Spaceflight – Inara Pey: Living in a Modemworld

Space Sunday: looking at the Artemis HLS vehicles

Posted on May 10, 2026 by Inara Pey

The Artemis Human landing Systems (aka lunar landers) are being developed by private companies, with Blue Origin developing the Blue Moon Mark 2 HLS (l) and SpaceX the Starship HLS. Credits: (2024) Blue Origin and SpaceX

As is well-known, the US hopes to make a return to the surface of the Moon with astronauts in 2028. This has been, and remains, a questionable time frame for a number of reasons. As I recently reported, NASA’s own Office of Inspector General (OIG) issued a report indicating the new xEVA suits Axiom Space is developing for use on the International Space Station (ISS) and in lunar missions might not be ready for lunar operations until 2031.

Another bump in the road for 2028 is the availability of a vehicle to actually get crews from lunar orbit down to the surface of the Moon and back to orbit again. Again as I’ve oft mentioned, two companies are in the running to supply this vehicle – called the Human Landing System (HLS) in NASA parlance: SpaceX and Blue Origin. The two systems are very different to one another, and each has built-in complexities, some of which are down to NASA’s decision making, others are due to the choices being made by the two companies.

The biggest NASA-defined challenge is that both HLS vehicle must utilise cryogenic propulsion using either liquid oxygen and liquid hydrogen (Blue Origin) or liquid oxygen and liquid methane (SpaceX). The problem here is twofold: mass, and the fact that cryogenic propellants, as the name indicates, require very low temperatures and relatively large volumes in order function, otherwise they will simply (and dangerously) “boil-off”.

The mass of the propellants means that neither HLS system can be launched with the propellant load needed to reach the Moon, enter orbit and then deliver a crew to the surface of the Moon and back to orbit. They have to launched sans propellants and “refuelled” in space. This is turn brings up two issues.

The first is that no-one has ever performed the large-scale (100+ tonnes) transfer of cryogenic propellants in zero gravity (“refuelling” of the International Space Station is commonplace, but uses hypergolic propellants, which are completely different in nature and handling). Thus, both companies must develop and test mechanisms for the transfer of propellants from one vehicle (the “refuelling tanker(s)”) to another, and test then well before 2028 and Artemis 4.

A 2022 concept rendering of two SpaceX Starship vehicles mated back-to-back for cryogenic propellant transfers. Other options under consideration are an engines-to-engines docking for propellant transfer or placing a “fuel depot” in orbit and having the “tanker” missions fill it, before the Starship HLS visits it to take propellants it needs. Credit: SpaceX

The problem of boil-off is potentially more significant. As noted, cryogenics require extremely low temperatures if they are to remain liquid. Should they rise above the required temperatures they will sublimate to gas (boil off), drastically increasing their volume. Thus, if some of this gaseous propellant is not vented from the tanks, it could end up rupturing them completely, destroying the vehicle. Hence why rockets using cryogenics are seen venting clouds of propellants between fuelling and launch.

In space, any vehicle using cryogenics will spend the majority of its time in temperatures of around 121ºC. Even with tank insulation, this means there is likely to be significant boil off, meaning one of three things (or a possible combination of two of them):

The Super Heavy booster used in Starship’s 4th integrated flight test (2024) venting boiled-off liquid oxygen from its upper tank and liquid methane from the lower during a propellant load test. Credit: SpaceX

The excess gases must be vented to space (and the inevitable thrust they cause countered), which in turn will require further propellants to offset such loss prior to the vehicle leaving orbit.
Or, the vehicle must include some means of capturing the gas, and refrigerating back down and cycling it back to the tanks – all of which increases vehicle complexity and mass.
Or the vehicle must be equipped with some passive means of keeping the propellants as close as possible to their desired liquid temperatures, minimising boil-off, again potentially increasing vehicle mass and complexity.

Thus, both SpaceX and Blue Origin must both find a way of minimising this propellant loss. In the case of SpaceX, this appears to be primarily in the form of loading as much in the way of propellants as possible into the vehicle so that the overall venting does not impact the vehicle’s capabilities; hence the estimates that 8-16 Starship “refuelling” launches might be required for the SpaceX HLS to carry out its mission.

Rather than relying on a massive HLS vehicle with huge propellant tanks, Blue Origin have opted for a much smaller, lighter vehicle (45 tonnes when loaded with propellants compared to the approx. 238 tonnes of the SpaceX HLS when loaded with propellants). However, it needs to be supported by an additional vehicle: Cislunar Transporter.

The latter is a combination of propellant tanks (which will incorporate some form of “zero boil-off” capability Blue Origin has apparently developed) and space-going tug. Following launch, it is designed to be refuelled by a number of New Glenn launches with around 100 tonnes of propellant. It will then dock with the Blue Origin HLS, once launched, and deliver it to lunar orbit, transferring some of its propellants to the lander’s own tanks so it can carry lout its mission.

In addition, and unlike the SpaceX HLS, the Cislunar Transporter will be capable of returning to Earth, where it can be loaded with further propellants and thus service additional flights of the Blue Origin HLS to / from the lunar surface.

*A rendering of the Blue Origin Cislunar Transporter in Earth orbit and with its solar arrays for electrical power unfurled. Credit: Blue Origin (2025)*

But even with smaller, lower-mass vehicles, Blue Origin faces pretty much the same challenges as SpaceX in terms of propellant loading the storage. So, leaving these issues aside, how is the general development of both systems going and which is likely to get the prestige of returning astronauts to the surface of the Moon first?

On paper, both companies appear to be pretty neck-and-neck in terms of vehicle development. SpaceX for example, has completed around 50 target milestones with its Starship-derived HLS. These include land testing of an airlock test article; the development (with NASA) of an elevator system to be deployed when the vehicle is on the Moon in order to get crews two and from their facilities on the vehicle (roughly 45 metres above the lunar surface) and “ground level”; a “full test” of the life support systems; testing the Raptor engine’s ability to re-light in a wide range of temperature environments; development and testing of the SpaceX-Orion docking system and the vehicle’s avionics, flight and navigation software; mock-ups and testing of pre-launch ground support infrastructure, etc.

Blue Origin has also completed a similar number of tests on both software and hardware, including vacuum testing of the BE-7 engine to be used by their HLS, their cargo lander and the Cislunar Transporter. However, their testing is potentially ahead of SpaceX in some areas, and liable to quickly move ahead in others.

*A mock-up of the airlock system to be used on Blue Origin’s HLS vehicle being evaluated by astronauts in the Neutral Buoyancy Laboratory, Johnson Space Centre, 2025. Credit: Blue Origin*

For example, where SpaceX has been testing its airlock design on land, Blue Origin has completed testing their airlock system within NASA’s Neutral Buoyancy Laboratory at the Johnson Space Centre. This has allowed space suited astronauts to test the airlock in similar circumstances to those they will experience on the Moon.

As well as this, the company has an integrated, full-scale mock-up of their HLS vehicle. This has allowed Blue Origin and NASA to collaborate directly on the design of the vehicle, including accessibility to critical systems, placement and operation of manual flight control systems, data displays, life-support systems, and the layout of essential crew facilities (toilet, food preparation air, food and beverage storage, personal spaces, etc.), in readiness for the manufacture of the initial HLS craft.

Further, later this year Blue Origin is due to launch the first of its Blue Moon Mark 1 cargo landers to the Moon. Whilst much smaller than the Blue Moon Mark 2 HLS, and only capable of delivering up to 3 tonnes to the Moon’s surface (no “refuelling” required), Blue Moon Mark 1 uses the same automated flight control, space navigation, landing guidance, data communications and propulsion management software as will be used on the Blue Moon Mark 2 HLS. Thus this first Mark 1 mission, featuring the lander Endurance, will be both a practical mission delivering two NASA experiments to the lunar surface and serve as a “pathfinder” test of these automated systems and the capabilities of the BE-7 engine.

If successful, Endurance will be followed in early-to-mid 2027 by a second cargo mission to deliver NASA’s cancelled-then-resurrected VIPER lunar rover mission to the Moon. Assuming either or both of these missions perform as expected throughout, they will pretty much indicate the flight software and BE-7 are fit-for-use within the Blue Moon HLS.

Currently, Endurance is at Blue Origin’s facilities at Kennedy Space Centre, Florida, where it will be integrated with its launch vehicle. Prior to arriving at KSC, Endurance had undergone extensive thermal vacuum chamber testing at NASA’s Johnson Space Centre, exposed the thermal and pressure environments it will face during its mission, and testing its overall readiness to fly.

The commonality of systems is also seen with the Cislunar Transporter. This was originally going to be developed by Lockheed Martin, but is now an in-house project at Blue Origin. This means that as well as utilising the same BE-7 engine, the overall design of the Transporter borrows heavily from the New Glenn upper stage, greatly reducing its development cycle and allowing it to use the Tanks and engine mounts, etc., from the New Glenn upper stage, greatly simplifying its design whilst enabling it to be manufactured on the same production line.

Like Endurance, an initial Cislunar Transporter prototype spent mid-2024 undergoing extensive vacuum and thermal testing at a facility at Edwards Air Force Base, California. As a result, production of the Transporter is due to start at Blue Origin’s primary plant at Kennedy Space Centre.

*The SpaceX HLS airlock test article developed for ground-based testing of the system. Credit: SpaceX*

It is this progress within Blue Origin, countered by a perceived lack of significant progress by SpaceX on their HLS through 2025, which led NASA’s former Administrator, Sean Duffy to announce the first Artemis crewed landing on the Moon would not be an SpaceX exclusive, but would feature whichever HLS system was fit-for-purpose and ready for a 2028 launch; a decision since confirmed by the current Administrator, Jared Isaacman.

Under Isaacman’s leadership, there is to be a crewed Earth-orbital test of the HLS vehicles in 2027 under the Artemis 3 banner. This test could be with both HLS vehicles, if both are ready in time, or by whichever is available, and will be used in a final determination as to which vehicle Artemis 4 will use.

