The Space Launch System (SLS) which will launch a crew of four on a trip around the Moon aboard their Orion Multi-Purpose Crew Vehicle (MPCV) during the Artemis 2 mission, has returned to the launch pad at Kennedy Space Centre’s Launch complex 39B (LC-39B).
The rocket had to be returned to the Vehicle Assembly Building on February 25th, 2026 after a helium pressurisation issue was found in the rocket’s upper Interim Cryogenic Propulsion Stage (ICPS), resulting in a helium leak. While the leak could be resolved with the vehicle on the pad, the need to ensure the ICPS has a stable helium pressure flow when in operation called for a rollback to the VAB to allow engineers unfettered access to the upper stage in order to resolve the problem.
The second roll-out to the pad mirrored the preparations for the Artemis 1 uncrewed mission in late 2022, which also saw the SLS rocket used on that flight rolled out to the pad, encounter issues (with the main propellant feed mechanism intended to fill the rocket’s tanks with liquid hydrogen and liquid oxygen) then rolled back to the VAB, before a second roll-out to the launch vehicle back to the pad. Given the overall success of Artemis 1 (despite leading to concerns over the Orion capsule’s heat shield), the roll-out, rollback, roll-back of Artemis 2 might be seen as a good (if delaying) omen.
The second roll-out took place overnight on March 20th, 2026 UTC (March 19th – 20th, US EDT) with the rocket and its Mobile Launch Platform (MLP) inching away from the confines of the VAB atop one of NASA’s mighty Crawler-Transporters. The 6.4 kilometre journey to the pad took almost 12 hours to complete, with the SLS and MLP positioned on the pad at around 15:20 UTC on March 20th.
The next launch window for the mission opens on April 1st, 2026 and runs through the first few days of April. NASA is currently targeting the very opening of the launch window on April 1st for a launch attempt, giving them maximum leeway should any minor issues occur or the weather decides to play a hand in matters.
Once launched, Artemis 2 will initially enter a 24-hour orbit around Earth. During this time several critical systems not carried aboard Artemis 1 will be tested and checked. Additionally the ICPS will be used to lift Orion into an elliptical orbit with a high apogee whilst imparting the craft with much of the velocity it will need to head for the Moon.
The ICPS will then separate from Orion and its European Service Module (ESM) and become a passive dummy target for the crew on Orion to carryout mock rendezvous and docking manoeuvres of the kind Orion will have to perform when operating around the Moon in future missions in order to dock with the lunar landing vehicles and (later) Gateway station.
Once these tests have been completed, Orion will use the ESM’s min motor to push it into a free return trajectory around the Moon on a trip lasting 9-10 days, affording the crew time to thoroughly check-out Orion’s systems and amenities.
EUS Replacement – I Called It
On February 27th, 2026, NASA provided an update on the entire Project Artemis, noting some significant changes to mission and vehicles (see Space Sunday: major Artemis updates and a rollback).
One of these changes was the cancellation of the planned Exploration Upper Stage (EUS) the more powerful upper stage for the SLS that has been under development at Boeing for several years, and would replace the ICPS on mission from around Artemis 5 (now Artemis 6).
At the time of the announcement no indication was given as to what would be used to replace the EUS and ICPS, or whether NASA was looking at something to match the ICPS or EUS in capabilities. However, in my article linked to above, I noted that as far as I could see, there were only two possible contenders: Blue Origin, with their New Glenn upper stage, or United Launch Alliance (ULA) with their Vulcan-Centaur V upper stage, part of a family of Centaur upper stages that has gained a long and venerable operational history.
On March 10th, 2026 NASA confirmed my thinking by making a procurement filing to replace the ICPS and EUS with ULA’s Vulcan-Centaur V. Whilst some modifications to the stage will be required, the V-C 5 was selected by NASA in part because of its pedigree stretching back over 60 years (which was seen as overcoming the fact the Centaur V has itself only flown twice), and in part because it is almost a simple drop-in replacement for EUS and (particularly) ICPS.
Once upgraded, the V-C 5 will offer more-or-less the same capabilities as ICPS, but not as great as the EUS. However, the lineage of Centaur means NASA has an assured route to have the system upgraded to meet future needs, if required.
The NASA announcement also indicated that, per my theorising, they had also considered the Blue Origin New Glenn upper stage. This was only ruled out on the basis it has only flown twice thus far – albeit completely successfully on both occasions – and NASA wanted an upper stage replacement will a decent launch / success / failure history and a track record of development they could properly evaluate.
ULA’s established infrastructure, resources, flight history, existing cross-program integration, and human-rating familiarity with the Centaur upper stage represents the only currently viable opportunity for the Government to accomplish Artemis mission objectives and requirements while also maintaining the agency’s programmatic goals.
– From the NASA procurement filing
So, yay me for calling it.
Artemis Accord Signatories Mull How to Deal with Emergencies and More
When a single nation goes to the Moon, there’s a pretty narrow field of operational requirements that need to be dealt with to keep people safe, avoid misunderstandings, demote working areas, and in handling thing like emergency situations.
