

So in light of the Administrator’s announcement today regarding rescoping of the Artemis project, anyone have insight into what was meant about “standardizing” the vehicle second stage configuration for Artemis IV and going forward?

Ars Technica: NASA shakes up its Artemis program to speed up lunar return [Feb 27]

For the Artemis IV lunar landing mission, NASA also will need to human-rate a new upper stage for the SLS rocket. The vehicle currently uses a modified Delta IV upper stage manufactured by United Launch Alliance. But that rocket production line is closed, and NASA only has two more of these stages. With the cancellation of the Exploration Upper Stage, NASA will now procure a new stage commercially. NASA officials only said they will seek a “standardized” upper stage. As Ars has previously reported, the most likely replacement would be the Centaur V upper stage currently flying on Vulcan rockets.

Would New Glenn 9x4's second stage be a possible candidate?

Powered by four BE-3U engines, 9x4’s second stage carries 70 metric tons to low Earth orbit, 14 metric tons to Geostationary Orbit Direct, and 20 metric tons to Trans Lunar Injection. The second stage engines generate over 800,000 lbf thrust (3,558 kN), more than 100% of New Glenn 7x2 configuration.

[Coastal Ron]

So in light of the Administrator’s announcement today regarding rescoping of the Artemis project, anyone have insight into what was meant about “standardizing” the vehicle second stage configuration for Artemis IV and going forward?

My guess is that it is their way of saying that whatever upper stage they fly on Artemis IV, will be the same from thereon out.

What a concept, a rocket that doesn't change configuration after each launch... 

[Herb Schaltegger]

So in light of the Administrator’s announcement today regarding rescoping of the Artemis project, anyone have insight into what was meant about “standardizing” the vehicle second stage configuration for Artemis IV and going forward?

My guess is that it is their way of saying that whatever upper stage they fly on Artemis IV, will be the same from thereon out.

What a concept, a rocket that doesn't change configuration after each launch... 

Well, sure. I am just wondering/fishing for info about notional configurations for that upper stage. Some asked in the presser about hydrolox and Isaacman deflected the issue. So I wonder if they’re looking at potential methalox configurations as well. Not sure they really have a lot of options for a stage that would be needed in a 24 - 36 month timelines aside from something from Blue, to be honest. Far too late to dig J-2X out of storage for a large hydrolox stage.

[DaveS]

So in light of the Administrator’s announcement today regarding rescoping of the Artemis project, anyone have insight into what was meant about “standardizing” the vehicle second stage configuration for Artemis IV and going forward?

My guess is that it is their way of saying that whatever upper stage they fly on Artemis IV, will be the same from thereon out.

What a concept, a rocket that doesn't change configuration after each launch... 

That was always the plan; hence why the ICPS is called the Interim Cryogenic Propulsion Stage. It was always going to be replaced once the real upper stage was ready. Same thing with the SRBs once the shuttle inventory was gone.

[DanClemmensen]

So in light of the Administrator’s announcement today regarding rescoping of the Artemis project, anyone have insight into what was meant about “standardizing” the vehicle second stage configuration for Artemis IV and going forward?

My guess is that it is their way of saying that whatever upper stage they fly on Artemis IV, will be the same from thereon out.

What a concept, a rocket that doesn't change configuration after each launch... 

Well, sure. I am just wondering/fishing for info about notional configurations for that upper stage. Some asked in the presser about hydrolox and Isaacman deflected the issue. So I wonder if they’re looking at potential methalox configurations as well. Not sure they really have a lot of options for a stage that would be needed in a 24 - 36 month timelines aside from something from Blue, to be honest. Far too late to dig J-2X out of storage for a large hydrolox stage.

ULA builds Centaur V for Vulcan. Centaur V shares a lot of ancestry with ICPS, which was built by ULA or its parents. I don't know if ULA could build More ICPSs, (probably not), but they likely could build a Centaur V variant that can do the job. With sufficiently high commonality, this would reduce the unit cost.

[Tywin]

So in light of the Administrator’s announcement today regarding rescoping of the Artemis project, anyone have insight into what was meant about “standardizing” the vehicle second stage configuration for Artemis IV and going forward?

My guess is that it is their way of saying that whatever upper stage they fly on Artemis IV, will be the same from thereon out.