However, whether Blue Origin or SpaceX will be in position to meet a 2027 HLS test flight is entirely open to debate. Both companies have already asked NASA to push back the test flight from mid-2027 to late 2027, which the agency has done, but Blue Origin remains somewhat tight-lipped about the overall development status of Blue Moon Mk2 and Cislunar Transporter.

Meanwhile, in promising to accelerate its HLS development, SpaceX has set itself some hefty goals for 2026, especially considering we’re fast closing in on being half-way through the year. These include:

Actually getting a Starship to orbit.
Demonstrating Starship can reach orbit with a “useful payload” – thus far, the “version 1” and “version 2” variants have either sacrificed payload lift capability in favour of just getting to sub-orbital velocity, or sacrificed the ability to achieve orbit in favour of carrying a modest payload – Starlink demonstrators – to sub-orbital velocity. Thus, hopes are now pinned on “version 3”, due to make it s first launch attempt sometime in the next month.
Carry out an on-orbit cryogenic refuelling mission.
Undertake a “long duration” Starship flight. This was initially defined by the SpaceX CEO as a mission to Mars, now all but abandoned for 2026 (and likely the foreseeable future), leaving the context of the flight uncertain.

There is also the matter of actually recovering Starship vehicles as they return to Earth. This is an essential part of the equation for SpaceX, as the company has indicated it will pay for all of the HLS “refuelling” launches, estimated at up to US $400 million a throw if an entirely new vehicle is used for each if these launches.

Given all that has to be achieved in just 18 months, it may yet ben that the Artemis 3 mission might be further pushed back. If so, then Artemis 4 will likely not occur until 2029 at the earliest (assuming the Axiom xEVA space suits are ready by then). If this happens, then the door to which HLS system is used would again be thrown wide open.

However, there are two additional factors outside of development time frames and general vehicle readiness which could play into Blue Origin’s hands, at least as far as the Artemis 4 mission is concerned: a) vehicle size and mass distribution, b) risk mitigation.

The SpaceX Starship HLS is 52 metres tall and 10 metres in diameter, with a relatively narrow landing leg spread compared to its height. When it comes to landing on the Moon, with the majority of its propellant spent, it also has a very high centre of gravity due to the engines and propulsion systems, crew facilities, power and life support systems, etc., all located in the upper third of the vehicle. Blue Moon Mk2 is only 15.3 metres tall and its centre of mass is in is lower third. It also follows the Apollo lunar lander approach of having a broad spread with its landing legs for increased stability and support.

The Blue Moon HLS lander (l) compared to the Apollo lunar lander (l). Note how the Blue Moon vehicle has a low centre of mass – all major systems and crew facilities at the base, the largely-empty propellant tanks, together with the solar arrays (shown folded) at the top – and a broad set of landing legs similar to Apollo’s to better support it. Credit: Blue Origin

Whilst it is essential all Artemis missions to the Moon minimise the risks faced by their crews, given the “first time” nature of Artemis 4, the use of Blue Origin Mk2 might be seen as the better choice of lander, simply because its squat, low centre of mass design minimises the risk of it toppling over when landing on a unknown surface. The same cannot be said with certainty for the SpaceX design, where even a minor depression directly under one of its landing legs could result in disaster. As such, use of this vehicle might be better suited until after “eyes on the ground” have been able to more accurately determine relatively “safe” areas where it might land.

So, which vehicle do I think will get to fly with Artemis 4? Allowing for the aforementioned caveat of missions being pushed back and assuming SpaceX don’t find a way of testing an uncrewed version of their vehicle to better assess the risk of toppling-on-landing, I do tend to lean towards Blue Origin. While they face challenges – some of them the same as SpaceX, as noted – their approach just comes across as cleaner, more fit-for-purpose. But then, I don’t work for NASA.

Space Sunday: Radiation and propulsion, interstellar asteroids and, yes, Artemis

Posted on May 4, 2026 by Inara Pey

Lockheed Martin is one of several organisations which has drawn up plans and renderings for a possible humans to Mars mission. The Mars Base Camp interplanetary craft utilises the Orion spacecraft as the command and control facility, with a cryogenic propulsion system somewhat similar to the (now cancelled) ULA Interim Cryogenic Propulsion stage (ICPS) used with current SLS rockets, together with both habitat and laboratory modules for crew space, and two additional Orion vehicles for use as orbital excursion craft whilst in Mars orbit. Such spacecraft and mission face a wealth of issues before they can become a reality. from crew mental health through to technical issues such as radiation shielding and propulsion systems. Credit: Lockheed Martin.

I’ve written on numerous occasions about the various challenges facing any human mission to Mars. Perhaps chief among these challenges are the matters of radiation exposure and transit time. As I’ve noted in past articles (such as this one) on this topic, crews going to Mars face multiple risks, just two of which are radiation (both solar radiation and Galactic Cosmic Rays (GCRs)) and transit times.

The former is particularly deadly in that solar storms can deliver lethal doses of radiation exposure over a matter of a few hours (or less). However, they can be mitigated through the use of careful mission planning (avoiding, where possible, launch windows when solar activity is at or near its peak); and providing on-board radiation shelters which use a dozen centimetres or so of a suitable material (such as water) which can be used should a storm threaten.

By contrast, GCRs are less “immediate” in the risk they present, but they are constant and all-pervasive. They are also far more high energy than solar radiation, making shielding against them a more complex issue. requiring a lot more in the way of shielding. For example, gamma radiation from a typical solar storm requires around 13-15cm of water to mitigate much of its threat; GCRs require at least two metres of water (at one tonne per cubic centimetre) to reduce the threat by 50%. And while they might not be immediately deadly, GCRs can cumulatively have a major impact on health, such as reactivating cancer-giving strains of the herpes virus normally dormant in the human body, such as the highly contagious Epstein–Barr virus (EBV).

Ergo, crewed Mars vehicle require more wide-ranging and effective shielding in order to reduce the long-term impact of GCRs on Mars-bound (or Earth-returning) crews. Currently, two such shielding materials exist: Kevlar and high-density polyethylene (HDPE). Both are very effective in absorbing GCRs – just 5 cm of either will do the same job as 2 metres of water. However, while both could be incorporated into the structure of a crewed Mars vehicle, they would need to offer protection right across all crewed areas, not just a relatively complex shelter. As both have a mass in the same orbit as water (1 gram per cubic centimetre for the latter; 980 grams per cubic centimetre for HDPE and up to 1.44 grams for Kevlar), this means that both could come with a significant mass penalty.

As such, more lightweight – and preferably more efficient – shielding materials are required. One of the most promising is that of carbon nanotubes, some of which are very efficient in dealing with various forms of radiation. Single-walled carbon nanotubes (SWCNTs) can reflect up to 99.9% of solar electromagnetic radiation striking them, whilst boron nitride nanotubes (BNNTs) can absorb some 72% of neutrons (common to GCRs) in just a thin layer – more than can be achieved by using 5 cm of HDPE or Kevlar. In fact, NASA’s Langley research centre has in the past experimented with trying to “weave” BNNTs into structure that could be used within habitat units of spacecraft.

*NASA Langley is working on using “GCR-proof” BNNTs within structures such as habitat units, space vehicle elements – and even as a flexible lining in space suits. Credit: NASA*

The problem here is that nanotubes are both expensive to manufacture and difficult to manipulate / use. Hence why, in the 35 years since serious nanotube production started, less than 10,000 tonnes have been produced world-wide. However, a team of researchers at the Korea Institute of Science and Technology (KIST), have been looking at the potential for nanotubes in a range of applications – including their use as a shielding material – and have developed a means of potentially overcoming the issue of using nanotubes to create materials the application of 3D printing.

In particular they have developed a means to combine both SWCNTs and BNNTs into “mats” of material which can be “woven” together as a part of the printing process to fulfil a number of roles. Most particularly, in terms of space applications, these “mats” remain all of the radiation shielding capabilities common to both SWCTs and BNNTs. Thus, single layers of a “mat” could be used to provide individual protection for circuitry and chips forming the electronics on robot spacecraft, or be layered to produce very lightweight, efficient and very flexible material for shielding all the habitable areas of a crewed spaceship. What’s more, the material can withstand massive temperature swings (from -196ºC to +250ºC), potentially allowing it to be used both internally and externally on space vehicles.

This material represents a completely new concept in shielding technology-it is as thin as tape and as flexible as rubber yet simultaneously blocks both electromagnetic waves and neutron radiation.

– Dr. Joo Youngho, principal investigator, Ultrathin, Stretchable, and 3D-Printable Complementary Nanotubes–Polymer Composites for Multimodal Radiation Shielding in Extreme Environments

The research still requires a lot more work before this approach can be thought of as truly viable, but the implications of such a shielding capability for something like crewed missions to Mars would be enormous.

Potential uses of the new 3D printed nanotube “mat” developed by the Korea Institute of Science and Technology (KIST) including full spacecraft radiation shielding (A), to individual protection for electronic components (B) to creating more rigid forms (G, H, J) and the ability of the fibre to shield against radiation (D, E). Credit: KIST

Currently, it takes between 6 and 9 months to travel between Earth and Mars (or vice versa) when launching at the most energy-efficient times (approximately once every 26 months). This could put significant strain on a crew, limited as they would be to just a small circle of people with whom they could communicate in real-time and the limited amount of space available within their spacecraft in which they might fine solitude and peace keeping their own company.

However, if we had a more efficient propulsion system, one that could use a lot less fuel far more efficiently and for longer, then it would be possible to break out of the current 26-month, 6-9 month transit flight constraints to a greater or lesser degree. This would help reduce the stresses that might otherwise build-up in such a restricted environment, and also help reduce (to a degree) the crew’s deep-space radiation exposure risks.

One way to achieve this would be through the use of Nuclear Thermal Propulsion (NTP). However, such a system has yet to be developed and brings with it the need for shielding for the crew against the nuclear reaction, with all the added mass and complexity that brings.

