A small-scale replica of a lunar habitat is taking shape at Purdue University. The goal is to prepare for life in a hostile environment—including our own.
By guest author Lee Kamping-Carder from Wall Street Journal
The home is pelted with micrometeorites as fast as bullets and jostled by quakes that last for hours. Temperatures can climb past 250 degrees during the day and plunge below -200 degrees at night. Looking out the window risks radiation exposure. A plumbing leak could spell doom.
But if the Resilient Extra-Terrestrial Habitats Institute accomplishes its goals, the inhabitants will stay safe amid the hostile conditions. Funded with a USD 15 million grant from the National Aeronautics and Space Administration, the five-year research project combines advanced computer simulations and physical tests to glean insights into how to create a lunar habitat that will keep astronauts alive. The work will help inform how humans build a lasting presence on the moon.
This is no longer an academic question. NASA, with the help of international and commercial partners, plans to return people to the moon in 2024. In the following decade, the agency wants to establish “a sustained long-term presence on the lunar surface,” and build up infrastructure such as communications, power generation and waste disposal. Eventually, the so-called Artemis Base Camp could accommodate a crew of four astronauts with the goal of spending a month or two at a time on the surface.
It’s a lot closer than many people realize, says Ariel Ekblaw, founder and director of the Massachusetts Institute of Technology’s Space Exploration Initiative. She expects a structure to be built on the moon late this decade or in the early 2030s.
China has plans to start establishing an inhabited lunar station this decade. Jan Woerner, the European Space Agency’s director general, in 2016 kicked off Moon Village, an international, collaborative initiative for moon exploration. Roughly a dozen private lunar-transportation companies are readying robotic missions to the surface, according to Jessy Kate Schingler, co-founder and director of policy and governance at the Open Lunar Foundation, a San Francisco nonprofit advocating for peaceful and cooperative approaches to lunar settlement. There could be up to 1 billion metric tons of water in the form of ice on the moon, which could support hundreds of thousands of people working there, she says.
Still, a lunar habitat will need to withstand failures and repair itself when there are no humans on board. “It will have smarts,” says Julia Badger, autonomous systems technology discipline lead at NASA’s Johnson Space Center. “It will be able to handle a lot of the things it needs to do on its own.”
That’s where RETHi comes in. Dr. Badger, a research collaborator on the project, expects it to inform NASA’s moon missions and beyond. It could also help teach earthbound architects and engineers how to better build for a future of increasingly dense cities, limited resources and worsening climate change.
The project is led by Purdue University, in collaboration with Harvard University, the University of Connecticut and the University of Texas at San Antonio, with corporate partners Collins Aerospace and ILC Dover, a maker of engineered films and fabrics, including inflatable space habitats.
RETHi’s tests will examine what could happen under a range of disaster scenarios, from a micrometeorite punching a hole through a habitat to an hourslong moonquake jiggling the pipes of the environmental control and life support system. “You’re looking into the future to see what could happen, what’s most likely to happen, and then you’re trying to determine what’s the best way to deal with those likely scenarios,” says Shirley Dyke, a professor of mechanical and civil engineering at Purdue and RETHi’s executive director.
The moon offers no shortage of hardships. Lunar soil, known as regolith, is both sharp and fluffy, says Dr. Ekblaw. “It’s confectioners’ sugar that’s like glass,” says Dr. Dyke. It works its way into machinery, wears down equipment and accumulates on solar panels. There is no breathable air and only a sixth of Earth’s gravity. Extended stays pose a radiation risk. Nighttime lasts for roughly 14 days, interrupting solar-power generation.
For this reason, many plans for lunar habitats focus on the “peaks of eternal light,” a fanciful term for areas that receive near constant sunlight, on the Shackleton crater at the moon’s south pole. Scientists have also found water in the form of ice in the poles, suggesting it could be mined and turned into oxygen and hydrogen for breathable air and rocket fuel.
The RETHi project focuses on three areas: resilience, or building a habitat that can stand up to the hostilities of the surface; awareness, or being able to detect and diagnose problems through an array of sensors; and robotics, or developing machines that can autonomously fix problems. For Dr. Dyke, emergencies are inevitable.
Dozens of faculty members and students at the four universities have spent the past year designing computer models and sourcing materials for their experiments.
Last month, students and faculty at Purdue began real-world tests on a 4-foot-high, 8-foot-wide geodesic dome and other equipment in a lab on campus. They are simulating the effects of damage from a meteorite strike or other sources by hitting the dome with specialized hammers and by using an electrodynamic shaker. Other tests will involve a thermal blanket, which sucks up heat, to simulate temperature swings.
The team is also developing versatile robots that can handle different tasks and materials, including fabrics, and redesigning habitat components to make them easier for robots to work with. “If things go wrong with a habitat, robots will need to be sent out to deal with it—particularly during uncrewed periods, when astronauts won’t be around to be involved,” Harvard’s Justin Werfel, who leads the robotics team, writes in an email.
Renderings of the Purdue concept—less a blueprint and more a conceptual framework—show a cluster of dome-shaped buildings, mostly buried in regolith for insulation against radiation. Cupolas offer a place for astronauts to look at the Earth. Ladder rungs are spaced about a meter apart to accommodate the lack of gravity. There are plants and books. “When you’re not allowed to go outside freely, that’s a huge stress to anyone,” says Takaharu Igarashi, a master’s student in aerospace engineering at Purdue who designed the renderings.
Research efforts elsewhere are exploring approaches such as habitats in the shape of a donut-like torus or tapered cylinders. One of the more promising construction methods is 3-D printing with lunar soil, which would reduce the expense of launching materials from Earth. ICON, the Austin startup better known for 3-D printing homes on Earth, is running lab tests on simulated lunar soil to find ideal printing conditions.
The architecture firm Skidmore, Owings & Merrill collaborated with MIT faculty, as well as scientists and engineers at the European Space Agency, to design one potential habitat concept. The series of multistory structures would be made of a rigid frame surrounded by an inflatable shell and bolstered by walls of 3-D-printed regolith. Accommodating four people, the layout would maximize interior space, while the high ceilings take advantage of low gravity, and the stories allow for separating space into different uses.
Assuming astronauts might stay for months at a time, “you really do have to center your design approach on the well-being” of residents, says Colin Koop, a SOM design partner who leads the project with senior designer Daniel Inocente.
An ESA report studying the concept offered several potential solutions to challenges, including moving crew quarters to a lower level to protect against solar storms and radiation, but said that something resembling the structure “might well end up on the lunar surface in years to come.”
Another approach is a moving moon base, with crew traveling hundreds of kilometres over the surface in fuel-cell-powered, pressurized, mobile habitats, says Didier Schmitt, head of the strategy and coordination group at ESA’s directorate of human and robotic exploration. “If you have a moon base, it’s like if you have a house in the countryside. If you have no car and no mobility, you’re stuck,” he says.
Beyond the hostility of the lunar environment, myriad practical and policy challenges exist, including the still exorbitant cost of space launches and the question of sharing territory and resources between international and private players. “The questions we face of managing resources, communication standards, infrastructure, benefit sharing, taxation—in some sense they’re the most base questions of human societies,” Ms. Schingler says.
Much of the research into lunar habitats will have applications closer to home. A lunar structure could help engineers on earth design for a future of extreme weather events, where homes face multiple environmental hazards, says Herta Montoya, a RETHi participant and civil engineering Ph.D. student at Purdue, pointing to the recent wildfires in California that followed droughts and earthquakes.
“The things that we’re going to be learning in this project should have a huge impact on how we could approach resilience of our homes here on Earth,” Dr. Dyke says.