CHARACTERIZING THE IN SITU GEOMECHANICAL PROPERTIES OF PLANETARY REGOLITH—SPARTA

In-depth characterization of the subsurface properties of in situ planetary regolith (e.g., environmental and geomechanical properties) is essential to many areas in planetary science, astrobiology, space engineering, and the operational success of all future landing missions involving surface or near-surface contact. Determining the presence of water/ice as well as the validating of future rover concepts and operations will rely on a comprehensive examination of in situ planetary regolith. For engineering, designers of landing systems, such as pads, airbags, and braking rockets, require an understanding of how their hardware will interact with the regolith. For example, estimating how rover mobility is affected by traversing on loose, granular regolith remains challenging. Although it is relatively straightforward to calculate the forces imparted on the terrain by rover hardware, characterization of the terrain response and its effect on trafficability has proven to be more difficult. Future rovers' wheels must be better designed to optionally engage the heterogeneity of bearing strength and the roughness of the surface to be traversed. At the same time, protecting moving parts against fine grained particles in the regolith is a major challenge for hardware on most planetary surfaces. Understanding the environmental properties (e.g., water/ice content) of in situ planetary regolith is critical for science and In Situ Resource Utilization (ISRU) evaluations. SPARTA (Soil Properties Assessment Resistance and Thermal Analysis) is a toolkit designed to analyze the in situ geomechanical properties and the ice content of planetary regolith, including the relative density and thermal gradient at specified increments with depth. The miniaturized SPARTA toolkit encompasses four terrestrial regolith components, each at or above a NASA Technical Readiness Level (TRL) of 4. The toolkit consists of a Thermal Conductivity Probe (TCP), a Vane Shear Tester (VST), a Cone Penetration Tester (CPT), and a Dielectric Spectroscopy Probe (DSP) designed for a variety of planetary surfaces; for bodies as diverse as Trojan asteroids, Mars, Titan, Moon, and Ocean World bodies (Planetary Science Decadal Study, 2022).