Another alternative is that of electric propulsion. This is not as powerful as NTP and cannot even match the specific impulse that can be generated by chemical motors. However, it is a) highly efficient, b) already in use and c) unlike chemical rockets, it can maintain its thrust more-or-less continuously for comparatively little fuel mass. Take NASA’s mission to the asteroid 16 Pysche, for example. This uses Hall-effect thrusters which, while relatively low-power have maintained a steady thrust since the mission launched 2.5 years ago, accelerating the spacecraft from a few tens of thousand km/h as it departed Earth orbit to more than 135,000 km/h today – and it is still accelerating for the time being; all for just 1.6 tonnes of propellant.

*A small-scale Hall-effect thrust producing thrust (left) and shut down (r). Credit: unknown*

However, the Psyche spacecraft masses just 2,6 tonnes overall. A crewed Mars vehicle, with its habitat units, control centre, solar arrays for electrical power, life support systems and so on, is going to mass tens of tonnes (a minimum of 45 tonnes has been estimated for just a basic habitat/lander craft). As such, if electric propulsion is to be used, then much more powerful thruster systems will be required.

This is exactly what NASA’s Jet Propulsion Laboratory (JPL) has been working on: a “next generation” nuclear-electric motor called the magnetoplasmadynamic (MPD) thruster. Rather then just relying on electric power to drive the thruster, the MPD introduces a magnetic field into the drive process, making the thruster far more efficient and with a greater output. It also utilises lithium as a the propellant rather than the more usual xenon or krypton, for an increased energy output. As a result, a test article of the MPD has already proven itself to be able to operate for relatively long periods (albeit days rather than months or years), producing a steady 120 kilowatts of thrust, more than 25 times that produced by the hall-effect thrusters on the 16 psyche mission.

This is an impressive start, but to power a crewed spaceship of the kind currently being considered for human Mars missions, the propulsion system would have to be capable of consistently generating up to four megawatts of energy, both to accelerate the vehicle during the first half of its voyage out from Earth (or Mars) and then as a braking system to reduce its velocity to a point where it can enter orbit around its destination. However, the JPL team are reasonably confident that with time and experimentation, they could likely iterate the MPD to a point were it is consistently generating around a megawatt of power, thus allowing multiple engines (4-6, allowing for reserve engines being carried to deal with any failures) to be used to propel a potential Earth-Mars-Earth vehicle, all of which would require far less fuel than any chemical propulsion system, and would not require refuelling at Mars.

There are a few wrinkles in this approach that need to be addressed, however. For example, to produce such a level of power output, the MHD would also produce a lot of heat – around a constant 2,800ºC. Thus, the materials used in the thruster system would have to be capable of running continuously in the face of this temperature for thousands of hours of use. As such, much more in the way of development and testing is required before the MPD thruster would be ready for practical use – which will take years or possibly decades. But once developed and tested, it could offer a means to either shorten the transit times between Earth and Mars by virtue of its constant thrust, or deliver heavier payload to Mars over roughly similar time-frames as the current Hohmann orbits, and with none of the angst people have around nuclear thermal systems.

3I/Atlas

On July 1st, 2025, 3I/ATLAS was confirmed as the third known interstellar object (ISO) to be passing through the solar system. It also became the third such object to ignite daft claims that such objects are of alien manufacture sent to spy on us, despite the evidence it is lactually a comet. By the end of October 2025, it was passing around the Sun at the start of its way out of the solar system, and by April 2026 it was once again passing beyond the orbit of Jupiter.

However, between July 2025 and April 2025, 3I/Atlas was the subject of intense study by observatories on the ground and in space, with some interesting discoveries being made along the way. The James Webb Space Telescope (JWST), for example, revealed the comet’s coma (the cloud of dust and material formed when a comet approaches the Sun and its ices sublimate, releasing material) to be composed primarily of carbon dioxide in an 8:1 ratio compared to water, much higher that with solar comets, which typically have a 4:1 ratio; indicating the comet likely formed in a very different environment compared to our own solar system.

This view was further enhanced following observations of the comet made by the Atacama Large Millimetre/sub-millimetre Array (ALMA) located high in the Chilean Andes. These revealed 3I/ATLAS is made of an astonishingly high ratio of semi-heavy water (HDO, also known as deuterated water, on account of one of the hydrogen atoms being replaced by a deuterium atom) relative to water.

On Earth, approximately 1 in 3,200 water molecules are HDO (with one in 41 million being heavy water (D2O), with which semi-heavy water should not be confused). On 3I/Atlas, the abundance of HDO is around 40 times higher than the abundance of semi-heavy water on Earth. Not only does this point to the comet being formed in a much colder – likely around -243ºC – environment than found within our solar system, it was also subject to very little in the way of stellar radiation, suggesting it formed at the very outer edge of its originating star system.

Further, as it passed around the Sun and was at its most active, the comet started outgassing more and more methane. This led to the theory that in its passage towards the Sun and the initial formation of its coma and tail, 3I/Atlas had shed the last of its cosmic ray irradiated outer shell, allowing its more “pristine” (i.e. preserved from the days of its formation) inner layers to be exposed to sublimation. In particular the abundance of methane being released further underlined the idea that the comet had formed in an extremely cold environment.

This is important because it directly impacts our understanding of the formation of stellar systems. These generally hold that star systems are born of relatively “hot”, compressed clouds of dust and gas, the majority of which collapses under gravity to form the central star, with any planets, asteroid, comets and such like forming in the immediate aftermath of the star igniting, when the “left over” material is still relatively dense – and warm – as it surrounds the newly-born star. Thus, 3I/Atlas potentially hints at an alternative path of stellar evolution we have yet to identify and understand.

Artemis Update

Following-on from my previous Space Sunday piece, the core stage of the Space Launch System (SLS) rocket that will be used in 2027’s Artemis 3 mission, completed its 1,450 kilometre journey by canal, river and sea from NASA’s Michoud Assembly Facility in New Orleans to the turn basin at Kennedy Space Centre’s (KSC) Complex 39 on April 27th, 2026.

The stage, lacking its four RS-25 engine units, which will installed as vehicle stacking starts within Kennedy’s Vehicle Assembly Building (VAB) reach the wharf in the basin safely aboard the Pegasus transport barge. Following its arrival, on April 28th, the stage was transferred by road from the basin to the VAB in readiness for vehicle stacking to commence.

*The NASA transport barge* Pegasus is manoeuvred by its tug in readiness for mooring at the Complex 39 wharf at Kennedy Space Centre. Within it sits the core stage of the SLS booster to be used on the Artemis 3 mission scheduled for 2027. Credit: NASA

At the same time as the stage was arriving at KSC, it was confirmed that Artemis 3 – planned as a crewed test of the available lunar lander vehicles required for missions to the surface of the Moon – has been pushed back from mid-2027 to an October-November 2027 time frame. This is apparently to allow both SpaceX and Blue Origin, the two contractors charged with supplying NASA with crew-capable lunar landers, with more time to have their first vehicles ready for testing in Earth orbit.

Whilst NASA is playing down the pushback, there is already mounting feeling in some circles that the mission will ultimately be pushed back until early to mid 2028, simply because there will not be any lander vehicle ready for Earth-orbit testing by a crew by late 2027.

On April 28th, 2026 NASA also released the first image of the heat shield used on the Artemis 2 mission to project the Orion capsule from the searing heat of re-entry into Earth’s atmosphere at the end of the mission.

As regular readers will know, there was considerable concern surrounding the heat shield after an identical unit used on the uncrewed Artemis 1 mission in December 2022 showed unexpectedly high levels of damage. Investigations revealed the worst of this damage – deep pits and holes within the ablative material of the heat shield were the results of gasses trapped in the layer being super-heated as the spacecraft “skipped” through the atmosphere before fully re-entering, resulting in them “blowing out” sections of the heat shield’s layers as they violently expanded.

As a result of this, the heat shields to be used from Artemis 3 mission onwards were put through a redesign prior to fabrication, but the shield for Artemis 2 had already been manufactured and installed – so the re-entry profile for the mission was changed in order to reduce the risk of outgassing and damage to the heat shield. Even so, fears remained as to the shield’s fitness for purpose.

Clearly it was up to the task as evidenced by the successful return to Earth by Artemis 2 crew, and within the image released by NASA on April 28th, it is clear that the heat shield more then withstood the stresses of the revised re-entry profile – even if the image is itself a most unusual one.

The Artemis 2 heat shield – scorched and lightly scored but in far better shape that the heat shield from Artemis 1 – as seen from underwater as the Orion capsule to which it is attached awaits recovery following its splashdown in the Pacific Ocean after a successful mission. Credit: US Navy

So keen were NASA engineers to see the state of the heat shield, that even as the Orion capsule floated in the Pacific Ocean off the Californian coast, and the crew were being recovered, a camera-equipped US Navy diver was tasked with swimming under the capsule and photographing the heat shield from below. The result is a somewhat eerie, almost sci-fi like underwater image of the heat shield, streaked with burn and ablation marks across its entire surface – as would be expected – but without any of the deep chadding and pitting seen on the Artemis 1 heat shield.

Obviously, the heat shield, recovered with the rest of the capsule and now back with NASA, will be examined more thoroughly, but this initial picture finally put to rest concerns that the Orion heat shield might be somehow, and potentially fatally, flawed.

Space Sunday: Curiosity’s discoveries and some updates

Posted on April 26, 2026 by Inara Pey

It’s been a good while since I offered any updates on the work of NASA’s Curiosity rover on Mars, which is a bit of a shame given it was my reporting on Curiosity’s arrival and mission on Mars which eventually morphed into Space Sunday.

Curiosity is now 13 years and eight months into its mission on Mars (over 14 years since its launch from Earth), and it is still going strong. Such is the amount of data still being returned by the rover’s exploration of Gale Crater and, specifically, the great mound of Aeolis Mons at its centre (which NASA unofficially calls “Mount Sharp”), Earth-based review and analysis of its findings is running somewhat behind.

Take two papers on Curiosity’s findings published in April 2026, for example. They relate to data gathered by Curiosity in 2020 and 2022. However, their individual findings both confirm elements of our understanding of Gale Crater’s history and open the door to some intriguing possibilities when it comes to past microbial life on Mars.

