In humanity’s quest to explore Mars, getting there is only half of the battle. To keep astronauts safe while they explore the planet, we’ll need sophisticated habitats, life support systems, and communications. We’ll also need a new type of spacesuit.
To understand the challenges of building a suit that can withstand the Martian environment and to learn what steps engineers are already taking to address these challenges, we spoke to two NASA engineers about what it takes to make such a spacesuit.
Designing a spacesuit is no easy feat, explained Kristine Davis, a spacesuit engineer at NASA’s Johnson Space Center who works on the pressure garment systems team for NASA’s latest spacesuit design, the xEMU or Exploration Extravehicular Mobility Unit.
A modern spacesuit consists of a number of components: There is the pressure garment system or PGS, the part a person actually wears including the helmet, and then the portable life support system, which is the backpack of the suit and provides breathable air and other essentials for performing spacewalks. There’s also a team that works on parts like lights and cameras and other auxiliary systems for the suit.
Of course, astronauts come in varying shapes and sizes, so a suit can’t be one-size-fits-all. “Our suits are modular, so we can mix and match components. So we have small, medium, and large parts that we can put together to fit a person,” Davis said. “We can fit a really large range of people. With the xEMU we really put a focus on fitting the smaller range of our crew sizes, so we can deliver a suit that fits the smaller range of the population, both male and female.”
One reason for the focus on smaller sizes is the increasing number of female astronauts working on NASA projects. The suits aren’t actually separated by gender, however. “Our suits aren’t gendered, so we have one suit for both males and females,” David said. “Because the suits aren’t conformal, they don’t need to be changed for body shapes in the way that clothing is.” Instead, suits are fitted to an anthropometric range, which refers to measurements such as arm length or chest diameter.
Mars is an inhospitable planet (though some scientists hope to change that), with temperatures on the surface ranging anywhere from minus 140 degrees Celcius (minus 284 Fahrenheit) to 30 degrees C (86 degrees F) — and dust storms, radiation, and a thin, carbon dioxide-rich atmosphere to contend with. All of that makes spacesuits a protective necessity and requires them to be tough enough to withstand all of those factors while still allowing their wearers to move around, using their fingers and hands, and walk comfortably.
Compared to designing for the moon, “We have more of a radiation environment on the Martian surface, not only higher energy radiation but also ultraviolet radiation,” Davis said. “For long-duration missions, we need to make sure that the materials can stand up to that environment.”
There are also challenges with the atmosphere. Mars once had a thick atmosphere; it’s thin today, but still thicker than the absence of atmosphere on the moon or in space. So systems like the portable life support backpack can work on both the moon and the International Space Station (ISS), but will need to be changed for Mars.
In addition, there’s the problem of dust, which wreaks havoc on electronics and rovers during lunar missions by sticking to everything and causing degradation. The dust on the moon “is like tiny shards of glass,” Davis said, due to the fact there is no atmosphere and no wind on the moon, so there is no friction to wear down the dust’s sharp edges. That means it has to be kept out of bearings and components as it can eat through spacesuit fabric.
On Mars, “dust is still an issue,” Davis says. “But it’s a different kind of an issue. You have more erosion from the wind and storms, so the dust isn’t quite as sharp as on the moon. But it is dangerous in its own way. The dust has perchlorates in it, and because of the high carbon dioxide atmosphere on Mars, those are very dangerous if you inhale them and can cause cancer. Our dust control will have to be stepped up so the crew members won’t inhale any dust particles.”
One challenge which makes designing for Mars different from designing for the ISS, for example, is the gravity involved. The ISS is a microgravity environment and therefore requires little use of the legs as the astronauts propel themselves around using their hands and arms. “The only thing we really use the feet and legs for in the ISS environment is for foot restraints at worksites to lock you in place,” Davis explains. “It’s very different when we’re looking at a partial gravity environment like the moon and one day Mars.”
On a partial gravity environment like Mars, the spacesuit engineers need to strike a balance between a suit that protects the astronauts and fulfills all the functions it needs to, and one which is not too heavy and cumbersome to wear. Mars has a gravity just over a third of Earth’s, while the moon’s gravity is around one-sixth. That means the suits feel heavier on Mars than they would in other environments — and the human body will change.
Current complete spacesuits including life support systems weigh around 300 pounds, and although the next-generation suits are still having their weight finalized, they’ll probably be similar. On the moon, that means carrying the equivalent of around 50 pounds, but on Mars, it’ll be around 100 pounds.
“Although it doesn’t quite feel like 100 pounds when you’re walking around, as the suit will hold some its own weight when pressurized, especially when you’re standing upright,” Davis said. “The legs almost act like springs, so you don’t feel the full weight when you’re moving around.”
The engineers also find ways to help the astronauts bear the weight, such as using waist straps similar to those found on hiking backpacks, that distribute weight around the hips and shoulders.
