In June a four-person crew will enter a hangar at NASA’s Johnson Space Center in Houston, Texas, and spend one year inside a 3D printed building. Made of a slurry that—before it dried—looked like neatly laid lines of soft-serve ice cream, Mars Dune Alpha has crew quarters, shared living space, and dedicated areas for administering medical care and growing food. The 1,700-square-foot space, which is the color of Martian soil, was designed by architecture firm BIG-Bjarke Ingels Group and 3D printed by Icon Technology.
Experiments inside the structure will focus on the physical and behavioral health challenges people will encounter during long-term residencies in space. But it’s also the first structure built for a NASA mission by the Moon to Mars Planetary Autonomous Construction Technology (MMPACT) team, which is preparing now for the first construction projects on a planetary body beyond Earth.
When humanity returns to the moon as part of NASA’s Artemis program, astronauts will first live in places like an orbiting space station, on a lunar lander, or in inflatable surface habitats. But the MMPACT team is preparing for the construction of sustainable, long-lasting structures. To avoid the high cost of shipping material from Earth, which would require massive rockets and fuel expenditures, that means using the regolith that’s already there, turning it into a paste that can be 3D printed into thin layers or different shapes.
The team’s first off-planet project is tentatively scheduled for late 2027. For that mission, a robotic arm with an excavator, which will be attached to the side of a lunar lander, will sort and stack regolith, says principal investigator Corky Clinton. Subsequent missions will focus on using semiautonomous excavators and other machines to build living quarters, roads, greenhouses, power plants, and blast shields that will surround rocket launch pads.
The first step toward 3D printing on the moon will involve using lasers or microwaves to melt regolith, says MMPACT team lead Jennifer Edmunson. Then it must cool to allow gasses to escape; failure to do so can leave the material riddled with holes like a sponge. The material can then be printed into desired shapes. How to assemble finished pieces is still being decided. To keep astronauts out of harm’s way, Edmunson says the goal is to make construction as autonomous as possible, but she adds, “I can’t rule out the use of humans to maintain and repair our full-scale equipment in the future.”
One of the challenges the team faces now is how to make the lunar regolith into a building material strong enough and durable enough to protect human life. For one thing, since future Artemis missions will be near the moon’s south pole, the regolith could contain ice. And for another, it’s not as if NASA has mounds of real moon dust and rocks to experiment with—just samples from the Apollo 16 mission.
So the MMPACT team has to make their own synthetic versions.
Edmunson keeps buckets in her office of about a dozen combinations of what NASA expects to find on the moon. The recipes include varying mixtures of basalt, calcium, iron, magnesium, and a mineral named anorthite that doesn’t occur naturally on Earth. Edmunson suspects that white and shiny synthetic anorthite being developed in collaboration with the Colorado School of Mining is representative of what NASA expects to find on the lunar crust.
Yet while the team feels that they can do a “reasonably good job” of matching the geochemical properties of the regolith, says Clinton, “it’s very hard to make the geotechnical properties, the shape of the different tiny pieces of aggregate, because they’re built up by collisions with meteorites and whatever has hit the moon over 4 billion years.”
There are other X factors to account for when building on the moon—and a lot can go wrong. Gravity is much weaker, there’s a chance of moonquakes that can create vibrations for up to 45 minutes, and temperatures at the south pole can get as high as 130 degrees Fahrenheit in sunlight and as low as –400 degrees at night. Abrasive moon dust can clog machinery joints and bring hardware to a screeching halt. During the Apollo missions, regolith damaged space suits, and inhaling dust caused astronauts to experience hay-fever-like symptoms.
Constructing Mars Dune Alpha, the test habitat in Texas, had an even bigger X factor: The human race has never brought a sample of Martian soil back to Earth, so Icon had to simulate the material, based on predictions of what it is made out of—such as that it’s rich in basalt. (They call their building material “lavacrete.”) The most important part to NASA officials, says CEO Jason Ballard, was getting the Martian soil’s color match right, to accurately mimic what it would be like to live on the Red Planet.
The structure took one month to 3D print, he says. Their process uses a giant printer arm with a nozzle that extrudes a steady supply of lavacrete. They start by outlining the footprint of the structure, adding layers and building upward like a coiled clay pot.
Mars Dune Alpha is also the first structure built by Icon with a 3D printed roof. The original design called for tilted semicircles, but the design had to be updated in order to meet the building code for the hangar in Houston. The current roof design rises up to meet in the middle of the structure like two waves meeting in the ocean. Icon printed the roof panels separately, then added them to the top of the structure.