The first paper, Diverse organic molecules on Mars revealed by the first SAM TMAH experiment, examines the data gathered by the rover in 2020 whilst examining a rock sample on the slopes of “Mount Sharp” scientists had dubbed “Mary Anning”. This examination revealed the clay-bearing sandstone rock contained no fewer than 21 organic compounds, seven of which had been detected for the first time. Together, they stand as the single largest and most diverse collection of organic compounds to be found in one location on Mars.

To be clear, “organic compounds” should not be taken to mean “evidence of life” – organics can be formed through inorganic processes as well as organic ones. Further, exactly what caused the formation of these compounds in so close proximity to one another is unknown; whilst they could be the result of mineral and chemical interactions with rock, they equally might have been deposited on “Mount Sharp” as a result of a meteorite impact; we just don’t know.

*The “Mary Anning” rock, the site of the discovery of more than 20 organic compounds – including seven never previously encountered on Mars. Image via* Curiosity’s *MastCam. Credit: NASA / JPL*

However, what is interesting about these compounds is the fact that they were detected within a surface rock that has been around perhaps for 3.5 billion years, despite the rock being bombarded by solar radiation and subject to wind erosion, etc.. This alone suggests that whilst overwhelmingly hostile to biological processes we’re familiar with, Mars could preserve the biosignatures of any Martian microbes which might have once been present on the planet.

In this regard, the samples gathered and analysed by Curiosity have been shown to contain methyl benzoate. A complex compound often associated with organics (but again can be formed by both organic or inorganic processes); the fact that such a complex ester group compound is present within the rock does strengthen the argument that Mars might yet preserve evidence of past life on Mars.

What’s more – and again with the inorganic / organic caveat – the team behind the paper confirmed the samples taken from “Mary Anning” contains nitrogen heterocycles. These are rings of nitrogen-bearing carbon atoms which here on Earth are considered precursors of RNA and DNA. All of which adds up to a remarking set of findings.

*Mapping the Amapari Marker on “Mount Sharp”. Credit: NASA / JPL*

The second paper, Amapari Marker Band Metal-Enrichments: Potential Mechanisms and Implications for Surface and Subsurface Water and Weathering in Gale Crater; examines the case for water in Gale Crater using the “bathtub ring” of the Amapari Marker.

The latter is a boundary layer extending for tens of kilometres around the upper reaches of “Mount Sharp” to the point of being visible from orbit using the right equipment. It is believed to form the boundary between the upper limits reached by waters which had formed multiple lakes within the crater during the planet’s warmer, wet periods of its early history, and the upper portion of “Mount Sharp” which was never immersed in water.

Within the Amapari Marker, Curiosity found deposits of compounds and – particularly – metals which were deposited en masse, so to speak, as the waters retreated back down into Gale Crater after reaching this highest point of their extent. Hence the term “bathtub ring”: the Amapari Marker might be thought of as resembling the ring of grime left around the sides of a bathtub once the water has been drained following a particularly mucky bath.

*Various views of the Amapari Marker. A-C captured via* Curiosity’s *MastCam, D-I captured via the MALI imager on the rover’s robotic arm using true colour, monochrome and false colour filters (to highlight deposits in the rocks). Credit: NASA / JPL*

Such banding or layer markers are common on Earth as well, and are referred to as redox (REDuction OXidation) reactions. These have been shown to create metals such as iron, zinc, manganese and similar precipitate out of water – which are exactly the irons found in the Amapari Marker in Gale Crater. Thus, not only does this further demonstrate the likeliness that Gale Crater was one home to lakes of considerable depth (“Mount Sharp” is some 5 kilometres high, with the walls of the crater reaching similar heights, allowing for lakes of at least a kilometre or two in depth), it also suggests the potential for the lake to potentially having been inhabitable by Martian microbes.

This is because microbes can mediate redox reactions, and in some cases create thicker deposits than abiotic reactions; deposits that could be even more useful as a source of energy for subsequent colonies of microbes. However, this is, again, only a supposition; there are many questions about the overall conditions within Gale Crater still to be answered. These include matters of Water-to-rock ratios, lake depth, and atmospheric concentrations of O2 during transient events; all make it extremely difficult to draw any single conclusion relating to the lakes in the crater, the deposits found within the Amapari Layer what various combinations of the answers to these questions (if they could be answered) it might mean for the ancient habitability of Mars.

Even so, the findings of these papers again demonstrate how intriguing Mars is.

In Brief

New Glenn Update

In my previous Space Sunday article, I covered the semi-successful Blue Origin NG-3 launch – the third flight of the impressive New Glenn heavy-lift launch vehicle, together with the recovery of the first stage Never Tell Me the Odds as it made its second flight (albeit with new engines). The mission was semi-successful as the upper stage of the booster suffered an anomaly which stranded the BlueBird 7 communications satellite payload in the wrong orbit.

*April 19th, 2026: New Glenn NG-3 climbs away from its launch pad at Space Launch complex 36, Canaveral Space Force Station, Florida. Credit: John Raoux*

Due to the failure of the upper stage, and as expected, on April 22nd, 2026, the US Federal Aviation Administration (FAA), which oversees commercial launch operations in the US, announced that New Glenn is grounded until a Blue Origin-led investigation can determine the root cause of the issue.

In this, Blue Origin is already a little ahead of the curve: during the NG-3 mission, telemetry indicated that during an initial burn of the upper stage’s engines, one of the two BE-3U motors failed to produce sufficient thrust for the burn to be properly completed, and as a precaution against total vehicle and payload loss, the burn was curtailed and the second required engine burn cancelled, thus leaving BlueBird 7 stranded in the wrong orbit.

The question now is whether the issue with the BE-3U motor is something restricted to that particular motor or something endemic to the entire production of BE-3Us. Determining this, and what – if anything – needs to be done to fix issue, will determine how long New Glenn remains grounded.

*An infographic on the BE-4 and BE-3U engines used on New Glenn. credit: Blue Origin*

Getting the matter sorted is a priority for Blue Origin. They have four more New Glenn launches planned for 2026. Two of these are commercial (which could slip somewhat easily) and two government-related. One of the latter is a “rideshare” mission of several payloads (NG-7), including a technology demonstrator for the National Reconnaissance Office (NRO). This had been due to launch almost a year ago on a Firefly Alpha rocket, but the NRO opted to move it to another launch vehicle when in April 2025, Firefly suffered its fourth full or partial failure in just seven launches. As such, the NRO might again get nervous if New Glenn is subject to an extended grounding.

More importantly for Blue Origin is the NG-5 launch. This is slated to carry the company’s Blue Moon Pathfinder lander mission to the Moon. Pathfinder, as I’ve noted in past Space Sunday pieces, is a critical demonstration of significant technologies to be used within both Blue Origin’s Blue Moon Mark 1 and Mark 2 cargo / crew lunar landers. As such, any significant delay in its flight could have repercussions for the Blue Moon lander programme as a whole at a time when both Blue Origin and SpaceX are under pressure from NASA to demonstrate they can have human landing systems available to meet the planned Artemis 4 mission of 2028.

NASA: Artemis 3, OIG Concerns and Budget Fight-Back

NASA’s Michoud Assembly Facility in New Orleans, home to the Space Launch System (SLS) production line, rolled out the core stage of the booster that will launch the Artemis 3 mission to Earth orbit in 2027.

Containing the liquid hydrogen tank, liquid oxygen tank, intertank, and forward skirt, the core stage is the bright orange element of the SLS, which at its upper end will be fitted with the stage adaptor for the ICPS upper stage, and at its lower end, the four RS-25 motors that will power the course stage and their housing. Its roll-out at Michoud marks the start of its journey by barge to Kennedy Space Centre, Florida, where it will be integrated with the rest of the 3elements required for the mission, including the Orion Multiple-Purpose Crew Vehicle which will contain the crew for the mission.

*The core stage of the SLS rocket destined to launch the Artemis 3 mission is rolled-out from the NASA Michoud Assembly Facility in New Orleans,* sans *it four RS-25 engines, at the start of its journey to Kennedy Space Centre. Credit: NASA*

Artemis 3 was originally going to be the first lunar landing mission for Project Artemis, however, earlier in 2026, the mission was re-targeted as an Earth-orbital test of one or both of the proposed crewed landing craft being developed by Blue Origin and SpaceX, and assess whether either / both are fit for purpose ahead of any lunar-focused missions; as such it is a crucial stepping stone for Artemis.

In this, the roll-out of the new SLS core stage is seen by NASA as a sign that it is on course to meet its current Artemis schedule: orbital HLS testing in 2027 and first crewed landing in 2028. However, the agency’s own Office of Inspector General (OIG) sees things differently.

On April 20th, the OIG – responsible for overseeing all of NASA’s activities in terms of fiscal responsibility, preventing mismanagement, identifying project shortfalls, and generally auditing NASA programmes in terms of their overall progress / readiness – issued a further report indicating that the Artemis programme is once again at risk of delay due to continued issues with the development of the new spacesuits Artemis crews are to use on the surface of the Moon.

*An early version of the NASA / Axiom lunar space suit in 2024. This suit has now undergone numerous revisions – including that of colour. Credit: Axiom*

Work on the new suits – those currently in use aboard the International Space Station, whilst derived from the Apollo space suits, are unsuitable for lunar use – commenced in the 20-teens and has largely been a source of embarrassment to NASA. Just after the first prototype suit was revealed to the public to much fanfare in 2019, it was found to be unfit for purpose and abandoned.

In 2022, NASA contracted veteran space suit manufacturer Collins LLC (responsible for both the Apollo and ISS space suits) and newcomer Axiom to develop new space suits – but with a twist: the new suits would have to be capable of sustained operations on the lunar surface and also – through the integration of different components / elements during the manufacture of specific suits – for use on the ISS.

