Construction on Mars or Moon will be possible, claims Behrokh Khoshnevis, professor of industrial & systems engineering at the University of Southern California and director of the Center for Rapid Automated Fabrication Technologies (CRAFT).
Prof. Khoshnevis has developed a 3D printing technology that is set to revolutionise construction on Earth, and make it possible in other planets and celestial bodies in the future.
Contour Crafting, invented 22 years ago, is a construction method that utilises 3D printing technology to construct large-scale structures directly from architectural CAD models, reducing construction costs, waste and time.
To print a house with this technology, a number of steps are required. Firstly, it is necessary to flatten the required space; then, with an excavator, create a trench for the foundation, which the machine fills with concrete; the contour crafter, which has a light weight, is then placed by workers on top of a pair of parallel rails and moves along the X, Y (horizontal plane), and Z (vertical) axes; finally, a fast drying concrete is pumped out of the contour crafter nozzle as the system carries out the construction of the house.
The difference between Contour Crafting and other 3D printing methods is clear for Prof. Khoshnevis. “Other 3D printing methods use very thin layers. If these methods use thick layers they would lose surface quality, surfaces would become rough, and you would get the ‘staircasing effect’. In contour crafting we have the mechanism to smooth out surfaces while depositing the material in thick layers.”
The technology is able to build a 185.81 sq m house, with all electrical and plumbing utilities, under 24 hours. Prof. Khoshnevis is now undertaking research with NASA, as part of the Innovative Advanced Concepts (NIAC) program, to be able to construct structures, possibly hangers for landers and later on homes, on Mars or Moon using the technology.
Contour Crafting can build a 185.81 sq m house under 24 hours.
This is supported by the goal of sending humans to other planets and celestial bodies. NASA expects to send humans to an asteroid by 2025 and Mars by 2030 — goals outlined in the bipartisan NASA Authorization Act of 2010 and in the US National Space Policy, also issued in 2010.
The US president Donald Trump has recently approved a bill authorising $19.5bn in funding for NASA — continuing to fund the construction of the Space Launch System rocket and Orion crew capsule mission. Mars One mission, a one-way trip to Mars, also aims to create a settlement in the red planet.
The idea of building outside the Earth was driven by the financial crisis in 2008, which greatly affected real estate and the construction industry. Prof. Khoshnevis recalls that during this period it was very difficult to get support to work on the technology and so he was forced to change the focus of his research.
He says: “I changed my focus towards other applications. That was when I approached NASA with the idea of building on the Moon and Mars without using any material from Earth, and just using in-situ material to build structures. I made some demonstrations on how one can make large concrete structures without the use of water and that began my project with NASA.”
The technology will possibly build hangers and homes on Mars and Moon.
But before approaching NASA, the professor hypothesised and made his own research on the material existent in the two celestial bodies.
“There’s a lot of science available and I also notice that there is similar material on Earth, they are called simulants. They are made for people who want to do research. I bought some of that material and I started to do my own experimentation with my own pocket money. It’s a lot of play inside your mind and then a lot of trials,” says Prof. Khoshnevis.
The impossibility of using water for the concrete was another question that needed to be addressed — there is water on Mars, but it is frozen beneath the surface and so very difficult to get it.
The professor thought about melting lunar dust and extruding it into the contour crafting system. “The flowing lava is basically melted rock and as you know when it cools down it becomes solid rock, so for the Moon that’s the concept that I thought about.”
And for Mars, sulfur will be used as a binder. An engineering team from Northwestern University has already created a Martian concrete using materials that are found on the red planet — soil simulant created by NASA and molten sulfur instead of water.
Now in Phase 3 of the work that he and his team are undertaking with NASA, research continues on how to get the ingredients needed from those materials, as well as on the logistics of building outside the Earth — how to take the material to the site and get it into the robotic machinery.
Other aspect of building on Mars or Moon is how to take the 3D printer from Earth and then into the site where construction will take place.
“There are a lot of complex issues to be resolved. It’s not a three-dollar task to go to another planet and autonomously build using only the material that is on that planet. There are a significant number of challenges that have to be overcome,” says Prof. Khoshnevis.
“Several other phases” of the research will be carried out in collaboration with NASA.
When will Contour Crafting be commercially available?
Sections and complete buildings have already been built with Contour Crafting along the years for ‘terrestrial applications’, as have been many different versions and generations of machinery — used only for demonstrations and research.
However, there was a major challenge impeding it from being available on the market: “The main challenge so far has been getting the right amount of funds to move forward. I started this concept much earlier than anyone else, when a lot of people didn’t know about 3D printing yet. I never felt that the time was right to launch this technology for commercialization, but now I have secured sufficient funds. Disruptive technologies have a hard time happening”.
Contour Crafting will be available for commercialisation by early 2018, while research on using this technology on Mars or Moon will continue.
Construction companies will be able to use Contour Crafting in 2018.
* For more information on the construction industry, visit the Construction Intelligence Center.