3D Printing Lunar Habits using Lunar Regolith Simulant

For my senior capstone project, I proposed a 2 component project, developing a 3D Printer to print lunar habitats and a compatible material that dramatically lowers the cost while maintaining strength requirements and printability. This is a 2 semester project that is projected to be completed in Fall 2024. 

View our team's final design review here. Note: this is not the final design as changes will be need to made prior to and during fabrication. 

The printer is inspired by a traditional fused filament fabrication (FDM) 3D printer with a build plate, pseudo nozzle, extruder system, and full 3-axis movement. The material is formed using lunar regolith simulant, a fine powder primarily composed of silicon dioxide (silica) and aluminum oxide (alumina). To solidify this powder into usable material, concentrated sodium hydroxide is used as a geopolymerization agent. 

Developing the  Material

Geopolymerization is a process in which the hydroxide group in chemically basic solutions interact with the silica inside a base material. On Earth, this is often used in small concrete applications, and offers substatial streingth values, reaching upwards of 35-40 MPa. For reference, the American Concrete Institute (ACI) recommends buildings on Earth at least 30 MPa of compressive stress. On the lunar surface, structural loads are reduced by a factor of 6 (down to 5 MPa) due to the reduced gravity.

Another process that the team researched and developed is a UV resin process in which specialized resin is used as a photopolymerization agent to solidify the resin and regolith mixture. This method utilizes a similar FDM technique with the help of a low power laser which serves to cure the resin in the mixture.  The resin has monomers and catalysts that to UV radiation exposure which begins a process to combine monomers and form high strength polymers.