Developing a High Fidelity Martian Soil Simulant Based on MSL Measurements: Applications for Habitability, Exploration, and In-Situ Resource Utilization

Powerful instruments, that include CheMin and SAM on the MSL Curiosity rover, have provided an unprecedented look into the mineral, chemical, and volatile composition of Martian soils. Interestingly, the bulk chemistry of the Rocknest windblown soil is a close match to similar measurements from the Spirit and Opportunity rovers, suggesting the presence of a global basaltic soil component. The Martian regolith is likely composed of this global soil mixed with locally to regionally derived components that include alteration products and evolved volcanic compositions. Without returned soil samples, researchers have relied on terrestrial simulants to address fundamental Mars science, habitability, in-situ resource utilization, and hardware for future exploration. However, these past simulants have low fidelity compared to actual Martian soils: JSC Mars-1a is an amorphous palagonitic material with spectral similarities to Martian dust, not soil, and Mojave Mars is simply a ground up terrestrial basalt chosen for its convenient location. Based on our experience creating asteroid regolith simulants, we are developing a high fidelity Martian soil simulant (Mars Global) designed ab initio to match the mineralogy, chemistry, and volatile contents of the global basaltic soil on Mars. The crystalline portion of the simulant is based on CheMin measurements of Rocknest and includes plagioclase, two pyroxenes, olivine, hematite, magnetite, anhydrite, and quartz. The amorphous portion is less well constrained, but we are re-creating it with basaltic glass, synthetic ferrihydrite, ferric sulfate, and carbonates. We also include perchlorate and nitrate salts based on evolved gas analyses from the SAM instrument. Analysis and testing of Mars Global will include physical properties (shear strength, density, internal friction angle), spectral properties, magnetic properties, and volatile release patterns. The simulant is initially being designed for NASA agricultural studies, but applications include studies of habitability, toxicity, and in-situ resource utilization, among others. Through a partnership with Deep Space Industries we intend to produce industrial quantities of Mars Global from consistently maintained feedstocks, making it available to researchers, engineers, and educators.