Although this sounded reasonable, it actually caused Collins LLC to drop out of the contract in 2024 due to complexities involved in developing such a suit system in a relatively short time frame. Axiom has continued its own suit development, and has offered a number of positive-sounding updates on progress. However, according to the OIG report, the reality with the Axiom suit is somewhat different: it is already running two years behind schedule, in part due to the requirement for the same basic suit having to be adaptable for two very different uses, and now looks likely to slip a further year, meaning it will not be ready for use until 2031.

Both NASA Administrator Jared Isaacman and Axiom offered statements countering the OIG report when it appeared, restating commitments to the 2028 crewed landing. However, the OIG has a track record of being far more accurate in its assessments of the readiness of projects than NASA in meeting target dates for those same projects. As such this report could come back to bite NASA if it proves accurate.

In the meantime, the battle over NASA’s future budget has once more ignited. As I’ve previously reported, in 2025, the Trump Administration sought to reduce NASA’s modest budget by 23% in 2026, including cutting the agency’s science budget by 47%. Ultimately, the House and the Senate rejected such a drastic cut – so the Trump Administration has now simply added the same cuts to its planned 2027 fiscal year budget. In response, the House and Senate – and on both sides of their respective aisles are once again pushing back.

Both the president and Congress have provided explicit direction for NASA to undertake a range of activities, from exploration and science to aeronautics research. We must ensure that NASA is funded at a level that allows it to pursue those missions. I simply do not believe that this budget proposal is capable of supporting what President Trump himself has directed the agency to accomplish over the course of his two terms, nor what Congress has directed by law.

– Rep. Brian Babin (R-Texas), chair man, U.S. House of Representatives’ Committee on Science, Space, and Technology, April 22nd, 2026.

Babin, with the support of Democrats and Republicans on his committee goes on to point out that while American’s spiralling national debt of some US $38.889 trillion or US $116,065 per US citizen (and in a good part fuelled by the fiscal / foreign policies of the current Administration) is of major concern, cutting NASA’s budget amounts to mere “penny-pinching” than it does speak to an attempt to reign-in spending, and is a move that will further damage US leadership in science and technology.

Space Sunday: Never Tell Me the Odds, Rosalind Franklin and a Health Update

Posted on April 19, 2026 by Inara Pey

*Captured via a drone, NG-3’s Never Tell Me the Odds edges towards Blue Origin’s Landing Platform Vessel Jacklyn, April 19th, 2026. Credit: Blue Origin*

Even as this article was being prepped, my eyes were glued to the screen watching the launch of Blue Origin’s NG-3 mission, the third flight of the company’s mighty New Glenn Heavy Lift Launch Vehicle (HLLV) and the first re-use of a New Glenn first stage – that of Never Tell Me the Odds, which was previously flown as a part of the NG-2 mission in November 2025.

NG-3 had originally been slated for the launch of Blue Origin’s Blue Moon lunar lander Pathfinder mission, which the company had originally targeted for a January / February 2026 launch. However, that mission will not now occur until mid-to-late 2026, so NG-3 was reassigned to a commercial launch, that of AST SpaceMobile’s BlueBird 7 cellular broadband satellite. Between NG-3 and the launch of Blue Moon Pathfinder, New Glenn will also serve as the launch vehicle to deliver 48 Amazon LEO (formerly Project Kuiper) to low Earth orbit as a part of Amazon’s LEO internet constellation.

*An external camera on New Glenn looks down the length of the booster’s first stage towards Launch Complex SL-36, Cape Canaveral Space Force Station, 30 seconds after launch. Credit: Blue Origin*

Both the NG-3 and NG-4 launches are cause of mixed emotions. In its own right, New Glenn is a remarkable vehicle, capable of delivering up to 45 tonnes to low Earth orbit with the first stage recovered – just five tonnes less than SpaceX’s Falcon Heavy with its three core elements recovered. As such, and given its recovery is – broadly speaking – less complex than Falcon Heavy, it stands to make itself felt as a highly flexible launch platform capable of meeting both commercial and government launch requirements (as has already been demonstrated in the vehicle’s first 2 flights, including being certified for launching classified payloads).

On the negative side, NG-3 and NG-4 are both increasing the levels of satellites orbiting close to Earth together with the overall light pollution they cause for astronomers, whilst simultaneously increasing the risk of on-orbit collisions between satellites. And that’s to say nothing of the added atmospheric pollution such satellites cause when they reach the end of their (relatively short) life spans and are dumped back into the atmosphere to burn-up.

In this, AST SpaceMobile have been particularly cavalier. Whilst the likes of SpaceX (Starlink) and Amazon (Amazon LEO) have at least paid lip service to requests to reduce the amount of light pollution their satellites produce and seriously disrupts a wide range of astronomical work, AST SpaceMobile has essentially lifted a middle finger to such requests, working on generations of ever-larger and more polluting satellites. The 6-tonne BlueBird 7 for example, is not only far bigger than Amazon LEO / Starlink satellites (although its family of satellites will be far smaller than the Amazon / Starlink constellations), it and its siblings have massive solar arrays covering 223 sq metres (2,400 sq ft), which can make them brighter than any star seen in the sky.

*New Glenn NG-3 captured from an airborne camera as it climbs towards first stage Main Engine Cut-Off. Credit: Blue Origin*

NG-3 lifted-off from Launch Complex-36 (LC-36) at Cape Canaveral Space Force Station in Florida a little later than its target launch time of 10:45 UTC, rising into the sky at 11:25 UTC. Lift-off mark the first time the New Glenn system has lifted a fully private payload into the sky. As appears common with New Glenn Launches, the vehicle initially held on the pad for a second or so after the countdown reached zero as the seven BE-4 engine powering it all came up to full thrust, then the vehicle seemed to rise ponderously into the air, taking some 17 seconds to clear the height of the lightning towers around the pad.

Thirty seconds into the flight the 98-metre tall rocket completed its roll-over (or “pitch over”) onto to its climb trajectory to orbit. At 1 minute 29 seconds, and climbing through 10.3 kilometres altitude, New Glenn passed through “Max Q”, the period of maximum dynamic pressure, and accelerated through Mach 2 shortly after, entering the cloud base and it did so and becoming obscured from view.

*A camera within the engine bay of New GlennNG-3’s upper stage captures stage separation, with the upper stage powering away from the first stage. Credit: Blue Origin*

Three minutes into the flight and the rocket reached MECO – main engine cut-off – for the first stage motors at an altitude of 77.5 km. Stage separation followed quickly thereafter, together with the ignition of the two BE-3U motors on the rocket’s payload carrying upper stage, allowing it to both continue its ascent towards obit and power itself away from the first stage, jettisoning the payload fairings as it did so to expose BlueBird 7 to space.

Controlled via the fins along its side, Never Tell Me the Odds continue upwards unpowered, until it reached apogee, then became a controlled descent through the upper atmosphere, falling on a trajectory that would intersect the position of the Landing Platform Vessel Jacklyn some 600 km off the coast of Florida, so it could attempt a landing.

Never Tell Me the Odds gliding down through the lower atmosphere ahead of firing three of its motors to slow it for landing. Credit: Blue Origin

Seven minutes after launch, three of the first stage BE-4 engine ignited so 20 seconds to both bring Never Tell Me the Odds to a more upright orientation and to cushion its entry into denser atmosphere. The descent continued with the booster again “tipped” over and falling engines-first, passing through “Max Q” some 8 minutes and 20 seconds post-launch, and at T +8:53 three BE-4s again re-lit, powering the booster down over the waters close to Jacklyn, before the motors cut to just one, allowing the booster to crab sideways over the landing deck and execute a perfect touchdown.

During this time, the second stage complete its initial burn to reach orbit before shutting down for a period, prior to a final engine burn to deliver the payload to its intended orbit. This second firing of the BE-3U motors apparently failed, leaving BlueBird 7 in an off-nominal orbit following separation from the upper stage, as both Blue Origin and AST SpaceMobile looked at the issue.

*Never* Tell Me the Odds sits on the deck of the Landing Platform Vessel Jacklyn, auto-welded in place, post-landing. Blue Origin

SpaceX to Launch Rosalind Franklin to Mars

It has been announced that SpaceX will now launch Europe’s much-delayed Rosalind Franklin (aka the ExoMars rover) to Mars in 2028 – almost 28 years after the mission was conceived.

Originally, ExoMars (as it has been known for most of its life) was due to be a partnership mission with NASA’s MAX-C rover, only for the latter to be cancelled. As a compensatory measure, NASA offered to launch both the ExoMars rover and Europe’s Trace Gas Orbiter (TGO), which had been folded into the “ExoMars” banner, to Mars aboard two Atlas V boosters, with TGO launching in 2016 and ExoMars in 2018. However, this offer was again rescinded due to NASA budget cuts, leaving the European Space Agency looking for a new partner – and finding one in the form of Roscosmos.

*A test vehicle for* Rosalind Franklin seen from the rover’s front in a low angle, emphasising the drilling mechanism. Credit: ESA

This at least allowed TGO to launch in its planned year of 2016, but saw a delay in the launch of the rover, as Russia had to develop a special landing platform for it, and wanted that platform to be science-capable. Coupled with issues with the rover’s parachute system, these delays eventually hit the COVID-19 wall, and the launch was further delayed. Then Russia invaded Ukraine, and all bets were off; ESA now needed another partner to get (the now renamed) Rosalind Franklin to Mars. NASA once again stepped up – but this time, instead of offering to launch the mission, they indicated they would find a suitable launch vehicle supplier in return for ESA flying some of their own equipment on the mission.

On April 16th, 2026, this arrangement resulted in NASA and ESA announcing that SpaceX had been selected as the mission’s launch vehicle provider, and that a Falcon Heavy would be used to send the rover on its way to Mars.

*An artist’s impression of* Rosalind Franklin deploying from its European landing platform. Credit: Aerotime.aero

Rosalind Franklin sits between the NASA solar-powered Mars Exploration Rovers (MERs) and the current nuclear-powered Curiosity-class rovers in size, whilst retaining the former’s solar power system. Despite its boxy, almost amateurish looks, Rosalind Franklin is one of the most science-capable vehicles to be sent to Mars, carrying eight scientific instruments, all designed to aide its primary mission of seeking subsurface bio signs. It will also carry a sample-gathering drill system capable of penetrating up to 2 metres below the planet’s surface.

