Engineers and students grapple with 3-D printing a habitable structure on Mars

Engineers and students grapple with 3-D printing a habitable structure on Mars
Mars habitat designed by MIT faculty and students

We are in the midst of a "Mars moment." This fall, the Matt Damon film, "The Martian," a story about a stranded astronaut who must learn to survive on Mars, grossed a whopping $55 million at the box office in its opening weekend. The same week, scientists breathlessly revealed the discovery of liquid water on Mars, raising the possibility that life might yet exist there.

But what would it actually take to support human life on the Red Planet?

An MIT group including 10 students took up the challenge to answer that question last month in a competition co-sponsored by NASA to build a habitat that could be used on Mars in just 20 years—in 2035. "That is a pretty aggressive timetable," notes Caitlin Mueller, an assistant professor in building technology and director of the Digital Structures group—all the more so since the distance to Mars and the fuel required to get there means travelling as light as possible.

In order to cut down on transport costs, NASA is pushing the use of 3-D printing technology using indigenous materials. The "3-D Printed Habitat Challenge," also co-sponsored by the National Additive Manufacturing Innovation Institute (known as America Makes), offered $25,000 to the winning design at a competition at the New York City Maker Faire on September 26-27—part of a $2.25 million challenge over the next few months.

"Thinking about it was really fun because you really are starting from scratch," says Mueller. Mars has only a third of the gravity of earth, and temperatures of below zero for most of the year. The biggest issue, however, was the lack of atmosphere, which means that any structure will have to be massively pressurized from within to withstand the vacuum of the space.

Far from discouraging team members, those limitations stoked their creativity. "Paradoxically, being in an alien environment in the future frees us up to be a little more conceptual," says Justin Lavallee, technical instructor and the director of the Architecture Shops at the School of Architecture, who collaborated with Mueller on the project. "We can be a little more exploratory without being so bogged down in current understanding of what will and won't work in architecture."

Engineers and students grapple with 3-D printing a habitable structure on Mars
Mars habitat designed by MIT faculty and students

Mueller has been experimenting with new methods of 3-D printing that follow the stress-lines of structures rather than printing in horizontal layers. Lavallee has been working with new thermoplastic composite materials. Together, the two pooled their expertise to create a 3-D printer that could pull the composite material through a nozzle and shape it while weaving it together with fiberglass to give the form strength and shape.

Mueller and Lavallee were helped in their task by students in disciplines ranging from architectural design to computer engineering. "It wasn't just us teaching them how to build a structure on Mars, because none of us know how to do that," says Mueller. "We were figuring it out together." For inspiration, students watched science-fiction films including "2001" and "Gravity," as well as episodes of the futuristic British series "Black Mirror," says master's of architecture student Nicole Ashurian. "They were great inspiration, but they were scary too," she says. Confronted with the vastness of space, the group placed emphasis on creating a habitat that would be equally comfortable as functional. "We decided we needed to bring some humanity to Martian space," she says.

They settled on a toroidal form—in lay terms, a donut—that could both be evenly inflated with pressurized air, and also form continuous living environment with spaces for privacy. While Ashurian has been developing experience designing structures, the Martian environment was a drastic departure from the usual site challenges. "You have minor variances sometimes, up in the mountains, or where it's really hot, but never do we have to question the atmosphere," she says. "We were really dependent on the engineering students to help fill us in."

One of those students, undergrad Mitchell Gu, who majors in electrical engineering and computer science, was instrumental in providing the technical analysis to prove whether the design and construction was feasible. "One of the concerns we had was that the sand on Mars does not contain enough silica to create glass," he says, by way of example. Luckily, the team was able to find a spot on the Red Planet nicknamed Silica Valley, where a Mars rover had found more than 60 percent silica in the soil. Gu and the other team members found a way to synthes ize the polypropylene needed to make the thermoplastic composite form hydrogen and carbon dioxide in the Martian atmosphere.

The team pulled all of their collective knowledge into a presentation for a design they called Ouroboros, after the Ancient Greek symbol of a snake eating its tail, and featuring illustrations that would be at home on the cover of an Isaac Asimov novel. "It was somewhere in-between working on a science fiction book and an architectural design competition, with some real engineering computation as well," Mueller says. "It was really like what MIT is all about," she adds, "bringing together many different areas of expertise to create something really innovative."

The second stage of the contest submission involved creating a model of the habitat. Lavallee pulled out all the stops in the architecture shop, machining metal, sandcasting aluminum, and printing thermoplastics to approximate the structure. "Many of the projects we work on focus narrowly on one tool or one machine," he says. "This was exciting because it demonstrated how we could bring all of our capabilities to bear."

Engineers and students grapple with 3-D printing a habitable structure on Mars
Mars habitat designed by MIT faculty and students

Finally, the moment of truth came when the team headed down to New York to face off against some 30 other designs—most of them by professional architecture and design firms.