What a concept, a rocket that doesn't change configuration after each launch... 

Well, sure. I am just wondering/fishing for info about notional configurations for that upper stage. Some asked in the presser about hydrolox and Isaacman deflected the issue. So I wonder if they’re looking at potential methalox configurations as well. Not sure they really have a lot of options for a stage that would be needed in a 24 - 36 month timelines aside from something from Blue, to be honest. Far too late to dig J-2X out of storage for a large hydrolox stage.

I like the NG second stage with 4 BE-3U...

[lrk]

I wonder how this affects the Gateway modules that were supposed to fly on EUS, starting with Artemis-4.  Centaur-V would have more performance than ICPS, but still less than EUS. 

[Kasponaut]

So in light of the Administrator’s announcement today regarding rescoping of the Artemis project, anyone have insight into what was meant about “standardizing” the vehicle second stage configuration for Artemis IV and going forward?

My guess is that it is their way of saying that whatever upper stage they fly on Artemis IV, will be the same from thereon out.

What a concept, a rocket that doesn't change configuration after each launch... 

Well, sure. I am just wondering/fishing for info about notional configurations for that upper stage. Some asked in the presser about hydrolox and Isaacman deflected the issue. So I wonder if they’re looking at potential methalox configurations as well. Not sure they really have a lot of options for a stage that would be needed in a 24 - 36 month timelines aside from something from Blue, to be honest. Far too late to dig J-2X out of storage for a large hydrolox stage.

ULA builds Centaur V for Vulcan. Centaur V shares a lot of ancestry with ICPS, which was built by ULA or its parents. I don't know if ULA could build More ICPSs, (probably not), but they likely could build a Centaur V variant that can do the job. With sufficiently high commonality, this would reduce the unit cost.

If you look at the new NASA infographic it looks like a Centaur 5 on top of SLS.

Center-bottom left side of the infographic.

https://www.nasa.gov/wp-content/uploads/2026/02/artemis-update-graphic.png

[StraumliBlight]

https://www.nasa.gov/wp-content/uploads/2026/02/artemis-update-graphic.png

Higher resolution version.

[sstli2]

I wonder how this affects the Gateway modules that were supposed to fly on EUS, starting with Artemis-4.  Centaur-V would have more performance than ICPS, but still less than EUS.

When asked, they dodged the question today, but I think they really want to kill Gateway and simply couldn't because it was written into the budget. They could sneak through killing EUS/Block 1B because SLS still exists in some form, but couldn't kill Gateway without Congress.

Thus, I think the most likely answer is that at some point, they will get their wish - and it won't matter.

[Kasponaut]

https://www.nasa.gov/wp-content/uploads/2026/02/artemis-update-graphic.png

Higher resolution version.

Great! Thanks. Now it looks even more like Centaur 5 on top.

[Brovane]

So in light of the Administrator’s announcement today regarding rescoping of the Artemis project, anyone have insight into what was meant about “standardizing” the vehicle second stage configuration for Artemis IV and going forward?

My guess is that it is their way of saying that whatever upper stage they fly on Artemis IV, will be the same from thereon out.

What a concept, a rocket that doesn't change configuration after each launch... 

Well, sure. I am just wondering/fishing for info about notional configurations for that upper stage. Some asked in the presser about hydrolox and Isaacman deflected the issue. So I wonder if they’re looking at potential methalox configurations as well. Not sure they really have a lot of options for a stage that would be needed in a 24 - 36 month timelines aside from something from Blue, to be honest. Far too late to dig J-2X out of storage for a large hydrolox stage.

ULA builds Centaur V for Vulcan. Centaur V shares a lot of ancestry with ICPS, which was built by ULA or its parents. I don't know if ULA could build More ICPSs, (probably not), but they likely could build a Centaur V variant that can do the job. With sufficiently high commonality, this would reduce the unit cost.

Is that even possible to have a new upper stage(Like the Centaur V) ready and certified for SLS by 2028? 

[DanClemmensen]

So in light of the Administrator’s announcement today regarding rescoping of the Artemis project, anyone have insight into what was meant about “standardizing” the vehicle second stage configuration for Artemis IV and going forward?

