PSTDL

Project Overview

The LusTR instrumentation suite consists of the PHCP, a vertical percussive motion stage for the penetrometer, a ground penetrating radar, and a robotic mobility chassis. A robotic chassis was used to simulate more realistic data collection operations and move heavy payloads. The vertical percussive motion stage to which the PHCP is mounted is similar to the TRL-6 TRIDENT drill hardware produced by Honeybee Robotics for the NASA PRIME-1 and VIPER lunar prospecting missions. Percussive action enables the PHCP to use far less energy, a fraction of the run time, and provide greater in-situ geotechnical data resolution than conventional static or dynamic cone penetrometers.

The PHCP instrument was produced in-house by the PSTDL. An array of heaters, thermal sensors, and force transducers are arranged in the PHCP cone head. Geotechnical properties of regolith including normal/shear stresses, friction angle, and cohesion as a function of depth are derived in-situ from percussing the penetrometer into the subsurface. Volatile type and concentration in regolith are derived by heating the cone head and observing the latent heat of phase change and other parameters.

A Ground Penetrating Radar (GPR) is used in tandem with the PHCP to estimate the spatial distribution of subsurface obstacles, layer stratification, and the presence of water ice. Thermal volatile, geotechnical, and radar data are then fused to decisively conclude where volatiles are, how concentrated the deposit is, and how difficult it will be to extract. Testing of the complete instrument suite and mobility platform successfully took place in February 2024 in 20,000kg beds of icy lunar regolith simulant. A second series of PHCP testing was completed in April 2024 inside a thermal vacuum facility, with cryogenically cooled icy regolith simulants.

CONOPS

The PHCP spot tests will be able to measure volatile composition and concentration in the test locations. Combined with high frequency ground penetrating radar to determine layers and continuity of the subsurface over large areas, this will allow horizontal and vertical spatial distribution measurements and identification of volatiles in the top 1 meter with a resolution of 0.1 wt% at 10 cm intervals as well as determination of geotechnical properties where PHCP spot tests are done. Research will consist of measuring thermal release profiles of cryogenic volatiles in regolith, GPR calibration of subsurface ice and layering detection, developing the differential calorimetry instrument and integrate it with the percussive penetrometer, testing and selecting the best cone geometry for geotechnical property determination, laboratory, DTVAC and field tests at Michigan Technological University and Honeybee Robotics of the PHCP and GPR to achieve TRL-5 or 6 by the end of the project. As such, PHCP and GPR could potentially fly on VIPER 2.0 in 2024 or 2025.