SPATIAL MAPPING OF GEOMECHANICAL GRADIENTS USING SPARTA

It is essential to understand the mechanical properties of planetary regolith and identify the presence and chemical potentials of water and ice for the success of future planetary landed science missions. NASA has developed SPARTA (Soil Properties Assessment, Resistance, Thermal, Analysis) to address this need. This versatile toolkit includes a cone penetrometer/vane shear mechanical tool with a dielectric probe and thermal conductivity measurements for depths less than 15 cm. These measurements provide an instantaneous subsurface analysis, helping identify key geomechanical parameters for future human and ISRU exploration.

Recently, we collected SPARTA probe data from lake bed deposits near Lava Fields National Park in northern CA to demonstrate the toolkit's spatial mapping capability for subsurface 3D reconstruction. We used the SPARTA toolkit to evaluate the mechanical properties of the lake’s near-surface regolith using two complementary component sensors: the VST, which measures soil shear strength, cohesion, and angle of internal friction, and the CPT, which measures compaction, relative density, and pore size distribution. The combined measurements of VST and CPT provided a detailed analysis of the mechanical properties of the lake deposits. This study illustrates SPARTA’s ability to collect crucial data for creating 3D maps of the mechanical and environmental properties of the shallow subsurface of the lakebed deposits, identifying spatial gradients in the subsurface.