Extraterrestrial rock mechanics and brittleness indices of simulated Martian rocks with implications for in-situ resource utilization on Mars

Brittleness Index (BI), while not universally standardized, is one of the most critical parameters in the assessment of rock failure behavior, drillability, and excavation efficiency in mining; however, its applicability to extraterrestrial environments remains poorly constrained for the In-Situ Resource Utilization (ISRU) mission on Mars. This study qualitatively and quantitatively investigated the mechanistic attributes (compressive strength, (Formula presented) ; tensile strength, (Formula presented) ) and BI of simulated Martian rocks under distinct conditions. Martian analog rock specimens, developed using Mars Global Simulant, were subjected to controlled bulk-scale mechanical tests (uniaxial compression and Brazilian disc tests) to determine (Formula presented) and (Formula presented), supported by SEM-EDS analyses, to validate mineralogical similarity with Martian samples. Results revealed that the simulated Martian rocks are representative of Jezero crater lithologies and exhibit behavior characterized by linear elastic deformation followed by abrupt failure under stress. A gravity-modified brittleness index (BI_M1, BI_M2, BI_M3, and BI_M4) was proposed, which yielded lower brittleness thresholds consistent with a mechanically weaker Martian lithosphere. Further, the Martian-specific brittleness classification indicated that the analog Martian rocks fall predominantly within low-to-moderately brittle categories (0.1<BI_M4<9.3) under Martian conditions, suggesting favorable drillability and relatively low energy requirements for excavation. These findings offer novel insights into the feasibility of predicting Martian excavation performance for ISRU.