Sep 8, 2025

Congress and Trump may compromise on the SLS rocket by axing its costly upper stage "At $4 billion a launch, you don’t have a Moon program." | The upper part of the Space Launch System rocket and the Orion spacecraft flown on the Artemis I mission is shown here. Credit: Trevor Mahlmann The upper part of the Space Launch System rocket and the Orion spacecraft flown on the Artemis I mission is shown here. Credit: Trevor Mahlmann Text settings Minimize to nav There are myriad questions about how NASA's budget process will play out in the coming weeks, with the start of the new fiscal year on October 1 looming. For example, the Trump administration may seek to shut off dozens of science missions that are either already in space or in development. Although Congress has signaled a desire to keep these missions active, absent a confirmed budget, the White House has made plans to turn off the lights. Some answers may be forthcoming this week, as the House Appropriations Committee will take up the Commerce, Justice, and Science budget bill on Wednesday morning. However great uncertainty remains about whether there will be a budget passed by October 1 (unlikely), a continuing resolution, or a government shutdown. Behind the scenes, discussions are also taking place about NASA's Artemis Program in general and the future of the Space Launch System rocket specifically. $4 billion a launch is too much From the beginning, the second Trump administration has sought to cancel the costly, expendable rocket. Some officials wanted to end the rocket immediately,  but eventually the White House decided to push for cancellation after Artemis III. This seemed prudent because it allowed the United States the best possible chance to land humans back on the Moon before China got there, and then transition to a more affordable lunar program as quickly as possible. Congress, particularly US Sen. Ted. Cruz, R-Texas, was not amenable. And so, in supplemental funding as part of the "One Big Beautiful Bill," Cruz locked in billions of dollars to ensure that Artemis IV and Artemis V flew on the SLS rocket, with the promise of additional missions. Since the release of its budget proposal in May, which called for an end to the SLS rocket after Artemis III, the White House has largely been silent, offering no response to Congress. However that changed last week, when interim NASA Administrator Sean Duffy addressed the issue on a podcast hosted by one of the agency's public relations officials, Gary Jordan: Here is my one concern. If Artemis I, Artemis II, and Artemis III are all $4 billion a launch, $4 billion a launch. At $4 billion a launch, you don’t have a Moon program. It just, I don’t think that exists. We have to bring the price down. And so I have to think about and work with members of Congress. What does Artemis IV, V, and VI look like? But to spend that much money in thinking about what we have to do to have a sustained presence, I think becomes very, very challenging. And so what? What is the answer? I don’t know, but those are things that I think about, because you look at what the private sector has done for access to space. For the private sector, again, you can, you can have a satellite and get it into space for, you know, a million, little over a million dollars, like that was unheard of 20 years ago. What’s happening to drive the price down of these, of these vehicles. That’s what we have to think about, because the $4 billion figure just is too massive to think we can be sustainable at that number. In these comments Duffy clearly argues that the SLS rocket is unaffordable and that any lunar program built around it cannot be sustained for more than a few flags-and-footprints missions. Instead, he says, the agency should be taking advantage of commercial alternatives (which are being developed by SpaceX and Blue Origin). So is this an impasse? Possibly not, as sources say the White House and Congress may not be all that far apart on how to handle this. The solution involves canceling part of the SLS rocket now, but not all of it. Let’s make a deal The language in Cruz's supplement to the "One Big Beautiful Bill" says NASA must procure and operate the Space Launch System for Artemis IV and V missions but does not specify the configuration of the vehicle. NASA had been intending to upgrade the rocket with a new second stage, the Exploration Upper Stage, starting with Artemis IV. However this upgrade has already cost NASA billions of dollars and has necessitated construction of a launch tower that has vastly exceeded its original cost (now estimated at $2.7 billion) and is years behind schedule. For this reason the House Appropriations Bill calls for the space agency to "evaluate alternatives" to the Exploration Upper Stage. One of these, as Ars reported last year , is the Centaur V upper stage built by United Launch Alliance, which is already flight proven. Another option is a "short" version of the upper stage Blue Origin currently flies on its New Glenn rocket. Sources indicated that Blue has already begun work on a modified version of the stage that could fit within the shroud of the SLS rocket. This smaller version of the stage, like the Centaur V, would allow NASA to continue launching the SLS rocket using the existing launch tower in Florida. By canceling the Exploration Upper Stage and second launch tower, NASA could save more than $1 billion, annually, that could be applied to other aspects of the Artemis program to ensure its success both in the near and longer term. It would give the Trump administration the talking points it wants on making Artemis more affordable and allow Congress to continue flying its beloved SLS rocket for a few more missions. Finally, it would buy time to see whether SpaceX and Blue Origin can get their Starship and New Glenn rockets flying regularly and whether NASA can bring down the cost of a partly commercialized SLS rocket. At that point the future of NASA's deep space program, and the rockets it should use, will be clearer.