![\"\"](\"https:\/\/cdn.arstechnica.net\/wp-content\/uploads\/2026\/01\/50533753896_62b8791a3c_k.jpg\")
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NASA astronaut Kate Rubins inside the International Space Station in 2020.<\/p>\n
Credit:
\n NASA<\/p>\n<\/figure>\n
Rubins is now a professor of computational and systems biology at the University of Pittsburgh School of Medicine. She said treks on the Moon will be \u201ceven more challenging\u201d than her spacewalks outside the ISS.<\/p>\n
The Axiom spacesuit design builds on NASA\u2019s own work developing a prototype suit to replace the agency\u2019s decades-old Extravehicular Mobility Units (EMUs) used for spacewalks at the International Space Station (ISS). The new suits allow for greater mobility, with more flexible joints to help astronauts use their legs, crouch, and bend down\u2014things they don\u2019t have to do when floating outside the ISS.<\/p>\n
Astronauts on the Moon also must contend with gravity. Including a life-support backpack, the commercial suit weighs more than 300 pounds in Earth\u2019s gravity, but Axiom considers the exact number proprietary. The Axiom suit is considerably heavier than the 185-pound spacesuit the Apollo astronauts wore on the Moon. NASA\u2019s earlier prototype exploration spacesuit was estimated to weigh more than 400 pounds, according to a 2021 report by NASA\u2019s inspector general.<\/p>\n
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\u201cWe\u2019ve definitely seen trauma from the suits, from the actual EVA suit accommodation,\u201d said Mike Barratt, a NASA astronaut and medical doctor. \u201cThat\u2019s everything from skin abrasions to joint pain to\u2014no kidding\u2014orthopedic trauma. You can potentially get a fracture of sorts. EVAs on the lunar surface with a heavily loaded suit and heavy loads that you\u2019re either carrying or tools that you\u2019re reacting against, that\u2019s an issue.\u201d<\/p>\n
On paper, the Axiom suits for NASA\u2019s Artemis missions are more capable than the Apollo suits. They can support longer spacewalks and provide greater redundancy, and they\u2019re made of modern materials to enhance flexibility and crew comfort. But the new suits are heavier, and for astronauts used to spacewalks outside the ISS, walks on the Moon will be a slog, Rubins said.<\/p>\n
\u201cI think the suits are better than Apollo, but I don\u2019t think they are great right now,\u201d Rubins said. \u201cThey still have a lot of flexibility issues. Bending down to pick up rocks is hard. The center of gravity is an issue. People are going to be falling over. I think when we say these suits aren\u2019t bad, it\u2019s because the suits have been so horrible that when we get something slightly less than horrible, we get all excited and we celebrate.\u201d<\/p>\n
The heavier lunar suits developed for Artemis missions run counter to advice from former astronaut Harrison \u201cJack\u201d Schmitt, who spent 22 hours walking on the Moon during NASA\u2019s Apollo 17 mission in 1972.<\/p>\n
\u201cI\u2019d have that go about four times the mobility, at least four times the mobility, and half the weight,\u201d Schmitt said in a NASA oral history interview in 2000. \u201cNow, one way you can\u2026 reduce the weight is carry less consumables and learn to use consumables that you have in some other vehicle, like a lunar rover. Any time you\u2019re on the rover, you hook into those consumables and live off of those, and then when you get off, you live off of what\u2019s in your backpack. We, of course, just had the consumables in our backpack.\u201d<\/p>\n
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NASA won\u2019t have a rover on the first Artemis landing mission. That will come on a later flight. A fully pressurized vehicle for astronauts to drive across the Moon may be ready sometime in the 2030s. Until then, Moonwalkers will have to tough it out.<\/p>\n
\u201cI do crossfit. I do triathlons. I do marathons. I get out of a session in the pool in the NBL (Neutral Buoyancy Laboratory) doing the lunar suit underwater, and I just want to go home and take a nap,\u201d Rubins told the panel. \u201cI am absolutely spent. You\u2019re bruised. This is an extreme physical event in a way that the space station is not.\u201d<\/p>\n NASA astronaut Mike Barratt inside the International Space Station in 2024.<\/p>\n Credit: Barratt met with the same National Academies panel this week and presented a few hours before Rubins. The committee was chartered to examine how human explorers can enable scientific discovery at sites across the lunar surface. Barratt had a more favorable take on the spacesuit situation.<\/p>\n \u201cThis is not a commercial for Axiom. I don\u2019t promote anyone, but their suit is getting there,\u201d Barratt said. \u201cWe\u2019ve got 700 hours of pressurized experience in it right now. We do a lot of tests in the NBL, and there are techniques and body conditioning that you do to help you get ready for doing things like this. Bending down in the suit is really not too bad at all.