Author: Inara Pey

Yes, there’s been a lot in this column about Project Artemis and the US-led programme to return humans to the Moon, and while it might make Space Sunday sound a bit like a scratched record (Artemis..,Artemis…Artemis…), there is good reason for this: there’s a lot of news about the entire programme, from the anticipated launch of Artemis 2 and its crew on a trip around the Moon and back, to the focus of the main part of this article: major changes to the Artemis programme as a whole; so bear with me!

NASA’s current Administrator, Jared Isaacman, continues to surprise and impress despite concerns over his non-NASA activities and involvement with favoured space contractors. In my previous Space Sunday article, I covered Isaacman’s direct and open approach to the problems endemic to the Boeing CST-100 Starliner programme, and to the core of NASA’s management responsible for managing it (with two of the most senior resigning in the aftermath).

Following the press conference on that matter – which included the reading out of a letter to all NASA staff-  Isaacman was present at a February 27th, 2026 Project Artemis update which carried its own surprises whilst signalling a change in direction for the programme – potentially putting it on a far better footing that had previously been the case.

The update saw a number of significant announcements:

• The much-criticised Space Launch System (SLS) is not to be cancelled as yet – something many outside NASA have called for, despite there being no currently-available launch vehicle that can match its capabilities (see: Space Sunday: of Artemis and Administrators).
• However, SLS will be changing, with one significant element – the Exploration Upper Stage – now cancelled.
• As a result of the Exploration Upper Stage cancellation, the Block 1B variant of SLS will no longer be part of the SLS enhancement programme, nor, potentially, will be the even more powerful Block 2 version.
• NASA will attempt to raise the launch cadence for SLS from approximately once every 3 years to once every 10 months.
• Artemis 3 is no longer a lunar landing mission, but will be an Earth-orbiting test flight involving at least Human Landing System vehicle.
• The original Artemis 3 lunar landing mission is therefore redesignated Artemis 4, but the time frame remains a (optimistic) 2028.

SLS Changes

Much of the critique surrounding SLS has been on the matter of launch cost, which stands at some US $2.5 billion per vehicle. However, these costs are based on the overall development of SLS and Orion, and are not simply the physical cost of get a specific launch stack off the pad. This is something many of the louder voices raised against SLS – notably those from the SpaceX corner – tend to ignore when pointing to the “lower” cost of something like Starship, which is put at around US $100 million per launch. In this, it needs to be pointed out that this has yet to be proven, as Starship has yet to actually achieve orbit, and even then, launch costs for NASA could be as much as US 1.3 billion, when all of the required tanker launches and the launch of the (also unproven) orbital propellant station the Starship HLS will require just to get itself to the Moon.

That said, SLS is a costly launch mechanism; in 2023, the US Government Accountability Office (GAO) issued a report stating SLS was “unsustainable” at current spending levels, and suggested that launch costs could increase over time to as much as US $4 billion as a result of the technical complexity of the system, plans to try to extend its capabilities and its low launch cadence.

Exploration Upper Stage and “Near Block 1” SLS Development

Dropping the Exploration Upper Stage (EUS) from the SLS development curve should address some of these concerns over rising costs.

EUS was due to debut with the Block 1B development of SLS, providing it with a more powerful and capable upper stage than the current Interim Cryogenic Propulsion (ICPS) upper stage. As it is now cancelled, NASA is pivoting away from the Block 1B version of SLS in order to develop a “near Block 1” upgrade, which will use a new upper stage in place of both ICPS and EUS.

Just how much this will save is open to debate: some US $3 billion has already be spent in developing EUS, and there will obviously be costs involved in developing a commercially-based replacement for it and ICPS. But there are other another compelling reasons for replacing EUS with a unit more in line (if more powerful) than the ICPS: simplicity of overall design and design and continuity of experience.

