Processing and optical properties of Martian regolith for solar energy applications

In-situ exploitation of Martian resources to obtain products and services is crucial for promoting future manned missions on the planet. Along this line, the JSC-Mars-1A, and MMS regolith simulants which are representative of the wide spectrum of soils available on the Mars surface, are investigated in detail to evaluate their possible utilization for solar energy applications, when used either in powder form or after being consolidated by Spark Plasma Sintering (SPS). The markedly different densification behavior shown by the two simulants can be associated with their diverse compositional and structural characteristics, with the predominant amorphous constituent (about 50 wt.%) in original JSC-Mars-1A observed to strongly favor powder consolidation. For this system, fully dense samples were obtained by SPS at 1000°C/3min/30MPa. Concurrently, the amorphous fraction was reduced to 16 wt.%. In contrast, the highly crystalline nature of MMS (70 wt.% of Andesine, only 3 wt.% of the amorphous content) makes this simulant more thermally stable and less prone to be consolidated, with 97.5% dense samples produced by SPS at 1050°C/3min/30MPa. To assess the samples’ solar absorption and thermal radiation properties, optical spectra of both simulants in the range from 0.2 to 16 μm wavelength were compared by considering pristine powders and bulk samples with different porosity and roughness characteristics. We found a significantly increased solar absorptance in the sintered samples with respect to the starting powders, even reaching the remarkable value of 0.93. The thermal emittance of ceramics was lower than that of powders for temperatures below about 300K, and superior for higher temperatures. These results have been discussed regarding the possible application of solar energy harvesting and thermal energy storage. • Mars regolith simulants JSC-Mars-1A and MMS are processed into bulk ceramics using Spark Plasma Sintering • Samples with different densities are obtained in different sintering conditions. • Composition, microstructural and optical properties are assessed. • Solar absorptance and thermal emittance of sintered pellets and native powders are compared. • Solar absorptance of bulks is remarkably higher than powders • Thermal emittance is lower for T<300 K and higher for higher T • Results are discussed for ISRU-based solar energy harvesting and thermal energy storage