A design challenge that's out of this world
How do you build cities or even a single house on Mars when you don’t have access to the construction materials we enjoy on Earth? That’s the dilemma NASA put to 18 international design teams in the 3-D Printed Habitat Challenge. Their task was to design a virtual model of 3-D printed houses, which would be built ready for the arrival of astronauts on the red planet.
The Habitat Challenge - which has been running since 2015 - has three phases, each with multiple levels. Phase One was the design competition. Phase two focused on material technologies, requiring teams to create structural components. They’ve both been completed. The competition’s now in its third, final and most difficult phase. Teams are challenged to fabricate sub-scale habitats. There are five levels of competition – three construction levels and two virtual levels. For the virtual levels, teams must use Building Information Modelling software to design a habitat that combines allowances for both the structure and systems it must contain. The construction levels challenge the teams to autonomously 3D-print elements of the habitat, culminating with a one-third-scale printed habitat for the final level. There’s a total prize pool of $3 million on offer.
NASA’s Centennial Challenges Project manager, Monsi Roman, believes 3-D printed houses could be on other planets by late 2030, with the first probably on the moon. “That’s not far away,” Roman said. “And we need to send equipment and stuff up there way before that.”
Obviously problems other than housing need to also be solved for these micro villages. Visitors to Mars will need a power source, such as solar panels. They’ll need fuel for the return flight, and they’ll need roads so materials can be moved around safely.
Mars will be a challenging construction site. It’s dusty, cold and corrosive. And what if spare parts or extra materials are needed? A quick trip to Mitre 10 or Bunnings is out of the question. It’s not even like popping back from the moon - Mars is months away.
Monsi Roman says NASA’s thrilled with the ideas competing teams have come up with so far. “They are not just designing structures, they are designing habitats that will allow our space explorers to live and work on other planets. We are excited to see their designs come to life as the competition moves forward.”
NASA says it hopes that some of the technology and ideas developed through this competition can be used to produce affordable housing on Earth.
More than 165 submissions were received for phase one of the competition. First place went to Team Space Exploration Architecture and Clouds Architecture Office for their design, Mars Ice House. It features a large inflatable torus, a shape similar to an inner tube, that is surrounded by a shell of water ice. The Mars Ice Home design has several advantages, judges said, that make it an appealing concept. It is lightweight and can be transported and deployed with simple robotics, then filled with water before the crew arrives. It incorporates materials extracted from Mars, and because water in the Ice Home could potentially be converted to rocket fuel for the Mars Ascent Vehicle, the structure itself doubles as a storage tank that can be refilled for the next crew.
Another critical benefit is that water, a hydrogen-rich material, is an excellent shielding material for galactic cosmic rays - and many areas of Mars have abundant water ice just below the surface.
Galactic cosmic rays are one of the biggest risks of long stays on Mars. This high-energy radiation can pass right through the skin, damaging cells or DNA along the way that can mean an increased risk for cancer later in life or, at its worst, acute radiation sickness.
Space radiation is also a significant challenge for those designing potential Mars outposts. For example, one approach would envision habitats buried underneath the Martian surface to provide radiation shielding. However, burying the habitats before the crews arrive would require heavy robotic equipment that would need to be transported from Earth.
The Ice Home concept balances the need to provide protection from radiation, without the drawbacks of an underground habitat. The design maximizes the thickness of ice above the crew quarters to reduce radiation exposure while also still allowing light to pass through ice and surrounding materials.
“All of the materials we’ve selected are translucent, so some outside daylight can pass through and make it feel like you’re in a home and not a cave,” Langley Mars Ice Home principal investigator Kevin Kempton said.
Selecting materials that would accomplish these goals was a challenge for materials experts.
“The materials that make up the Ice Home will have to withstand many years of use in the harsh Martian environment, including ultraviolet radiation, charged-particle radiation, possibly some atomic oxygen, perchlorates, as well as dust storms – although not as fierce as in the movie ‘The Martian’,” said Langley researcher Sheila Ann Thibeault.
In addition to identifying potential materials, a key constraint for the team was the amount of water that could be reasonably extracted from Mars. Experts who develop systems for extracting resources on Mars indicated that it would be possible to fill the habitat at a rate of one cubic meter, or 35.3 cubic feet, per day. This rate would allow the Ice Home design to be completely filled in 400 days. The design could be scaled up if water could be extracted at higher rates.
Additional design considerations include a large amount of flexible workspace so that crews would have a place to service robotic equipment indoors without the need to wear a pressure suit. To manage temperatures inside the Ice Home, a layer of carbon dioxide gas would be used as in insulation between the living space and the thick shielding layer of ice. And, like water, carbon dioxide is available on Mars.
It’s important, Kempton said, for astronauts to have something to look forward to when they arrive on the Red Planet.
“After months of travel in space, when you first arrive at Mars and your new home is ready for you to move in, it will be a great day,” he said.