The landing site for the mission is Oxia Planum, a 200 km-wide clay-bearing plain in the planet’s northern hemisphere, some 18º above the equator. It is one of the largest exposed clay-bearing deposits on Mars and is believed to be some 3.6-4 billion years old. There is ample evidence for free-flowing water having once existed within the region, with the exposed rocks exhibiting different compositions, indicating a variety of deposition and wetting environments.

If the current arrangement holds, Rosalind Franklin will be launched around mid-to-late 2028, and arrive on Mars in 2029.

Cause of Medical ISS Evacuation Revealed

Back in January I covered the emergency evacuation of NASA’s International Space Station (ISS) Expedition 73/74 (aka. NASA / SpaceX Crew 11) after one of the crew experienced a medical issue. At the time, the details of the individual experiencing problems, and what those problems might be were not made public – standard NASA practice. However, all four of the crew were returned to Earth aboard their SpaceX Crew Dragon vehicle out of an “abundance of caution” – and because leaving two of them behind would have left them without a ride home in the event of a further emergency.

The Expedition 73/74 crew comprised JAXA (Japan Aerospace Exploration Agency) astronaut and Mission Specialist Kimiya Yui, Roscosmos cosmonaut and Mission Specialist Oleg Platonov, veteran NASA astronaut Michael “Mike” Fincke – who had assumed the role of ISS mission commander not long after the crew originally arrived at the space station, and NASA astronaut Zena Cardman, who served as mission commander for the Crew 11 flight to the ISS. At the time the medical situation initially occurred, Fincke and Cardman were going through various checks of themselves and equipment in readiness for an upcoming EVA – extravehicular activity “spacewalk” to work on preparing the stations’ power system for the installation of further iROSA solar arrays to further boosts the ISS’s electrical power production.

Given this EVA prep work was underway, and NASA then called off the EVA as a whole, initial speculation was that either Fincke or Cardman had suffered some form of medical emergency. However, attention shifted to JAXA astronaut Yui after it was revealed he sought a private consultation with NASA medics on Earth at the same time the EVA preparation work was in progress.

As it turned out, the speculation about Fincke and Cardman was correct when, on February 25th, Fincke decided to go public and reveal he was the one with the issue – although at the time, he declined to indicate exactly what the issue was, and did not do so for a further month.

At the end of March 2026, 58-year-old Fincke, who had previously flown on ISS missions Soyuz TMA-4 (ISS Expedition 9), Soyuz TMA-13 (ISS Expedition 18), and STS-134, and who had been initially picked to fly a 3-person Crew Flight Test of Boeing’s Starliner before that mission was reduced to just two crew – “Butch” Wilmore and “Suni” Williams), revealed that just after the EVA prep work had ended ahead of schedule and the entire ISS crew were settling down for dinner, he suddenly lost his voice.

It was just amazingly quick. Out of the blue. My crewmates definitely saw that I was in distress. It was all hands on deck within just a matter of seconds.

– Michael Fincke, describing the episode which led to his crew being evacuated from the ISS

As several of the ISS crew sought to assist Fincke, Yui got onto a private channel with Mission Control to relay the situation to the ground-based medical team. The episode lasted some 20 minutes before Fincke recovered his voice, and throughout that time he was not in pain or suffering any other symptoms. However, the medical team on Earth could not rule out the potential that he has suffered some form of stroke or heart attack – or that contaminants in the food could have caused his issue and might do so again to himself or another crew member.

It was because of these latter aspects that the decision was made to curtail the crew’s mission to the ISS a month early and return them to Earth, where all of them were subjected to a range of tests, not of which has apparently uncovered any underlying cause for Fincke’s episode or given rise to any concerns over the health of the other three. Fincke himself, as recently as mid-April has stated he has never suffered anything like the loss of voice either before or since the episode on the ISS, and he is hoping to make a full return to flight status for future missions.

Space Sunday: Artemis 2: around the Moon, home again – and beyond!

Posted on April 12, 2026 by Inara Pey

We see you: Christina Koch looks out of one of the Orion capsule’s windows towards a GoPro camera mounted on one of the four forward-swept solar array wings of the vehicle’s European Service Module (ESM). To her right, she is holding aloft the mission’s zero-gee indicator / mascot, “Rise”. Created by a 3rd grader, “Rise” has a smiley-faced Moon and is wearing a blue-and-green cap representing Earth, all in a homage to the famous Apollo 8 “Earthrise” photo. Credit: NASA

On Wednesday April 1st, 2026, NASA’s Artemis 2 mission launched on a 10-day cruise to the Moon and back (with time initially spent in Earth orbit), carrying a crew of four to test the capabilities and facilities of the Orion Multi-Purpose Crew Vehicle (MPCV). The mission was a key preparatory step to send crews to the surface of the Moon, starting with the flight of Artemis 4, currently targeting a 2028 launch.

In the first part of this 2-part series I covered Artemis 2 from launch to TLI. Here I complete the voyage in summary form.

Whilst marked by a number of on-going space health experiments, video calls to Earth and performing sundry tasks and s few minor fixes, the outward trip from Earth to the Moon was pretty much a claim affair. A 17.5 second mid-course correction manoeuvre was performed automatically by Integrity, the Orion spacecraft, on mission day 5 – which was actually the first to be performed, the initial correction burn having been cancelled due to Integrity being so precisely on course whilst under its own flight control software.

*Taken in high Earth orbit, this image shows the European Service Module and its main engine, with the Earth as a backdrop as the motor is test gimballed ahead of the TLI burn to send* Integrity *to the Moon. Captured by a solar-panel mounted GoPro camera. Credit: NASA*

Day five also saw the crew test their dual-purpose Orion Crew Survival System (OCSS) suits – the orange-coloured space suits the crew wore during the Artemis 2. Designed for quick donning, the suits function as a contingency safety system during the crew’s time aboard and Orion spacecraft, providing up to 144 hours of life support in the event of a cabin depressurisation.

*Artemis 2 astronaut Christina Koch poses in her custom-made OCSS suit ahead of the Artemis 2 mission. Credit: NASA.*

In their second role, the suits are intended to act as water survival suits in the event of an emergency evacuation of an Orion vehicle post-splashdown. In this role, the suits are intentionally coloured “international orange” so as to be more clearly visible in the water – just like survival suits used on ocean-going cargo vessels, oil rigs, deep sea fishing vessels, etc They additionally have inbuilt flotation devices. Each OCSS is custom made to fit an individual astronaut.

Day five also saw a series of discussions with Mission Control on the upcoming loop around the Moon to review lunar surface targets for observation and photography during the flyby and finalise observation techniques.

On flight day 6, Integrity officially entered the influence of the Moon, with lunar gravity now the dominant force in shaping the vehicle’s trajectory. Until now, Integrity had effectively (if slowly) been decelerating, due to the “pull” of Earth’s gravity behind it, effectively cruising at a few thousand kilometres an hour at it approached the Moon. Now, under the Moon’s influence the craft would start to very slowly accelerate, allowing the Moon’s gravity to swing it around the Moon and lob it back towards Earth without any significant engine burns.

Around the Moon

At 23:00 UCT on April 6th, Artemis 2 made its closest approach to the Moon, passing some 6,545 kilometres above the Moon’s far side. Shortly thereafter Integrity reached a distance of 406,771 kilometres from Earth, breaking the record for the furthest any humans had been from Earth and set by the crew of Apollo 13 in 1970. At this point, Integrity officially started its flight back towards Earth.

During the loop around the Moon, Artemis 2 was in communications black-out with Earth due to the bulk of the Moon being between the spacecraft and Earth, effectively blocking all signals. This blackout lasted 40 minutes, and ended with a successful recovery of comms and telemetry at the expected time.

*A gif showing the solar eclipse as seen from deep space by Artemis 2. Credit: NASA*

Following the comms blackout, the crew of Artemis 2 witnessed a solar eclipse from deep space as the bulk of the Moon came between them and the Sun. This allowed the crew to observe both the eclipse from a unique perspective, and witness a number of “impact flashes” of meteoroids striking the semi-dark lunar surface facing them. The Moon was not fully dark as the Earth was off to one side relative to Integrity, and so was reflecting sunlight back onto one hemisphere of the Moon, bathing it in “Earthlight”.

Also during the flight around the Moon, the crew christened two previously unnamed craters on the Moon. They named one for their spacecraft, Integrity, whilst the second was – in a poignant moment – named Carroll, in honour of Reid Wiseman’s late wife, who passed away from cancer in 2020.

*Artemis 2 crew Commander, Reid Wiseman with his late wife, Carroll, after whom the crew named a crater on the Moon.*

Between flight day 7 and flight day 9, Orion departed the Moon’s sphere of influence on its free return trajectory towards Earth, once again slowly accelerating. For most of Day 7 the crew were engaged in debriefing calls with Earth, recording their observations, feelings and emotions during their trip around the Moon whilst memories and reactions were still fresh. They also put in a call to astronauts aboard the International Space Station (ISS).

A further planned use of manual control by Wiseman and Pilot Victor Glover on Day 8 was cancelled in order to allow mission managers conduct a data-gathering exercise related to a non-critical helium leak within the Orion’s European Service Module (ESM), so that they might better analyse the issue post-mission. Two final trajectory adjustment burns were carried out on Days 9 and 10, lasting 8 and 9 seconds respectively. Most of Day 9 saw the crew packing and stowing experiments and equipment in readiness for re-entry and splashdown.

Following the course correction burn on Day 10, the ESM was jettisoned, its work done. The reaction control thrusters system (RCS) on Integrity then operated in sequence over 19-seond period, both manoeuvring the capsule away from the ESM and orienting it in readiness foe atmospheric re-entry.

