Percussive Dynamic Cone Penetrometer for Geotechnical Surface Assessment with a Planetary

Introduction: During the past planetary surface missions, few instruments have been deployed to directly assess soil physical properties like density, soil strength (internal friction and cohesion), and pressure/sinkage curves, or their spatial variation. Several Soviet lunar missions were equipped with small cone vane penetrometers, and the Apollo astronauts also used two different manual penetrometers. For the most part, information on soil mechanical properties has been inferred from instruments intended for other purposes, such as landing pads, scoops and rover wheels. These measurements were difficult to interpret because of the complex test geometries, low signal resolution, and difficulty in determining forces and torques. Near term lunar missions will need to characterize subsurface for a variety of reasons. This includes predicting trafficability for the mobile planetary platforms, excavation forces and power for In Situ Resource Utilization (ISRU) and any form of planetary construction (habitats, landing zones etc). Methods of Assessing Soil Properties In-Situ: The cone penetration test is widely used in the geotechnical engineering field to measure in situ soil properties and to determine the variation of soil properties as a function of depth. These measurements are used to provide data for the design of structural foundations, pile foundation, and (near-surface) vehicle mobility predictions.