3D Printing Habitats on Mars Using Martian Regolith Simulant

Abstract

Limitations of manned missions include limited amount of payload that can be transported to the target body, and human vulnerability to harsh pressures, temperatures, and space radiation. Hence, it is preferable that the potential landing location for humans has an already constructed habitat preferably made from in-situ materials. This means that the prospect of utilizing a readily available Martian material, such as regolith, in an easily programmable manufacturing method, such as 3D printing, is very lucrative. The goal of this research is to explore a mixture containing Martian regolith for the purposes of 3D-printing in unfavorable conditions. Regolith has the properties that allow it to act as geopolymer in the presence of appropriate alkaline binder, and hypothetically a very low amount of such binder is needed. For the sake of this research, a simplified binder which consists of water and Sodium Silicate is used. Martian conditions are less favorable for the curing of such mixture because of low temperature and pressure on the surface of the planet. Manufacturing through 3D-printing, as compared to molding, might also have an effect on the resulting mechanical properties. In order to evaluate mechanical properties of the mixture, molding and 3D-printing was conducted at various curing conditions and the results were compared. Due to the combination of low reaction speed at low temperature (2°C) and rapid water evaporation at low pressure (0.1 - 0.01 bar), curing of the specimens at Martian conditions yielded unsatisfactory results. The reaction medium in the form of water was evaporated from the specimen before the curing reaction could progress enough to form a proper geopolymer. Most of such specimens were not robust enough to withstand the beginning of three-point bending test, yet alone to be used as a construction material. The specimens cured at high temperatures (60°C) showed satisfactory results, with highest flexural load achieved up to 9 MPa when cured at 60°C temperature and 1 bar pressure. The specimens manufactured by 3D-printing showed ultimate flexural stress 20% lower than equivalent molded specimens. Overall, the proposed mixture ended up being hardly suitable for the application in very low temperature and pressure conditions, because of its high dependence on elevated temperature and pressure for curing. Exploring potential mixture modifications and performing improved tests using the basis laid in this research might lead to a potentially effective and realistic way of utilizing Martian regolith for unmanned 3D-printing purposes with minimal investment, which is one of necessary goals in making a manned Martian mission possible.