The Block 1 SLS is now a known creature, foibles and issues all taken as read. It’s a vehicle NASA is continually gaining knowledge and understanding in operating. Block 1B, with the EUS, it’s extended core stage elements (extended interstage and the enlarged universal stage adaptor) is a different beats, liable to demonstrate different flight characteristics and dynamics as well as introducing new elements which could have their own teething problems. Sticking with an only slightly modified vehicle to supersede the current Block 1 vehicle, reduces many of these factors, allowing NASA to “standardise” the SLS design and continue to gain data, knowledge and understanding on  / of its characteristics incrementally. This was pretty much how things were handled back in the Apollo era, and the approach has a lot going for it, a point acknowledged during the briefing.

After successful completion of the Artemis I flight test, the upcoming Artemis II flight test, and the new, more robust test approach to Artemis III, it is needlessly complicated to alter the configuration of the SLS and Orion stack to undertake subsequent Artemis missions. There is too much learning left on the table and too much development and production risk in front of us. Instead, we want to keep testing like we fly and have flown. We are looking back to the wisdom of the folks that designed Apollo. The entire sequence of Artemis flights needs to represent a step-by-step build-up of capability,

– NASA Associate Administrator Amit Kshatriya

Exactly who will provide the replacement for ICPS / EUS and what form it will take was now discussed at the briefing. However, it was made clear that all of NASA’s contractors and partners in Artemis were consulted through the driver to redirect the programme, and all have been supportive of the moves – even Boeing, who stand to lose the most with the EUS cancellation, whilst SpaceX and Blue Moon have both opted to “accelerate” the development of their HLS systems.

Perhaps two of the strongest potential contenders for producing a new upper stage for SLS are United Launch Alliance (ULA) and Blue Origin.

ULA already has the powerful cryogenic Centaur V upper stage. Centaur is a venerable launch vehicle stage with a lot of expertise behind it, with the Centaur 5 already forming the upper stage of ULA’s Vulcan-Centaur rocket. Blue Origin, meanwhile, has the upper stage of their New Glenn booster. Whilst a “new kid on the block”, the stage has already proven itself reliable on two high-profile flights for New Glenn, and will shortly be back in action for a third flight, thus experience is quickly being gained in its operation. Further, blue Origin are already looking to develop an enhanced version of the stage in line with their plans for an even more powerful variant of their New Glenn vehicle, thus there is potential here as well.

Neither Centaur V nor the New Glenn upper stage would be suitable for SLS straight off the shelf, but using them as either a basis for a new stage design or developing a variant off of an existing design (Blue Origin) could significantly reduce the costs and time involved in developing and testing a new SLS stage.

Launch Cadence

Another mitigating factor when it comes to reducing overall costs is the decision to try to launch SLS on a greater cadence than has thus far been seen. Isaacman would specifically like to see an SLS / Artemis launch once every 10 months, putting Artemis almost on a similar launch cadence as Apollo. Doing so will likely increase Artemis costs, but it also brings some very clear benefits:

• Personnel expertise. Gaps measured in years between launches can result in personnel expertise loss as people become tired of waiting for the next launch and seek a career move elsewhere, taking their expertise with them. A faster launch cadence with clear mission objectives is more likely to keep more of that expertise in-house at NASA for longer.
• It makes Artemis potentially more robust, presenting NASA with a chance to present a clear roadmap for achieving the goals of establishing a lunar base and maintaining a human presence there. Clear time frames and mission objectives also help Congress in allowing the money to flow into NASA to support the programme.

Of course, achieving such a cadence is no easy task; thus far, Artemis 1 and Artemis 2 (of which more below) have demonstrated that, like it or not, SLS and its ground support systems are extremely complex and subject to technical issues which can so easily upset launches.

Artemis 3 – No Longer Aiming for the Moon

The decision to “divert” Artemis 3 to an Earth orbital mission was perhaps the biggest surprise in the update – although “divert” is not entirely correct.

What is proposed is the insertion of an additional Artemis / SLS launch between what is currently Artemis 2 and what would have been Artemis 3, the first crewed lunar landing in the programme. That mission – presumably utilising the same crew – will now effectively become Artemis 4, with the new Earth-orbital mission taking the name Artemis 3.

