Nervous about your upcoming stay in an inflatable space station? Want a bit more than some plastic between you and the vacuum of space? The European Space Agency (ESA) is here to help! They are putting together preliminary plans to build structures on the Moon using the combination of inflatable compartments and 3D printers. These buildings would be far more durable than just an inflatable structure and easier to make air-tight than one lacking the inflatable part entirely.
3D printers are just emerging into the mainstream here on Earth. Depending on who you ask, they are either a fun tool for hobbyists or the next invention to change the world. They allow any object to be built layer-by-layer by depositing micron-thick layers of material from a moveable nozzle. Consumer versions typically build with plastic, but professional ones can even construct objects out of metal. Because they don't require a template or mold, 3D printers allow remarkable flexibility in fabrication.
You might be thinking that a plastic building doesn't sound that much better than an inflatable one, and that hauling tons (literally!) of metal to the Moon doesn't sound that economical. That's where the most innovative part of the ESA plan kicks in. The 3D printers won't be using plastic or metal, but Moon rocks. Just like soil on Earth, the surface of the Moon contains many useful elements, including potential building materials such as aluminum and magnesium. These metals could be extracted from the surface material and fed into the printers. The printers would then cover the exterior of an inflatable module wit ha protective coat. Imagine covering an inflated balloon with clay: even if you deflate the ballon, the clay will retain its shape.
Utilizing the resources of a destination world isn't a new idea. Research conducted over the past decade has suggested that chemicals extracted from the air and soil on Mars could be used to create the rocket fuel needed for the return trip home. Such a process would greatly reduce the amount of mass a mission to Mars would need to launch off the Earth's surface. It could also provide fuel to power experiments and habitats once the astronauts arrive. An interesting byproduct of this reaction? Oxygen - another payload which would weigh quite a lot.