The most interesting work, however, has to do with NASA’s next-generation spacesuit for astronauts going to the moon—the eXploration Extravehicular Mobility Unit, or xEMU. It is ostensibly the successor to the spacesuits worn by Neil Armstrong, Buzz Aldrin, and other Apollo astronauts when they set foot on the lunar surface half a century ago. But it also incorporates what we’ve learned through the EMUs used in orbit during the space shuttle and ISS eras of human exploration, as well as the hard lessons from Apollo. The goal behind Artemis is to have people living and working on the moon. New spacesuits will be critical to ensuring that the experience is safe and comfortable.
“We are so excited about putting people back on the moon,” says Richard Rhodes, a spacesuit engineer at NASA who’s working on the xEMU. “Our main goal is that the crew doesn’t even think about us. They put the suit on, and they do their work—the science, the exploration—and do not even think twice about how mobile they are or how effectively they can work. That’s a tall order, but we’re trying to get as close to that as possible. We want to be invisible.”
Here are some of the biggest innovations we can expect out of xEMU.
“When you’re designing a spacesuit, you want it to move freely and efficiently, with the least amount of effort possible, so we can be as near to shirtsleeve mobility as possible,” says Rhodes. The goal is to limit the amount of volume in the suit, because the more volume there is, the harder astronauts must to work to bend their joints, and that can quickly grow exhausting.
The solution is to use bearings, since they rotate around a single point and ensure a constant amount of volume. The old Apollo suits used bearings only in the arms, because it was basically a multipurpose suit (used for both launch and entry, as well as lunar exploration). It needed to be light enough to accommodate all these different situations, and too many bearings could have weighed it down.
The xEMU has bearings that are lighter and hew closer to the joints than ones used for previous EMUs. The ones at the shoulders should allow astronauts to reach outward and lift objects more easily while reducing risk of injury to the upper body. There are finally bearings at the waist, hips, thighs, and ankles, creating much greater mobility in the lower body. “All of these together allow for very low-torque, low-energy mobility and motion,” says Rhodes.
The suits also have a variable pressure system to give astronauts more flexibility when they need it. It should allow them to get ready more quickly in the suit when it’s necessary, but also to lift materials or kneel down to study things when the situation calls for it.
The hip mobility bearings in particular are a big deal for moonwalking (no, not that kind of moonwalking). Apollo astronauts weren’t spending a whole lot of time on the surface of the moon during their missions, and the time they did spend was largely to just get to know this new environment. They quickly found it difficult to walk around normally in microgravity, and they were also very careful to avoid any dangers.
With such limited hip mobility, striding just wasn’t feasible. So they mostly shuffled; when they got more comfortable and more adventurous, they could manage a more loping gait to move faster. Trying to grab objects on the ground required an awkward lunge.
The xEMU is supposed to encourage normal walking as opposed to hopping, and make it easier to kneel down stably in one motion to work close to the ground—which wasn’t much of an option for Apollo astronauts. No more lunging for objects. This is going to make it much easier for astronauts to conduct worthwhile science on the ground, like examining geological samples or setting up complex instruments.
A huge lesson learned from Apollo was that lunar dust is terrible. The moon’s surface hasn’t been exposed to the kind of weathering Earth’s geology has faced. As a result, the lunar soil is very coarse and jagged, and it sticks to everything (yeah, I know I sound like Anakin Skywalker). It contaminates inner layers of the garment and any parts that are supposed to detach, and causes general wear and tear to the exterior of the suits.
So to avoid any exposed gaps, designers minimized components like zippers or wrist disconnects, as well as seams where dust could infiltrate. “We’re looking at more of a whole garment that goes over the entire assembly, with small features where you can still perform operational checks and disconnect things during a contingency,” says Rhodes. “It’s like a whole shirt and whole pants that’s all one piece, without breaks where dust can get inside.” And for areas where there are breaks (like bearings), the team is working on developing and incorporating seals that should keep dust out.
The xEMU helmets offer a wider range of vision than the Apollo helmets, with onboard lights to help illuminate dark places. They’ll have a HUD (heads-up display) for astronauts to access important information on the go. High-definition shoulder cameras will help record journeys as if right from the astronaut’s own eyes.
The “Snoopy caps” used for communications are a pretty recognizable part of EMUs, but as most astronauts who’ve been on spacewalks can attest, they can quickly get drenched in sweat, and their microphones don’t always work well after many hours of movement. The xEMU gets rid of the Snoopy cap for an audio system that’s embedded into the suit, voice activated to automatically pick up sounds as they’re spoken.
A common complaint among any astronaut who’s gone on an EVA is that the gloves are a menace. Their bulky layers mean you lose a lot of dexterity, and you also don’t necessarily know how much pressure you’re using when you grab something. Lack of circulation and the accumulation of moisture can lead to some nasty side effects, like brittle fingernails and even fungus. “Gloves are not a new challenge,” says Rhodes. “There’s absolutely room for improvement.”
The main improvements Rhodes and his team are working on for the xEMU is to make sure astronauts’ hands are protected from extreme temperature changes and dust, and that they can handle lunar material safely. NASA is also figuring out how to make it easier for them to do simple tasks like grasp tools and operate small equipment.
Back in 2014, Italian astronaut Luca Parmitano was on a spacewalk when his suit began to leak water, flooding the helmet and nearly drowning him. Engineers later found that contamination had caused water from the cooling system to back up—trouble exacerbated by the fact that the water and cooling loops were in such close contact. So the xEMU now keeps those loops completely separate to avoid another such emergency from happening.
The xEMU also sports a new carbon dioxide scrubbing system that uses two different absorption beds (in this case, small cans made of lithium hydroxide that readily attract and trap carbon dioxide). While one is being used, the other can be exposed to the vacuum of space and emptied out—so carbon dioxide is constantly scrubbed without forcing astronauts to come back inside to clean the absorption beds. The oxygen tanks are higher-pressure systems that should deliver oxygen for longer periods of time than Apollo suits did. The only limitation now for how long someone can stay in the suit, theoretically, is battery power.
Meanwhile, the xEMU is retaining some life support and safety features that are tried and true. There’s protection from micrometeorites based on a similar design for the current orbital EMUs. There’s also thermal protection to withstand the sharp temperature changes (from -250 °F in the shade to 250 °F under the sun).
Customized and future-proofed
Back in March 2019, NASA canceled plans for the first all-woman spacewalk because there weren’t enough correctly sized spacesuits—only larger ones were available.
It was a tough lesson about the need to make sure that suits are designed properly to accommodate people of all sizes. The agency has decided that with the xEMU, they’re leaving nothing to chance. Each suit will be custom fitted to the height, size, and comfort of the individual astronaut and will aim to provide the broadest range of motion for activities on the moon. If a moonwalk is canceled this time, it won’t be because the suits don’t fit.Spacesuit design is still a work in progress, though. “There’s not a lot of data on operation on the lunar surface,” says Rhodes. Any kind of feedback will be fantastic.” NASA intends to incorporate what it learns from the first few Artemis missions to improve the xEMU over and over again—with an eye toward making something that will work on Mars one day.