*A gif showing solar panel GoPro camera views of* Integrity’s *crew capsule sparating from the European Service Module in readiness for re-entry. Credit: NASA*

EDS: Entry, Descent and Splashdown

Day 10 saw the most critical elements of the mission unfold: atmospheric entry, descent and splashdown. During Artemis 1, and as I’ve covered in numerous Space Sunday pieces, post-recovery, the heat shield showed some disturbing issues. As well as the expected ablation damage to the heat shield, it also showed signed of deep scoring and charring, with relatively large holes apparently seared through the heat shield material.

After extensive analysis, it was determined that an error in the fabrication process for the initial heat shields for Artemis 1 through 3 had resulted in pockets of gas being trapped in the layers of ablative material. Due to the original re-entry profile for Orion, as used on Artemis 1, which saw the vehicle “skip” in and out of the upper atmosphere to reduce its velocity prior to actual re-entry, these gases ended up being super-heated several times, weakening the heat shield’s structure and eventually blowing holes up and out of it as they outgassed.

While the fabrication process for the heat shields was revised to mitigate any issues of gases becoming trapped – Artemis 2, due to time constraints, would have to fly with its original heat shield. To compensate for this, NASA altered the mission’s re-entry profile to be more Apollo-like: a single direct re-entry. Whilst this might increase stresses on the vehicle and crew, it would reduce the time over which any trapped gases in the heat shield might have expand and contract and weaken its overall integrity, thus increasing the risk of failure.

As it turned out, the heat shield (subject to post-flight inspection) did its job in this new re-entry profile and protected Integrity and its crew, all of which descended by parachute post re-entry to splashdown off the coast of California, where a recovery operation overseen by the USS John P. Murtha out of San Diego saw the recovery of both crew and the space vehicle. Following initial medical checks on the Murtha, the four crew were then flown to the mainland for further check-ups, prior to proceeding on to the Johnson Space Centre in Texas to be reunited with families and loved ones.

The Artemis 2 crew at Johnson Space Centre, April 11th, 2026. (l to r): Jeremy Hansen (CSA); Christina Koch (NASA); Victor Glover (NASA) and a triumphant-looking Reid Wiseman (NASA), holding “Rise” the mission’s zero-gravity indicator and mascot. Credit: NASA

Research related to Artemis 2 will continue post flight, and some of it will continue to focus directly on the four crew, comprising functional check-out tests, simulated space walks, exercises, etc., to further gain insight into the human body’s ability to adapt to low gravity operations and work, and its ability to recover from them. As well as this, all four will be a part of a media circus for some time to come. To them, and all those involved in Artemis and Artemis 2 – congratulations.

What Comes Next?

Originally, Artemis 2 was to be followed by the first attempt at landing an Artemis crew on the Moon. However, this idea both spoke to an unwarranted gung-ho attitude on the part of Artemis management at NASA (no crewed pre-testing of the lunar landing system (called the Human Landing System, or HLS) in Earth orbit), and assumed the mission would actually have a lunar landing vehicle (from SpaceX) available to meet its 2027 launch date.

Blue Origin’s Blue Moon Mark 2 HLS (l) and SpaceX Starship HLS – NOT to scale. The Blue Origin vehicle is 16 metres high as benefits a low centre of mass – crew compartment, engines electronics, etc, all at the base of the vehicle, which includes broad-set landing legs for stability. The SpaceX design – 52 metres tall – suffers from a high centre of mass: crew compartment, electronics, batteries, engines all in the upper third of the vehicle, requiring an elevator (single point of failure) to get crews to / from the surface on the Moon, and a comparatively narrow-set landing legs, further increasing vehicle instability when landing on an unprepared surface like the Moon.

In taking over at NASA, Jared Issacman saw the gung-ho approach of Artemis 3 as a step too far, and so – with Congressional and White House approval – determined Artemis 3 should be an Earth-orbiting testy of the HLS vehicle by a crew. Also, in keeping with his predecessor, Sean Duffy, he indicated that SpaceX was no longer the sole provider of the Artemis 3 HLS; but would directly face off against Blue Origin, who had been awarded a HLS contract by order of Congress after NASA changed the scope and rules of the original HLS contract to favour SpaceX.

Given that the SpaceX HLS continues to exist as little more than a few disparate elements (such as the crew elevator – largely developed by NASA) and pretty computer renderings, this move to include Blue Origin – who are actively testing elements of their HLS, Called Blue Moon Mark 2 with NASA astronauts – is a wise one, given the SpaceX CEO appears to believe time frames and delivery dates are purely functions of his ego.

A full scale mock-up of the Blue Origin Blue Moon Mark 2 crew section with airlock undergoing testing for astronaut egress / ingress and the recovery of an incapacitated crew member, using the neutral buoyancy facility at NASA’s Johnson Space Centre. Credit: Blue Origin / NASA

As it is, this year should see Blue Origin fly a Blue Moon “pathfinder” mission to the Moon. This will see a scaled-down version of the Blue Moon cargo lander fly a payload from NASA to the Moon, allowing it to test the flight control, navigation, and data communications systems and avionics which will all be part of both the Blue Moon Mark 1 cargo vehicle and Blue Moon Mark 2 HLS. If successful, the mission could put Blue Origin in a strong position to provide the HLS vehicle for both Artemis 4 and Artemis 5.

However, even if one (or both) HLS vehicles get successfully tested in Earth orbit in 2027, it does not mean NASA will be ready to send astronauts to the lunar surface – there is another hurdle to overcome, one entirely of NASA’s own making: cryogenic orbital refuelling.

To explain: while techniques for transferring hypergolic propellants between space craft has long been available (the ISS, for example, routinely takes on propellants for its manoeuvring thrusters), cryogenic propellant transfer in space is entirely new. It’s not been used before simply because cryogenic propellants are not exactly stable. For one thing, they don’t like heat (and in space, in direct sunlight it s very hot). Heat makes them revert to a gaseous state, expanding their volume. This puts greater and greater pressure on the tanks holding them, such that if the gas isn’t vented to some degree, everything is going to quickly vanish in a brilliant (if silent – in space, no-one can here you go pop!) explosion.

Renderings like this showing one vehicle (in this case a SpaceX Starship (uppermost) transferring propellants to another may look good, but the fact is, such transfers have never been tried in space and are far more complex than hypergolic propellant transfer and storage. Credit: SpaceX

Cryogenic propellants are also heavy in their liquid state, making them somethings of a deadweight if you’re attempting to lift them to orbit rather than burning them as a means to get to orbit. This latter point means that in order just to get to Earth orbit or to the Moon, the SpaceX HLS and Blue Moon Mark 2 (respectively) must launch without the fuel needed to get to the Moon, land a crew and get them back to lunar orbit. Thus, the fuel must be ferried to them post launch.

For Blue Origin, this means launching a Blue Moon HLS to lunar orbit, but without the propellants it needs to operate between lunar orbit and the Moon’s surface. Instead, these must be delivered by a “tanker” craft called the Cislunar Transporter, being developed by Lockheed Martin. But here’s the catch: the Cislunar Transporter has to be launched without the propellants it needs to get to the Moon or those it must transfer to the waiting HLS. So, once in orbit it also has to be “refuelled” by at least two Blue Origin New Glenn rockets.

And if that sounds complicated – SpaceX much do much the same with their HLS, which will launch with only sufficient propellants needed to get to Earth orbit. After this it must either make up to sixteen individual dockings with Starship “tankers” to take on the propellants it needs to reach the Moon and perform its duties there, or it must rendezvous with a (also yet to be built) “orbital fuel depot” previously filled with the propellants it needs by multiple Starship “tanker” flights.

And this is where boil-off comes into play: all of these approaches will result in large volumes of cryogenic propellants spending a lot of time in direct sunlight, turning back to a gaseous state, expanding and requiring venting to prevent their storage tanks rupturing. So techniques and entirely new technologies need to be developed and tested in order to reduce the overall boil-off issues lest more time is spent on “tank top-up” missions than in actually sending humans to the Moon. Further, no-one knows if large volumes of cryogenic propellants can easily be pumped from one vehicle to another in microgravity.

Thus, even though Artemis 2 has been a huge success and NASA is turning its attention to Artemis 3, the programme as a whole still has some hefty hurdles to clear before it is close to being ready to send humans back to the surface of the Moon, and at the current rate of progress, I cannot see all those hurdles being cleared by “early 2028 – less than 2 years from now – when Artemis4 is supposed to launch on its crewed mission to the lunar surface.

Space Sunday: Artemis 2: from launch to TLI

Posted on April 5, 2026 by Inara Pey

Ignition of the four RS-25 engines on the Artemis 2 SLS, several seconds before the ignition of the two Solid Rocket Boosters (SRBs) seen either side of the SLS core stage, take from a protected camera in the base of the Mobile Launch Platform. Credit: NASA

The mission marks a number of firsts for NASA, all critical to future Artemis missions, including:

The first launch of a Space Launch system (SLS) rocket with a crew aboard.
The first launch of the Orion spacecraft – this one christened Integrity by its crew – with people aboard.
The first time an Orion spacecraft has flown under manual control.
The first time an Orion vehicle will attempt a re-entry into Earth’s atmosphere carrying a crew aboard.
The first time humans have surpassed 400,000 kilometres from Earth.
The first time a vehicle intended for use in the vicinity of the Moon has carried an actual toilet on board.
The first time a non-US citizen has travelled to the Moon.

The four crew in question are Mission Commander Reid Wiseman, Mission Pilot Victor Glover, Mission specialist Christina Koch (pronounced “Cook”), all from NASA, and Mission Specialist Jeremy Hansen of the Canadian Space Agency. If you’re interested in potted histories of the crew’s backgrounds, then please refer to my previous Space Sunday article.

Launch

Lift-off came at 22:35 UTC, some 11 minutes later than the target launch time after a couple of minor issues on the SLS vehicle had to be investigated and resolved. One of these related to one of the two battery systems powering the Flight Termination System. The latter is used to destruct the rocket once the crew have been pulled clear by the Launch Abort System (LAS), should a serious issue result in the rocket veering substantially off-course. This particular problem was identified as a sensor failure rather than any fault with the battery itself.