In fact, of the 41 students who took part in the competition, nearly a quarter of them were from the MIT group. Undergraduate and graduate student members of the MIT team are: Nicole Ashurian,Ethan Bian, Alexandros Charidis, Chrystal Chern, Sean Phillips, Minxuan Gu, Sayjel Patel, Samuel Schneider, and Stavros Tseranidis.

When all of the space dust had settled, another design was chosen for the $25,000 prize. But that doesn't mean that the experience didn't have value, says Mueller. "Of course, we are disappointed that we didn't win, but pretty quickly in the process, it became more than just about winning this particular prize," she says.

Both she and Lavallee developed ideas about 3-D printing that they are planning on implementing in their own research and teaching. "Thermoplastics are the future of composites," Lavallee says. "It was exciting to get some hands-on experience with this new system." And they are already considering entering the next two phases of the competition to create full-scale structural components and an entire habitat, each of which includes $1.1 million in prizes.

For team member Mitchell Gu, meanwhile, the competition has inspired loftier dreams. The experience ignited his own love of space to cause him to consider a career in interplanetary architecture that may one day find him building on the Red Planet for real. "It made me realize that perhaps there is a new Mars age we are entering similar to the Moon Age," Gu says. "That is something that would be really special to be a part of."


Explore further

NASA challenges designers to construct habitat for deep space exploration

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Oct 16, 2015
I don't understand why the 'dig down' (or for the poles the 'melt down') options aren't explored. The amount of material needed for a habitat would be far smaller (OK, so you need a bit of heavy machinery. But weight scales linearly with building material if you print/construct but less than linearly with digging machinery it makes more sense the bigger you want your installation to be to go digging.

Especially in light of radiation levels on Mars digging down should be first choice. You also don't have as much issues with pressurization. A very light weight coating panel (or even just an airtight, sprayed-on mass) would suffice.

Oct 16, 2015
There are several critiques I see with this design right away:

Airlock/door...you need at least two of them in case one is damaged. there must always be at least two exits from every module, and if an intermediate module becomes damaged and unusable, there must be a way to go outside from say Module A, skip damaged module B, and re-enter module C while you are working on repairs for module B.

This is required. If you only have 1 airlock and it malfunctions, you are screwed.

Modularity: The entrance to the habitat with this design is not easily extended to connect to additional modules. I know there are issues of shielding the doorway from dust so the seals don't get screwed up, but the way to do that is to have a double- 90 degree angled dust shield*, which is removable when adding new modules.

Science fiction isn't a good place to draw inspiration, because everything is overly idealized and simplistic compared to what a realistic habitat would need to be.

Oct 16, 2015
*The dust shield I mentioned above is something I solved a few years back. You have a tunnel which extends beyond the airlock and turns 90 degrees along-side the habitat for a few meters, then turns another 90 degrees back away from the habitat, and goes out about a meter or two. This will help prevent dust from interfering with the seal on the airlock. It is not perfect, but it's a lot better than nothing.

It would still be a good idea to have an (outside) air compressor and hose with nozzle to spray the dust out of the seals just in case.

Another option would be to use triple-walled airlocks instead of double-walled airlocks, and still use compressed CO2 (from outside atmosphere) to blow the dust out of the seals as you open and close each segment.

Oct 16, 2015
Oh, forgive me for the "crime" of offering constructive, corrective critique of the problems these idealists overlooked.

I'm the son of a carpenter and grand-son of an off-shore mechanic. I've actually built things with my own two hands for decades, since I was about 8 or 9 actually (house fire involved)...

These people probably haven't built anything "real" in their lives, degree or no degree.

These silly idealistic designs, proposed by literally every team I've ever seen, are good for getting people killed, and not much else.

I've already solved problems these babies and their idiot professors haven't even realized exist.

Oct 16, 2015
Have no idea who here does not 'like' you, but your idea does have some merit so 'upped' your score. We have codes here for fire prevention called NFPA-101; they REQUIRE multiple exits from structures based on number of people inside and space, flammability of construction. OK, we are using an organopolymer as a building material and ALL of these have some flammability. Fire killed an entire Apollo crew once, killed them quickly, and no rescue was practical given the one entrance design and other design features. Now MIT wants to learn nothing from this and 'do it again'. Anti-Alias' idea of "diggin' in!" is a good solid one. No sudden decompression because some clumsy furniture or other move put a sudden hole in the structure and a sudden end to the colony soon after. More space underground anyway and quite expandible as long as one can dig and dispose of the dirt or use it.