When multiple nations decide to not only head for the Moon, but head for the same part of the Moon – in this case the South Polar Region – such requirements get a lot more complicated.
Currently, there are two confirmed groups of nations participating in projects aimed towards a long-term human presence within the Moon’s SPR – those of the US-led Artemis Accords (numbering, at the time of writing, 61 nations – not all of whom will be seeking to send their own astronauts to the Moon) and the China and (nominally) Russian-led International Lunar Research Station (ILRS), comprising (at the time of writing) 13 nations.
As such, serious considerations need to be given to managing diverse (or even competitive) lunar operations, denoting separate research and work environments, establishing buffer zone between different interests and working areas, and – critically – how to handle emergencies and provide emergency support.
The latter is something very much up in the air – although one would hope any emergency call for assistance would be responded to without regard to the nationality or allegiance of those making the call. For the former – the establishment of buffer zones is seen by members of the Artemis Accords as the way to go, although they prefer the term “safety zones”.
These would, in theory, allow signatory states pursue their own specific research interests on the Moon without the risk unintentional (or even intentional) interference from other member states. The problem is, how should a “safety zone” be defined? Should limits be placed on the size of such zones? How should they be recognised? How lawful would they be? How can they be enforced when it comes to non-Artemis nations?
A major concern here is that of territorialism: member states (or even the Artemis project as a whole) laying claim to a large area of the Moon, or even an entire region. Such claims are explicitly outlawed under the 1967 Space Treaty, but if sufficient resources of a valuable nature are found in a particular area of the Moon, is that treaty enough to stop a nation establishing a presence there and declaring an exclusionary “safe zone” around it before hoisting their flag and treating it as a national enclave? And what sort of response should that garner if it did happen?
We’re a long way away from where these issues might start to become problems, but they do need to be addressed in some form – and not just by members of the Artemis Accords – but by all nations, whether or not they are signatories to the Accords or the ILRS.
Lunar Ice Might be Rarer than Thought
One of the reasons for the interest in sending humans to the lunar South Polar Region has been the fact that the region is heavily cratered, and due to their position, many of the bottoms of these craters never see daylight or feel the Sun’s heat. Referred to as permanently shadowed regions (PSRs) it has been theorised that these craters could be home to large, accessible (or at least semi-accessible) deposits of the Moon’s water ice – which would be enormously beneficial to human operations on the Moon if they could be exploited.
This idea is backed-up by PSRs elsewhere in the solar system being home o water ice, including the planet mercury and the asteroid Ceres, to name two examples. However, despite all our orbital observations of the Moon, confirming the presence of water ice in lunar PSRs has been difficult; not least because of the orbital complexities involved in get a satellite to overfly them and the fact they are very deeply shadowed when seen form orbit.
To try to understand just how much ice might be present in the bottoms of permanently shadowed craters on the Moon, a team of US researchers operating out of the University of Hawaii at Manoa developed ShadowCam, an imaging system 200 times more light-sensitive than most other cameras used to study and map the Moon from orbit.
ShadowCam forms a part of the payload flown aboard the Korea Pathfinder Lunar Orbiter Danuri, South Korea’s first lunar mission, which entered orbit around the Moon in December 2022. Classified as a NASA experiment, ShadowCam first flexed its muscles in mid-2023, demonstrating it raw ability to see in to PSRs and reveal never-before-seen details.
More recently, ShadowCam has been engaged in a campaign to image multiple PSRs in the Moon’s Polar Regions (north and south) to reveal more of their secrets. And while the campaign has been very successful in providing new data and information on the observed craters, the one thing it hasn’t found is any sign of water ice deposits.
To be clear, any water ice contained within lunar craters is not going to be pure. It’s going to be mixed with and even covered by a layer of lunar regolith (the loose dust and rock fragments making up the surface material of the Moon). As such, these mixtures would produce different levels of reflectance and light scattering depending on the regolith-to-ice ratios encountered, although astronomers work on the basis that a mixture that is around 20-30% water ice would be enough to be detected by a sensitive-enough imaging system – and as noted, ShadowCam is very sensitive.
However, none of the dozens of PSRs on the Moon imaged by the instrument showed any signature that might indicate water ice was present in some degree. This doesn’t necessarily mean the water ice is not there; it could exist in percentages as low as 10%, or even in single digits – as these are levels too small for ShadowCam to currently detect, although the University of Hawaii team hope to be able to use software updates in their processing software that would reveal water ice in concentrations as low as 1%.
But that said, the real rub here is that even if such low percentages of water ice are revealed, and assuming ShadowCam’s results hold as more lunar PSRs are examined, then it is obvious that the hoped-for abundance of water ice to assist in lunar operations simply don’t exist or might be so small as to not be worth the expense and effort in trying to exploit them. As such, the water needed to help sustain human operations on the Moon and to enable various construction and technology options is going to become a further payload mass that will have to be routinely shipped from Earth.
Inara Pey: Living in a Modemworld 