The power of the SLS was immediately apparent following launch – at just thirty seconds into the flight, the launch system has completed its roll to pitch over to the correct ascent angle and was punching through 4.8 kilometres altitude as a speed in excess of 1,920 km/h. From there:

*In just 30 seconds after launch, Artemis 2 was almost 5 kilometres above the Earth and accelerating rapidly. Credit: NASA*

At T+1 minute the vehicle passed through ”Max Q”, the period when the rocket encounters the peak atmospheric dynamic stresses as it continues to accelerate through the denser portion of the atmosphere, the four RS-25 motors of the core stage throttling back to reduce the load on the rocket.
At T+ 90 seconds, with Max Q passed and the RS-25 motors running at 100% thrust, the SLS went supersonic and passing through 22.4 km altitude.
At T+2 minutes, with the RS-25 motors had again throttled to 85% thrust, and the two massive solid rocket boosters, their fuel expended, separated to continue on their own ballistic trajectory, eventually falling into the Atlantic Ocean.
By 3 minutes into the ascent, Artemis 2 was at 78.4 km altitude, and closing on the 80 km Kármán line, the conventional definition of “the edge of space”. Travelling at some 8,000 km/h, the rocket jettisoned the two fairings that had protected Integrity’s European Service Module (ESM).
This was followed almost immediately by the unlocking of the couplings between the LAS at the top of the rocket, and the Orion capsule. The motors on the LAS fired, pulling it clear of the SLS, exposing the Orion capsule to space.

Captured via a film camera mounted on one of NASA observation aircraft, this still shows the SLS rocket of Artemis 2 with its main engines running at full power, together with the separated Solid Rocket Boosters, ESM protective Fairings and the LAS tower, as they part company from the rocket to commence their destructive falls into the Atlantic Ocean. Credit: NASA – Click for full size

MECO – main engine cut-off – occurred at 8 minutes 2 seconds after lift-off, with Integrity and the Interim Cryogenic Propulsion Stage (ICPS) continuing to ascend, the reaction control systems (RCS) on the ICPS sufficient to pull it and Integrity clear of the SLS core stage, which, like the SRBs, continued on its own ballistic trajectory, prior to starting a long fall back to Earth, breaking up in the process and falling into the Atlantic Ocean.

At this point, Integrity was travelling at 27,200 km/h – slightly above the speed required to achieve Earth orbit and on a trajectory intended to put it into an elliptical orbit around Earth with a perigee (closest point to Earth) of around 200 km. At this point, operations switched from launch to initial mission activities.

*A rear-facing camera on the Orion capsule capture another view of the ESM fairings being separated (centre bottom and (just visible) centre top). Credit: NASA*

The latter comprised two major elements: inside the Orion capsule, Christina Koch and Jeremy Hansen left their seats to set-up critical equipment and services. These included unstowing the fire-fighting equipment and mounting it on its assigned racks and then doing the same with the drinking water dispenser, toilet (which had its first malfunction, requiring Koch and Hansen to carry out a fix (the Toilet would again have issues on Flight Day 4, with the crew reporting it was depositing unpleasant odours in the main capsule) and other crew-related equipment. At the same time, Wiseman and Glover remained in their seats and ran through the protocols and check sheets for deploying the ESM’s solar arrays – vital for supplying Integrity with electrical power.

The solar arrays were deployed some 25 minutes after launch, and powered-up to start producing electrical power. At 50 minutes after lift-off, Hansen and Koch were back in their seats, the solar arrays were producing power and the go was given for two orbit-changing manoeuvres.

*One of Integrity’s four deployed solar arrays with Earth as a backdrop, as seen from a camera mounted on one of the other solar arrays. Credit: NASA*

The first was a short burst of the ICPS RL-10 engine, raising the perigee of Integrity’s orbit whilst maintaining its elliptical form. This was followed by a second 15-minute burn of the RL-10, extending Integrity’s perigee and apogee (the latter to some 70,000 km from Earth, placing the vehicle in a high Earth orbit.

This second RL-10 burn expended almost all remaining fuel in the ICPS, accelerating Integrity almost to the velocity required to complete a trans-lunar injection (TLI) manoeuvre. However, this is not what happened. Instead, with the ICPS separated and orbiting Earth independently of Integrity, Glover and Wiseman commenced what NASA normally refers to as an RPOD simulation, but which for Artemis 2 was simply called “proximity operations”.

RPOD Simulations / Proximity Operations

RPOD – Rendezvous, Proximity Operations and Docking – is a core part of modern day space operations with NASA, being fundamental to crews and supplies being able to launch to and reach the International Space Station (ISS) and then dock safety with it either under automated or manual control.

For the Artemis programme, being able to carry out a successful RPOD is vital to all the lunar surface missions, as they must be able to rendezvous and temporarily dock with the Moon- orbiting Human Landing System (HLS) vehicle which will actually deliver nominated crew members to the surface of the Moon, and then re-dock with the HLS vehicle to allow the surface mission crew return to their Orion craft for a return to Earth.

A conceptual rendering of Integrity performing a simulated RPOD with its ICPS as part of the proximity operations. Thee “docking target” can be seen within the open end of the ESM adaptor fairing. Credit: ESA

To this end, the ICPS had been equipped with a rendezvous and docking target, allowing Wiseman and Glover to test out the docking heads-up display whilst also using Integrity’s RCS thrusters to make simulated rendezvous approaches to the ICPS, aborting before the two vehicles actually made contact. In addition, Wiseman and Glover used manual control of the Orion to test proximity manoeuvring and close formation flying around the ICPS – both the POD and proximity operations marking the first time Orion had ever been manually flown. Both astronauts praised the vehicle’s handling qualities prior to returning the craft to its autopilot.

With Integrity well clear of the ICPS, the latter deployed two CubeSats then fired its RL-10 for a final time, placing it on a destructive re-entry into the upper atmosphere. At this point the crew moved to the next phases of initial operations.

Initial Mission Highlights

First, the Orion’s “gymnasium” – a flywheel device capable of allowing multiple exercises – was set-up and crew members took it in turns exercising, putting Integrity’s life support system through something of a stress test. After this, the crew set-up the food reheater and had dinner together from their rather impressive menu of meal choices. A 4-hour sleep period was then taken, allowing the crew some much needed rest.

Artemis 2 is providing unprecedented coverage, with 2/7 livestreams from the vehicle, frequent mission updates and interviews with the crew – such as this one from Saturday, April 4th, 2026. Form l to r: Reid Wiseman, Jeremy Hansen, Christina Koch and Victor Glover. Credit: NASA / AP

The sleep period was short as a further orbital manoeuvre was required to again raise Integrity’s perigee away from Earth and place it on a trajectory suitable for a TLI burn. With this complete, the crew settled back for another 4-hour sleep period whilst NASA mission control reviewed the overall performance of Orion and its systems to determine if Integrity was good to go for a free-return flight for the Moon.

Authorisation was given for TLI on flight day 2 after the crew had risen and eaten. The manoeuvre comprised a burn of the ESM’s AJ10 main engine of just under 6 minutes, using some 450 kg of hypergolic propellants. It pushed Integrity out of Earth’s orbit and on its way to pass around the Moon. This free return trajectory meant the vehicle would not need to use its AJ10 engine as it passed around the Moon in order to head back to Earth – gravity would do the work for the mission. However, the ESM’s propulsion systems would be required for various mid-course correction manoeuvres.

The first of these course corrections was due on Flight Day 3. However, such was the accuracy of the SLS’s performance coupled with that of Integrity itself, this manoeuvre was discarded – the vehicle was precisely on the course it needed. On Flight Day 4 Hansen (a Canadian fighter pilot) and Koch (a jet-qualified civilian pilot) took the controls of Orion and put the vehicle through a further series of RCS tests, evaluating its ability to complete both 3- and 6-degrees of freedom of movement manoeuvres (that is, rolling, pitching and yawing around various axes without altering its general trajectory). Both Koch and Hansen reported the vehicle presented excellent and stable handling.

Currently, the crew is due to pass around the Moon on Monday, April 6th. 2026 as they do so, they will reach a distance of approximately 406,773 kilometres from Earth, beating the previous record for the furthest humans have travelled from Earth to date – set by the abortive Apollo 13 mission in 1970 – by some 6,000 km. At this point, Integrity will be some 7,600 km beyond the surface of the Moon’s far side as it starts its journey home. The closest Artemis 2 will come to the surface of the Moon is approximately 6,513 km.

During the intervening period, the crew continue to test Integrity’s systems and capabilities and carry out a range of experiments, notably related to crew health and welfare. As a part of this work, Integrity carries two key experiments: AVATAR – A Virtual Astronaut Tissue Analogue Response, and an experiment system called ARCHeR (Artemis Research for Crew Health & Readiness (if there is one thing you definitely can say about NASA is that they work very hard at their acronyms!)

AVATAR can mimic individual astronaut organs, allowing medical experts evaluate tissue and other responses to various aspects of spaceflight and monitor essential biomarkers. AVATAR has been flown aboard the ISS several times, but this mission marks its first deep space mission – one that carries it and the Artemis 2 crew through the Van Allen radiation belts – thus offering the opportunity to gain further insight into the potential impact of these highly radioactive zones as Integrity zooms through them at several thousand km/h.

ARCHeR (which I cannot help think was named by an NASA fan of Star Trek (see Jonathan Archer (Scott Bakula), first commander of the Star Ship Enterprise, NX01) uses movement and sleep monitors worn by the crew to gather real-time health and behavioural information for crew members so scientists can study sleep patterns and overall health performance.

Further, Artemis 2 is testing and demonstrating the Orion Artemis II Optical Communications System (O2O). This is an optical communications system uses laser beams for two-way communications between Earth and the mission. Smaller and lighter than a conventional radio system, O2O also uses less power and increases transmission rates (up to 200 Mbits per second). If successful, O2O could become a feature of future Artemis missions from Artemis 4 onwards and used in potential human missions to Mars.

I’ll have more on Artemis 2 next week. In the meantime, you can follow the mission in real-time, via NASA’s 24/7 livestream.

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