Oct 16, 2015
"From Dream to Reality" was a motto of one of my old military units. Guess we made some architects a bit sad when they were told their designs were impossible without practical changes. What MIT wants here is a tent. I lived in tents when camping, and disaster victims live in tents. NONE DO IT PERMANENTLY unless they are aborigines. WE need to make our own cave to shield us from radiation. We need large rooms in that cave to park and maintain our outside vehicles in a shirt sleeved atmosphere so our maintainance weenies can do WORK instead of worrying about being killed by a pinprick in their precious expensive and impossible to replace golden heavy and cumbersome spacesuit, required wearing while outside. We need a massive steel reinforced synthconcrete and steel rimmed and doored outer door with an inner lock door to match and a floor that bears the weight and repetitive stress of our heavy equipment, including exploration crawlers. Hey 'dis place ain't no fairyland!

Oct 16, 2015
Once supervised a pool construction job and saw an old 'aluminum shell' pool that its original installer claimed great things for.!.... Oversaw the removal of the swiss cheese like wreck of what was left of it after natural processes and the failure of various 'wonder coatings' due to mechanical flexure, hydrostatic stress, Cl2 infused water, soil chemicals, etc. did to the aluminum (Al is a member of the Alkaline Earth metals and verrry reactive, not found free in nature but that was astonishingly overlooked). Reeeplaced that 'pool' with a 'gunite' pool. We put in a pattern of re-inforcing stainless steel and sprayed a form of concrete called "Keene's Cement" on it with a nice simple nozzle until we had all covered, and then troweled and power troweled the result before spray coating with epoxy layers. Every part of it impervious to water and resistant to chemical action. Such would make good sealer for the walls, ceilings, and floors of our Mars cave. Secure place!!

Oct 16, 2015
We are finding that all our planets are made of much the same stuff. Even Mercury, the core of a planet that lost its outer layers likely in a huge collision with a larger body that kept much of its outer mantle for itself.....'Thera anyone'. Mercury will likely become the precious and/or rare earth metal source for the whole colonized solar system but that is another project. Project Mars will find that that red color probably means iron...there is our re-bar. All that silica and sand and aggregate...there is our concrete. Make that plastic...there are our forms. Create water from atmosphere and regolith...there is our admixture. Furniture and dishes, other stuff can all be made from the plastic mentioned in article above. There is little in the world of ideas OR materials that are worth NOTHING. First thing the military and my country boy upbringing ever taught me.

Oct 16, 2015
I have another suggestion. Lets figure out how to capture carbon from the atmosphere on Mars (fairly easy to do) and use it to make these fibers for construction and pretty much whatever else you can imagine.
https://www.youtu...JC64tDR0
Rice University has the answer! Imagine if the fibers in a fire hose were made of these instead.

Oct 16, 2015
If there was flowing water then perhaps they should be looking for caves as initial habitats.

Oct 16, 2015
There are already known caves and tunnels on the Moon & Mars, lava tubes. Some appear to have been stable for billions of years, they would act as a radiation shield and provide a stable temperature. NASA have already conducted studies into using them as a base.

Oct 16, 2015
Lets figure out how to capture carbon from the atmosphere on Mars (fairly easy to do)

I dunno. at 1% Earth atmospheric pressure the atmosphere on Mars does not contain significantly more carbon dioxide than Earth atmosphere per volume unit. So the difficulty would be about the same as doing this here..

Oct 16, 2015
I imagine this is more in the research phase than the actual design phase. More of a "can we print an airlock" than a "how should the airlock be printed" kind of thing. It seems the focus is more on technique and materials.

Personally, and this really has no place in scientific consideration, buuuut, personally I'd rather not travel all the way to a new planet just to never see its sky. If it takes extra materials and a Hyrdroplasmarc(TM*) shell to keep out the radiation and still be a window to the surface, so be it! Completely cost-hostile aesthetic choice right there.

*trademarked technology does not exist, is completely made up word

Oct 19, 2015
I agree with superthunder, this seems to be reporting on a think-tank like approach to Mars Habitat design. Out of the whole article, the only part that really reported on anything new was:

Mueller has been experimenting with new methods of 3-D printing that follow the stress-lines of structures rather than printing in horizontal layers.


That sounds interesting.

I also like everyone's idea to dig into the ground, that seems to make the most sense as you can build much larger structures just by removing material. Couldn't they dig down in the "Silica Valley", and just use a really powerful blowtorch type device and create glass tunnels? Seems feasible.

Oct 19, 2015
Couldn't they dig down in the "Silica Valley", and just use a really powerful blowtorch type device and create glass tunnels?

The issue with the dig/melt approach seems to me: power.
What kind of powerplant would be needed to achieve digging/melting in a sensible timeframe?

For melting I suspect solar power (planet based or in orbit) would be sufficient. The surface based operations would not require particularly sophisticated robotics as melting CO2 does not even require contact. Maintenance issues on such a robot would be close to zero. (Drawback is that your habitat is surrounded by CO2 ice - which would pose a serious (hard to detect) health hazard in case of a leak. Not an insurmountable obstacle, but something to keep in mind.

Digging requires more power than, I feel, solar cells would be able to provide. Which means some sort of nuclear power would be required (and that'd be a very serious - read: heavy - piece of equipment to land safely on Mars)

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