Last week, a family member (not involved in manufacturing) asked me what I knew about 3D printing. He’d seen the term in some online-story headlines, and heard a bit about it on the Discovery channel.

I explained that I had seen a few 3D printers in action, and that the process is really cool. He was impressed, to say the least. But, I didn’t stop there. I told him about a ground-breaking 3D printing application involving the European Space Agency (ESA).

For the past year, the ESA, in conjunction with London-based architectural firm Foster+Partners, has been performing tests to see if a Moon base can be 3D printed with local soil, rather than traditional thermoplastic. They call the soil "regolith."

Project scientists envision a large-format, robotic printer roving over an inflatable dome to build the base, which houses four people. Foster+Partners designed the base, which is a weight-bearing catenary dome with cellular structured walls that shield against micrometeoroids and space radiation. The agency is using the D-Shape printer, developed by Enrico Dini, in the project.

“As a practice, we design for extreme climates on earth and use local, sustainable materials,” says Xavier De Kestelier, associate partner—specialist modelling group for Foster+Partners. “Our lunar habitation follows a similar logic.”

To simulate lunar soil, Dini uses a mixture of silicon, aluminum, calcium, iron and magnesium oxide. To simulate the Moon’s surface, the researchers use a vacuum chamber. Thus far, they have 3D printed various wall sections. Once printed, each section is treated with a binding salt that makes the wall hard as stone.

“Our current printer builds at a rate of around 2 meters per hour, while our next-generation design should reach 3.5 meters per hour,” says Dini. “[We can] complete an entire building in a week.”

Applying the salt in a traditional fashion proved unsuccessful, because, in a vacuum, material boils away. So the researchers placed the nozzle within the simulated soil. Capillary forces in the soil keep the nozzle in place during application, notes Giovanni Cesaratti, proposal manager for Alta SpA, an Italian space research agency.

Scott Hovland, head of human systems for ESA, says 3D printing with local soil will dramatically reduce the amount of materials that need to be shuttled to and from the Moon.  It also will be much more efficient than catapulting thousands of pounds of building materials into orbit.