Major Artemis Shift Leaves Questions About SLS, Gateway Future

In a major announcement Friday, 27 February, NASA announced a considerable reworking of the Artemis Program architecture. The new architecture calls for accelerating the timeline for Artemis III to mid-2027, and critically, down-scoping it from a lunar landing to a low-Earth orbit mission to evaluate one or both of the commercial lunar lander vehicles with humans aboard. Such a mission would be similar to the Apollo 9 mission in early 1969, which laid the groundwork for the successful Apollo 11 lunar landing months later. To accommodate such a change and provide for an accelerated flight rate, though, the design of the SLS rocket will be significantly reworked. 

The primary rationale given for the change by NASA Administrator Jared Isaacman is to accelerate the flight cadence of the SLS rocket and Orion spacecraft that will ferry astronauts between the Earth and the Moon on lunar landing missions. With Artemis II currently experiencing months-long launch delays of a remarkably similar nature to the ones that plagued the Artemis I mission, scrutiny over the long gap between SLS launches has intensified. Concerns have been raised that such a lengthy period between launches allowed skills and procedures to atrophy, leading to struggles in this second launch campaign. The new plan aims to rectify this situation by decreasing the time between SLS flights to as low as ten months. According to Mr. Isaacman, the new architecture would see the revamped Artemis III launching to LEO in 2027, with Artemis IV attempting the first crewed lunar landing in over half a century in early 2028, to be followed by Artemis V attempting the second in late 2028. 

However, to provide for this accelerated flight rate, Mr. Isaacman and Associate Administrator Amit Kshatryia have announced that significant changes will be made to the upper stage of the SLS vehicle. The upper stage currently stacked on SLS for Artemis II is known as the Interim Cryogenic Propulsion Stage, or ICPS. This single engine stage was derived from the heritage Delta Cryogenic Second Stage (DCSS), which saw service on ULA’s Delta III and Delta IV family rockets. However, as the name implies, ICPS was never intended as SLS’ permanent upper stage. Only three were produced, with the intent being to transition SLS to the larger, four engine Exploration Upper Stage, or EUS. This new configuration of SLS, with the EUS installed, is known as SLS Block 1B, and will provide a considerable performance boost over the current Block 1 configuration with the comparatively small ICPS. The EUS is mandated as a part of the SLS architecture in the NASA Authorization Act of 2010, and Congress reaffirmed the necessity of EUS in the NASA Reauthorization Act of 2022. 

In Friday’s announcement, Mr. Isaacman indicated that the SLS vehicle would be “standardized” to a “near-Block 1 configuration.” Maintaining the Block 1 configuration as it currently exists is not possible due to a lack of ICPS stages for missions beyond Artemis III. However, Mr. Isaacman’s statements Friday implied that instead of replacing ICPS with EUS as has been the plan, some new upper stage will instead be developed that is less performant than EUS, given his description of the configuration as being near to Block 1 rather than Block 1B. Statements from NASA confirmed that this is the case, at least for Artemis IV and V, days later. 

Ambiguities of this kind were a running theme throughout Friday’s news conference. During the questions period, Mr. Kshatriya was asked directly whether this change indicates a cancellation of EUS, a question which he declined to answer, indicating that neither he nor the Administrator were interested in commenting on “contractual issues.” Throughout the conference, both Mr. Isaacman and Mr. Kshatriya repeatedly dodged questions on specific architecture, with Mr. Kshatriya at one point saying “we’re not gonna do a whiteboard session on mission design here,” and Mr. Isaacman earlier responding to a question about HLS performance on Artemis III by noting only that the agency is “early in mission design.” 

Such ambiguity raises serious questions about the path forward for SLS and Artemis as a whole. EUS is at present legally required to be developed, as is the Gateway space station that the EUS will be instrumental in constructing. The unclear status of EUS has thrown the prospects for Gateway into serious doubt, along with it seemingly being written out of the mission plan for Artemis IV and V. Sources familiar with the matter have indicated to Space Scout that the Gateway team held an emergency all-hands meeting Friday, seemingly blindsided by the announcement. Gateway raises particular concerns, as international partners have already been brought aboard to develop hardware for the cislunar space station. 

Nearly a week later, the status of EUS and Gateway remain remarkably opaque. Social media reports reviewed by Space Scout indicate that stop work orders were sent to contractor employees working on EUS, but as of Wednesday morning there has been no official announcement of an intention to outright cancel the stage. In a draft of the 2026 NASA Authorization Act published 4 March by Ars Technica, the Senate appears to create a pathway to begin replacing EUS with a different upper stage, but that legislation does not require NASA to do so. It is also in very early phases of development, likely with months of work and multiple rounds of voting remaining before it will be ready for a signature by the President. Gateway’s situation remains even less clear, with only minimal nods to it in the draft Act, requiring the Administrator to merely brief “appropriate committees of Congress” on the plans for the project within sixty days of the Act’s enactment. 

This confusion and lack of transparency is not limited to the future of the Artemis program. NASA has also thus far notably not delivered photographs of the hydrogen line seal that caused issues in Artemis II’s first wet dress rehearsal, as they indicated they would in a previous press conference on 20 February. Broadly, these developments seemingly align with the Trump Administration’s campaign to expand executive authority by making broad, sweeping changes rapidly with minimal transparency or oversight, with the plan seemingly being to ask forgiveness from Congress after the fact rather than seeking permission from the outset. Counter to Mr. Isaacman’s promises of enhanced transparency within NASA during his tenure, he has thus far delivered enormous, sweeping changes to the agency he now helms with remarkably little oversight or clarity as to the nature of those changes, leaving both Congress and the American public they represent scrambling to keep up.