My guess is that it is their way of saying that whatever upper stage they fly on Artemis IV, will be the same from thereon out.

What a concept, a rocket that doesn't change configuration after each launch... 

Well, sure. I am just wondering/fishing for info about notional configurations for that upper stage. Some asked in the presser about hydrolox and Isaacman deflected the issue. So I wonder if they’re looking at potential methalox configurations as well. Not sure they really have a lot of options for a stage that would be needed in a 24 - 36 month timelines aside from something from Blue, to be honest. Far too late to dig J-2X out of storage for a large hydrolox stage.

ULA builds Centaur V for Vulcan. Centaur V shares a lot of ancestry with ICPS, which was built by ULA or its parents. I don't know if ULA could build More ICPSs, (probably not), but they likely could build a Centaur V variant that can do the job. With sufficiently high commonality, this would reduce the unit cost.

Is that even possible to have a new upper stage(Like the Centaur V) ready and certified for SLS by 2028?

I have no clue. What goes into "certification"? Centaur V has high commonality with ICPS at some level, and there is a chance that Centaur V will have flown more often than ICPS by the time it is needed, since Vulcan should(?!) return to flight by November 2026 and "should" quickly reach a cadence of 20/yr or better. I realize that for certification Centaur-on-Vulcan is not the same as Centaur-on-SLS, but surely it's better than the projected ICPS or EUS flight history.

[Brovane]

So in light of the Administrator’s announcement today regarding rescoping of the Artemis project, anyone have insight into what was meant about “standardizing” the vehicle second stage configuration for Artemis IV and going forward?

My guess is that it is their way of saying that whatever upper stage they fly on Artemis IV, will be the same from thereon out.

What a concept, a rocket that doesn't change configuration after each launch... 

Well, sure. I am just wondering/fishing for info about notional configurations for that upper stage. Some asked in the presser about hydrolox and Isaacman deflected the issue. So I wonder if they’re looking at potential methalox configurations as well. Not sure they really have a lot of options for a stage that would be needed in a 24 - 36 month timelines aside from something from Blue, to be honest. Far too late to dig J-2X out of storage for a large hydrolox stage.

ULA builds Centaur V for Vulcan. Centaur V shares a lot of ancestry with ICPS, which was built by ULA or its parents. I don't know if ULA could build More ICPSs, (probably not), but they likely could build a Centaur V variant that can do the job. With sufficiently high commonality, this would reduce the unit cost.

Is that even possible to have a new upper stage(Like the Centaur V) ready and certified for SLS by 2028?

I have no clue. What goes into "certification"? Centaur V has high commonality with ICPS at some level, and there is a chance that Centaur V will have flown more often than ICPS by the time it is needed, since Vulcan should(?!) return to flight by November 2026 and "should" quickly reach a cadence of 20/yr or better. I realize that for certification Centaur-on-Vulcan is not the same as Centaur-on-SLS, but surely it's better than the projected ICPS or EUS flight history.

Thank you

I was just wondering because I had someone call me engineering illiterate for suggesting that the Centaur V since it has already flown and shares commonality with the ICPS that it would have a more rapid pace of development than EUS for flight. 

[sdsds]

To what extent can production of CS-4 be accelerated by removing the requirement to produce EUS-1 at the same time and using much of the same tooling and workforce?

[pochimax]

To what extent can production of CS-4 be accelerated by removing the requirement to produce EUS-1 at the same time and using much of the same tooling and workforce?

NASA could immediately begin welding the Artemis 4 LOX tank instead of hardware for the EUS, for example.

In fact, the credibility of the new schedule depends, among other things, on whether we actually see this work being done in Michoud now or shortly thereafter.

If Boeing and NASA have to wait until the new fiscal year of 2027, then the LOX tank would be welded by the end of this year in the VAC, as planned, and I don't see how the Artemis 4 SLS launch could be accelerated if that was the case.

[AndrewM]

Slide 14 from NASA's Ignition - Returning to the Moon presentation published March 26th was focused on Artemis IVs progress while slide 15 introduced the new upper stage.

[Hadley Delta]

There's been a lot of talk about how rugged the south pole is. I wonder if there's a case for making the first landing at a safer site in an Apollo 11-style plain area rather than going for the pinpoint Apollo 15 or 17 at the first try.