“Building humanity’s first home on another planet will be one of the most ambitious construction projects in human history and will push technology, engineering, science, and architecture to new heights,” Ballard told WIRED by email.
Icon also has a $57.2 million NASA contract to research lunar construction research and development. As part of that effort, the company commissioned a study of what a moon base built in the next 10 years could look like. Designs commissioned by Icon and created by the Bjarke Ingels group envision a collection of torus, doughnut-shaped structures with hard outer shells that could protect a four-person crew from meteorites, moonquakes, radiation, and rapid temperature swings.
Experiments with melting regolith in vacuum chambers make up the bulk of Icon’s moon habitat construction research today. These chambers simulate the airless conditions on the moon and allow researchers to test thermal extremes. “We think we have the major mechanical systems worked out,” Ballard says, and now they are trying to strike a balance between the material’s strength and brittleness and achieve an appearance that he calls a “lunar ceramic.” The most important variables in that testing process are the power settings for the lasers, how long to allow cooling, and the geochemical makeup of the regolith, which may vary based on location. Different materials have different melting temperatures, he says, so “you can’t just show up and blast the laser at the same power no matter where you are, and you can’t cool it at the same rate.”
In 2024, the MMPACT team will also test their abilities to melt regolith in a vacuum chamber using lasers or microwaves. Right now they’re testing them separately. “The team has had ideas about using both technologies together—but that will take a bit more time (and funding) that we currently don’t have,” Edmunson wrote in an email.
They’ll also test their 3D printing, starting by making pieces of a landing pad within the vacuum chamber. This construction technology “will be the future of everything” built on the moon, Edmunson says, “but right now we’re focusing on the landing pads because that’s tops in terms of the safety of infrastructure on the lunar surface and how to protect it.” Building landing pads will be critical to keeping dust kicked up by spacecraft from harming important structures like radiation shields, garages, and roads, or from clouding landing conditions, Edmunson says. A rocket engine firing at the lunar surface without a landing pad could potentially send particles into orbit that could damage satellites or the Lunar Gateway orbiter, which NASA intends to build as a way station for visiting astronauts.
Roughly a year from now, the MMPACT team will run a dress rehearsal of a planned 2027 moon mission. Again using a vacuum chamber, they’ll put the robotic arm with an excavator scoop atop a bed of simulated regolith about the size of a kid’s sandbox. The goal will be to test its sorting and scooping capabilities in moonlike conditions; they’ll purposely let simulated rock get in the way of the scoop as it tries to collect the regolith. If a rock is too big, the excavator should work around it, but if it’s the size of the scoop or smaller, it should be sorted into piles of material—one pile fit for melting and another for waste.
Learning how to build on the moon may help enable the first human mission to Mars—but figuring out how to construct buildings under extreme conditions with locally available material could also pay off big on Earth. One way is by making advances in alternatives to concrete. Concrete is made with materials like limestone and sand, bound together with cement. Making cement is a pollution-prone process, accounting for 8 percent of the global carbon footprint. It’s also heavy, making it unsuitable for construction off Earth.
A Tennessee-based company called Branch Technology wants to start using proteins as an alternative to cement, to create a building material that weighs only about a tenth as much as concrete. Through a partnership with Stanford University and NASA’s Ames Research Center, they plan to build structures with lunar regolith that’s held together with bovine proteins that have been genetically engineered to bind lunar or Martian soils. They tested their material aboard the International Space Station last summer. “If this could become a concrete substitute, the applications are myriad and far less polluting than concrete processes that exist now,” former Branch CEO Platt Boyd said at the company’s lunar habitat demonstration last fall.
A cement-free approach may also offer solutions for people in places on Earth where concrete is imported for building projects. “Melting basalt on the moon and melting basalt on Hawaii—you know, it’s not too different,” Edmundson says.
And more broadly, the science of 3D printing space habitats may help make building housing on Earth cheaper and faster. This week, Icon is kicking off a competition with $1 million in prize money that challenges teams to design 3D printed houses that cost no more than $99,000. Designs must have at least one bedroom and one bathroom and meet residential code requirements, since winners could join the catalog of home layouts on offer from Icon.
Building in an environment where you minimize what you bring in and maximize using what’s available unlocks new innovation, says Branch Technology lunar construction program lead David Goodloe. “The lunar construction manufacturing ecosystem really is a greenhouse for new ideas and how we think about building in the most challenging environments humans have ever built in,” he says. “We’re going to come up with new ways to build that are better because of that requirement, and that’s going to translate to the construction industry at large.”
Update 5-23-2023 10:29 am ET: This story was updated to correct the name of Icon CEO Jason Ballard.