Geothermite Reactions for In Situ Resource Utilization on the Moon and Beyond

Utilization of in-situ lunar resources will decrease launch mass and thus the expense of missions to the Moon, and will also give a lunar base a degree of self-sufficiency. Geothermite© reactions utilize an in-situ mixture of minerals and a reducing agent as reactants in a thermite-type chemical reaction. The geothermite© reaction investigated within this study used a mixture of JSC-1A series of lunar regolith simulant and aluminum powder as reactants. The JSC-1A series of simulant is an approximation of chemical and mineralogical characteristics of actual lunar regolith. Upon application of heat, an exothermic reaction initiated, and a coherent ceramic-composite material was produced. Experiments have shown that a geothermite© reaction occurred within the regolith-aluminum mixture over a range of reactant proportions. XRD analysis indicated that silicon, corundum (Al₂O₃), grossite (CaAl₄O₇), and spinel (MgAl₂O₄) were common species present in the reaction product. SEM/EDS analysis of samples reacted in a standard atmosphere showed formation of nanoscale whiskers containing aluminum, oxygen, and nitrogen. XRD results indicate that the whiskers are likely to be composed of aluminum oxides and aluminum nitrides. The compressive strength of products formed in a standard atmosphere was observed to vary depending on reactant proportions and particle size of the simulant. The largest mean compressive strength was found to be 18 ± 3.7 MPa. To better simulate conditions on the lunar surface, further experiments were conducted in a vacuum environment. No whisker formation was observed within samples reacted in a vacuum environment. It is hypothesized that the removal of gases by the vacuum environment decreased overall interparticle contact by preventing solid-gas chemical reactions. Neutron radiation transmission measurements were conducted on two samples to determine the preliminary radiation shielding capability of the reaction product.