To test how a suit would feel in the lighter gravity of space environments, NASA uses a system called the Active Response Gravity Offload System, or ARGOS. This consists of a harness that is hooked up to a test subject in a spacesuit, and a series of pulleys that can have weights attached to offload the subject’s mass. The result is a system that can re-create the gravity environments of the moon or Mars, letting test subjects jump high in the air like they could on the moon, or experience the microgravity of the ISS and learn to move around using their hands.
“We have big buckets of sand that they get in and out of,” Davis explained. “And treadmills that can do different degrees of tilting. So we simulate what it’s like to do a spacewalk similar to what they’d have to do on the lunar surface. They take samples and use the tools that we develop. It’s not perfect — the tools that they use aren’t offloaded, and the system itself does give a little bit of bias — but it gives us a better idea of what the suit would look like in practice.”
They have ways to test out materials for space environments as well, performing what are called “ground tests,” in which the target environment is recreated as faithfully as possible here on Earth. For testing gear for Mars, that involves building a chamber in which the pressure, UV radiation, and atmosphere of the planet can be simulated, along with variations in temperature and potentially recreating the massive dust storms that the planet experiences as well.
The trouble with trying to re-create Martian dust, however, is that we don’t know exactly what it’s composed of and how it differs across the planet. Luther Beegle, a NASA scientist who has worked on creating “Mars simulant,” as the faux-Martian dust is known, describes the problem: “It simulates one portion of the material we find on the surface of Mars. There’s always something that you don’t know is there. We don’t know exactly 100% what all the chemical reactions of these dust particles are.”
The dust on Mars isn’t uniform across the entire planet either, which adds a further issue. “We made a simulant which recreates the bulk chemical and physical properties of wind-blown dust,” Beegle said. “It simulated around 80 to 85% of what that material was. But depending on where you are on Mars, different regions have different localized mineralogy.”
So although on-ground tests are an invaluable way to test new hardware like spacesuits, to be entirely confident that materials can withstand harsh space missions, you need to test them in the real environments where they will be used.
To test out spacesuit materials on Mars, NASA scientists have come up with an ingenious plan. The Perseverance rover, which will explore the planet and is being launched this summer, will carry a variety of scientific instruments, including a spectrometry instrument called SHERLOC (the Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals). And that instrument requires a set of calibration targets of known materials.
But instead of sending the usual calibration materials of pure minerals, like those used on Curiosity’s SuperCam instrument, SHERLOC’s scientists have teamed up with the spacesuit designers to use spacesuit materials for calibration. That way, the materials can be tested in situ on Mars without adding any extra unnecessary weight or space to the already-packed rover.
Beegle is the principal investigator for SHERLOC as well, and he described how the experiment came about: “We got creative. And we found fabric we can do both imaging and elemental targeting with. It really added a second layer to what we’re doing. We got Johnson [Space Center, where spacesuits are designed] involved too, and we like to be one big NASA family. The more we thought about it, the more excited we got.”
SHERLOC will perform its calibrations using a board containing five different samples of materials in 2cm × 2cm squares: Polycarbonate which is used in face shields, plus Vectran, Ortho-Fabric, Teflon, and a coated Teflon, which are used in the spacesuits.
“About every three to six months, we’re going to re-calibrate the instrument, which means we’ll be able to look at our samples again,” Beegle explained. “What we’re looking for is degradation. We’re going to check that the fabric itself stays intact using visible imaging and spectra.” For example, one of the fabrics is woven, and if its weave begins to break down, that would be visible to SHERLOC’s instruments. “We could detect that with microscopic imaging. We could see whether the weaves were modified or degrading.”
Hopefully, all of the samples stand up to the environment and don’t degrade at all over the two to six-year experiment. But if degradation does occur, the spacesuit team can perform more ground tests to identify the cause, to ensure that spacesuits will continue to function in the Martian environment in the long term.
As well as expanding the current xEMU design, Davis is also part of a team working on new technologies in early stages of development — looking at the sort of speculative ideas that could be used in future designs. One such concept she and others are working on is an Augmented Reality system where a display on a helmet could show information as astronauts work.
“We’re hoping that one day we can have some kind of display that the crew members can use, especially for working through procedures,” she explained. “It could display things like procedures, or camera views. And maybe cautions or warning systems, or your EVA time, your oxygen levels, all the information that would be useful to have handy.”
The team has considered different technologies to achieve this effect and is starting work on a prototype using a projection system. This would be particularly valuable on Mars, where there is a communication delay of at least seven minutes in each direction between there and Earth.
Currently, when astronauts are performing complex tasks on a location like the ISS, ground control walks them through each step via audio instructions. But the communication delay with Mars would make this time-consuming and inefficient. The idea is that an AR display on the helmets could show step-by-step instructions and allow the astronauts to work autonomously without having to wait for instructions from Earth.
Exactly how NASA’s current spacesuit design will evolve for future Mars missions depends first on how it works out on upcoming missions to the moon. NASA aims to send astronauts back to the the moon by 2024, and when they go, they’ll be wearing the xEMU suit that Davis helped design. And from there, it’s on to Mars.
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