\u201d<\/p>\n Rubins and Barratt did not discuss the schedule for when Axiom\u2019s lunar spacesuit will be ready to fly to the Moon, but the conversation illuminated the innumerable struggles of spacewalking, Moonwalking, and the training astronauts undergo to prepare for extravehicular outings.<\/p>\n I spoke directly with Rubins after her discussion with the National Academies. Her last assignment at NASA was as chief of the EVA and robotics branch in the astronaut office, where she assisted in the development of the new lunar spacesuits. I asked about her experiences testing the lunar suit and her thoughts on how astronauts should prepare for Moonwalks.<\/p>\n ,<\/p>\n \u201cThe suits that we have are definitely much better than Apollo,\u201d Rubins said in the interview. \u201cThey were just big bags of air. The joints aren\u2019t in there, so it was harder to move. What they did have going for them was that they were much, much lighter than our current spacesuits. We have added a lot of the joints back, and that does get some mobility for us. But at the end of the day, the suits are still quite heavy.\u201d<\/p>\n You can divide the weight of the suit by six to get an idea of how it might feel to carry it around on the lunar surface. While it won\u2019t feel like 300 pounds, astronauts will still have to account for their mass and momentum.<\/p>\n Rubins explained:<\/p>\n Instead of kind of floating in microgravity and moving your mass around with your hands and your arms, now we\u2019re ambulating. We\u2019re walking with our legs. You\u2019re going to have more strain on your knees and your hips. Your hamstrings, your calves, and your glutes are going to come more into play.<\/p>\n I think, overall, it may be a better fit for humans physically because if you ask somebody to do a task, I\u2019m going to be much better at a task if I can use my legs and I\u2019m ambulating. Then I have to pull myself along with my arms\u2026 We\u2019re not really built to do that, but we are built to run and to go long distances. Our legs are just such a powerful force.<\/p>\n So I think there are a lot of things lining up that are going to make the physiology easier. Then there are things that are going to be different because we\u2019re now in a partial gravity environment. We\u2019re going to be bending, we\u2019re going to be twisting, we\u2019re going to be doing different things.<\/p>\n It\u2019s an incredibly hard engineering challenge. You have to keep a human alive in absolute vacuum, warm at temperatures that you know in the polar regions could go as far down as 40 Kelvin (minus 388\u00b0 Fahrenheit). We haven\u2019t sent humans anywhere that cold before. They are also going to be very hot. They\u2019re going to be baking in the sunshine. You\u2019ve got radiation. If you put all that together, that\u2019s a huge amount of suit material just to keep the human physiology and the human body intact.<\/p>\n Then our challenge is \u2018how do you make that mobile?\u2019 It\u2019s very difficult to bend down and pick up a rock. You have to manage that center of gravity because you\u2019re wearing that big life support system on your back, a big pack that has a lot of mass in it, so that brings your center of gravity higher than you\u2019re used to on Earth and a little bit farther backward.<\/p>\n When you move around, it\u2019s like wearing a really, really heavy backpack that has mass but no weight, so it\u2019s going to kind of tip you back. You can do some things with putting weights on the front of the suit to try to move that center of gravity forward, but it\u2019s still higher, and it\u2019s not exactly at your center of mass that you\u2019re used to on the Earth. On the Earth, we have a center of our mass related to gravity, and nobody ever thinks about it, and you don\u2019t think about it until it moves somewhere else, and then it makes all of your natural motion seem very difficult.<\/p>\n Those are some of the challenges that we\u2019re facing engineering-wise. I think the new suits, they\u2019ve gone a long way toward addressing these, but it\u2019s still a hard engineering challenge. And I\u2019m not talking about any specific suit. I can\u2019t talk about the details of the provider\u2019s suits. This is the NASA xEMU and all the lunar suits I have tested over the years. That includes the Mark III suit, the Axiom suit. They have similar issues. So this isn\u2019t really anything about a specific vendor. These are just the difficulties of designing a spacesuit for the lunar environment.