The aims of the revised Artemis 3 mission – scheduled for a 2027 launch – so far comprise (additional mission goals may be added as the mission requirements are further assessed):

• On-orbit rendezvous and docking with one or other (or possibly both) of the current Human Landing System vehicles in development: Blue Origin’s Blue Moon Mark 2, and the nascent SpaceX  Starship-derived HLS.
• Perform integrated checkout of life support, communications, and propulsion systems on both HLS vehicles and assess their suitability / practically for zero gravity operations.
• Carry out comprehensive tests of the new extended extravehicular activity (xEVA) suits to be used both with Artemis as as a replacement for the current generation of US EVA suits on the International Space Station.

This is actually a smart step on NASA’s part, and harkens back to the Apollo era and specifically, the Apollo 9 mission.

Under the original Artemis plan, no provision was made for any on-orbit human testing of the SpaceX HLS vehicle ahead of Artemis 3. Instead, SpaceX were obliged to send and uncrewed HLS lander to the Moon and conducted an automated landing (or possibly 2) – but there were no provisions for any crewed testing of the vehicle prior to Artemis 3.

Conversely, Blue Moon Mark 2, with its longer lead time (not being required – in theory – until Artemis 5 under the previous plans, and now Artemis 6 under the revised approach) would have undergone Earth orbit crewed testing prior to being used for lunar operations.

As such, this new step offers a means by which both vehicles (assuming both are ready for a 2027 launch) can be properly tested in Earth orbit, where the risks to the crew are potentially reduced, simply because they can use Orion to make a fast return to Earth. Thus, both can be properly assessed, including any shortfalls they might exhibit in advance of any attempt at a lunar landing. This is something that is clearly much better for all concerned than otherwise sitting and crossing fingers, as would have been the case with the original Artemis 3 mission.

Other Changes

Additionally, the Artemis Update indicates further changes within NASA’s operating structure as a whole with a drive to rebuild core competences and to better oversee commercial contracts and be more hand-on with commercial partners (as indicated in the Starliner press briefing). Key to this will be the implementation of standard processes right  across the space agency, not just covering Artemis, but all commercial partnership and space projects.

Further, the space agency will embark on a process of new and more extensive involvement with Congress to keep them appraised of progress with SLS and Artemis, and has already embarked on a restructured process of negotiating with commercial partners and engaging them in NASA’s decision-making processes.

In the meantime, the NASA announcement has received a largely positive reaction from observers and stakeholders, and the approach it advocates potentially helps put Project Artemis on a much more realistic footing to achieve its goals.

Artemis 2 SLS Rolled Back to the VAB

As I reported in my previous Space Sunday update, Artemis 2 suffered another setback in plans to get a crewed Orion space vehicle on a 10-11 day free return flight to the Moon (with a day spent in a high Earth orbit beforehand) off the ground in March.

The issue this time resides within the helium pressurisation system within the rocket’s Interim cryogenic Propulsion Stage (ICPS), which is required to get Orion to orbit and plays a role in meeting all of the mission’s planned goals. As I noted at the time of writing that update, NASA felt there were two potential routs to resolving the issue: by leaving SLS on the pad at Kennedy Space Centre’s Launch Complex 39B (LC-39B). Or rolling the entire stack back to the Vehicle Assembly Building (VAB), where a more comprehensive examination of the issue could be performed.

It was decided the latter was the better choice of action, and so on February 25th, 2026, the Artemis 2 launch vehicle and its Mobile Launch Platform were slowly and gently rolled back to the VAB atop one of the famous Crawler-Transporters.

The physical move of the rocket and its launch tower structure commenced at 14:38 UTC, and took over 11 hours to complete, the Crawler-Transporter inches the entire structure into one of the VAB’s massive high bays inch by inch with incredible precision given the overall size of the Crawler-Transporter and its payload. The night-time arrival also afforded some unique views of the entire stack edging up to and then entering the VAB.

Currently, the hope is to correct the helium pressure issue in time to get the rocket back to the pad so it can meet an April 1st through 6th (inclusive) launch window. However, more extensive rectifications to the helium system, if required, will be left for the next SLS vehicle which will carry the crew selected for the new Artemis 3 mission to orbit.