<\/p>\n<\/blockquote>\n NASA trains astronauts for spacewalks in the Neutral Buoyancy Laboratory, an enormous pool in Houston used for simulating weightlessness. They also use a gravity-offloading device to rehearse the basics of spacewalking. The optimal test environment, short of the space environment itself, will be aboard parabolic flights, where suit developers and astronauts can get the best feel for the suit\u2019s momentum, according to Rubins.<\/p>\n ,<\/p>\n Axiom and NASA are well along assessing the new lunar spacesuit\u2019s performance underwater, but they haven\u2019t put it through reduced-gravity flight testing. \u201cUntil you get to the actual parabolic flight, that\u2019s when you can really test the ability to manage this momentum,\u201d Rubins said.<\/p>\n NASA astronauts Loral O\u2019Hara and Stan Love test Axiom\u2019s lunar spacesuit inside NASA\u2019s Neutral Buoyancy Laboratory in Houston on September 24, 2025.<\/p>\n Credit: Recovering from a fall on the lunar surface comes with its own perils.<\/p>\n \u201cYou\u2019re face down on the lunar surface, and you have to do the most massive, powerful push up to launch you and the entire mass of the suit up off the surface, high enough so you can then flip your legs under you and catch the ground,\u201d Rubins said. \u201cYou basically have to kind of do a jumping pushup\u2026 This is a risky maneuver we test a whole bunch in training. It\u2019s really non-trivial.\u201d<\/p>\n The lunar suits are sleeker than the suits NASA uses on the ISS, but they are still bulky. \u201cIf you\u2019re trying to kneel, if you\u2019re thinking about bending forward at your waist, all that material in your waist has nowhere to go, so it just compresses and compresses,\u201d Rubins said. \u201cThat\u2019s why I say it\u2019s harder to kneel. It\u2019s harder to bend forward because you\u2019re having to compress the suit in those areas.<\/p>\n \u201cWe\u2019ve done these amazing things with joint mobility,\u201d Rubins said. \u201cThe mobility around the joints is amazing\u2026 but now we\u2019re dealing with this compression issue. And there\u2019s not an obvious engineering fix to that.\u201d<\/p>\n The fix to this problem might come in the form of tools instead of changes to the spacesuit itself. Rubins said astronauts could use a staff, or something like a hiking pole, to brace themselves when they need to kneel or bend down. \u201cThat way I\u2019m not trying to compress the suit and deal with my balance at the same time.\u201d<\/p>\n ,<\/p>\n The Moonwalker suit can comfortably accommodate a wider range of astronauts than NASA\u2019s existing EMUs on the space station. The old EMUs can be resized to medium, large, and extra-large, but that leaves gaps and makes the experience uncomfortable for a smaller astronaut. This discomfort is especially noticeable while practicing for spacewalks underwater, where the tug of gravity is still present, Rubins said.<\/p>\n \u201cAs a female, I never really had an EMU that fit me,\u201d Rubins said. \u201cIt was always giant. When I\u2019m translating around or doing something, I\u2019m physically falling and slamming myself, my chest or my back, into one side of the suit or the other underwater, whereas with the lunar suit, I\u2019ve got a suit that fits me right. That\u2019s going to lead to less bruising. Just having a suit that fits you is much better.\u201d<\/p>\n Mission planners should also emphasize physical conditioning for astronauts assigned to lunar landing missions. That includes preflight weight and endurance training, plus guidance on what to eat in space to maximize energy levels before astronauts head outside for a stroll.<\/p>\n \u201cThat human has to go up really maximally conditioned,\u201d Rubins said.<\/p>\n Rubins and Barratt agreed that NASA and its spacesuit provider should be ready to rapidly respond to feedback from future Moonwalkers. Engineers modified and upgraded the Apollo spacesuits in a matter of months, iterating the design between each mission.<\/p>\n \u201cOur general design is on a good path,\u201d Rubins said. \u201cWe need to make sure that we continue to push for increasing improvements in human performance, and some of that ties back to the budget. Our first suit design is not where we\u2019re going to be done if we want to do a really sustained lunar program. We have to continue to improve, and I think it\u2019s important to recognize that we\u2019re going to learn so many lessons during Artemis III.\u201d<\/p>\n ,<\/p>\n Barratt has a unique perspective on spacesuit design. He has performed spacewalks at the ISS in NASA\u2019s spacesuit and the Russian Orlan spacesuit. Barratt said the US suit is easier to work in than the Orlan, but the Russian suit is \u201cincredibly reliable\u201d and \u201cincredibly serviceable.\u201d<\/p>\n \u201cIt had a couple of glitches, and literally, you unzip a curtain and it\u2019s like looking at my old Chevy Blazer,\u201d Barratt said. \u201cEverything is right there. It\u2019s mechanical, it\u2019s accessible with standard tools. We can fix it. We can do that really easily. We\u2019ve tried to incorporate those lessons learned into our next-generation EVA systems.\u201d<\/p>\n Contrast that with the NASA suits on the ISS, where one of Barratt\u2019s spacewalks in 2024 was cut short by a spacesuit water leak. \u201cWe recently had to return a suit from the space station,\u201d Barratt said. \u201cWe\u2019ve got another one that\u2019s sort of offline for a while; we\u2019re troubleshooting it. It\u2019s a really subtle problem that\u2019s extremely difficult to work on in places that are hard to access.\u201d<\/p>\n It\u2019s happened before. Apollo 17 astronaut Harrison \u201cJack\u201d Schmitt loses his balance on the Moon, then quickly recovers.<\/p>\n Credit: Harrison Schmitt, speaking with a NASA interviewer in 2000, said his productivity in the Apollo suit \u201ccouldn\u2019t have been much more than 10 percent of what you would do normally here on Earth.\u201d<\/p>\n \u201cYou take the human brain, the human eyes, and the human hands into space. That\u2019s the only justification you have for having human beings in space,\u201d Schmitt said. \u201cIt\u2019s a massive justification, but that\u2019s what you want to use, and all three have distinct benefits in productivity and in gathering new information and infusing data over any automated system. Unfortunately, we have discarded one of those, and that is the hands.\u201d<\/p>\n Schmitt singled out the gloves as the \u201cbiggest problem\u201d with the Apollo suits. \u201cThe gloves are balloons, and they\u2019re made to fit,\u201d he said. Picking something up with a firm grip requires squeezing against the pressure inside the suit. The gloves can also damage astronauts\u2019 fingernails.<\/p>\n ,<\/p>\n \u201cThat squeezing against that pressure causes these forearm muscles to fatigue very rapidly,\u201d Schmitt said. \u201cJust imagine squeezing a tennis ball continuously for eight hours or 10 hours, and that\u2019s what you\u2019re talking about.\u201d<\/p>\n Barratt recounted a conversation in which Schmitt, now 90, said he wouldn\u2019t have wanted to do another spacewalk after his three excursions with commander Gene Cernan on Apollo 17.<\/p>\n \u201cPhysically, and from a suit-maintenance standpoint, he thought that that was probably the limit, what they did,\u201d Barratt said. \u201cThey were embedded with dust. The visors were abraded. Every time they brushed the dust off the visors, they lost visibility.\u201d<\/p>\n Getting the Artemis spacesuit right is vital to the program\u2019s success. You don\u2019t want to travel all the way to the Moon and stop exploring because of sore fingers or an injured knee.<\/p>\n \u201cIf you look at what we\u2019re spending on suits versus what we\u2019re spending on the rocket, this is a pretty small amount,\u201d Rubins said. \u201cObviously, the rocket can kill you very quickly. That needs to be done right. But the continuous improvement in the suit will get us that much more efficiency. Saving 30 minutes or an hour on the Moon, that gives you that much more science.\u201d<\/p>\n \u201cOnce you have safely landed on the lunar surface, this is where you\u2019ve got to put your money,\u201d Barratt said.<\/p>\n","protected":false},"excerpt":{"rendered":" Crew members traveling to the lunar surface on NASA\u2019s Artemis missions should be gearing up for a grind. They will wear heavier spacesuits than those worn by the Apollo astronauts, and NASA will ask them to do more than the first Moonwalkers did more than 50 years ago. The Moonwalking experience will amount to an […]<\/p>\n","protected":false},"author":1,"featured_media":44074,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[304,376,291,1545,1770,9510,190,566],"class_list":["post-44071","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","tag-artemis","tag-axiom-space","tag-commercial-space","tag-human-spaceflight","tag-kate-rubins","tag-mike-barratt","tag-nasa","tag-spacesuits"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/44071"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=44071"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/44071\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media\/44074"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=44071"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=44071"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=44071"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"\"](\"https:\/\/cdn.arstechnica.net\/wp-content\/uploads\/2026\/01\/53611493272_d9569c5132_k.jpg\")
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\n NASA<\/p>\n<\/figure>\nThe one who should know<\/h2>\n
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\n NASA<\/p>\n<\/figure>\nA bruising exertion<\/h2>\n
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