Numerical and Experimental Investigations of the Impact Dynamics of a Planetary Exploration Penetrator Probe

Abstract

Small penetrator probes have been proposed regularly as low(er) cost landing elements particularly for network science. This study reviews such a concept with regard to its soil penetration capability with numerical and experimental investigations. A reference micro Mars lander (MML) is considered to deliver a 10 kg payload to the Martian surface. It decelerates the penetrator probe with a mechanical decelerator to 40-60 m/s before impact. The remaining kinetic energy is distributed to the soil and an internal load limiter on impact, which restricts the maximum g-load acting on the payload. A semi-empirical force-displacement law and a discrete element simulation method were used to describe penetration behavior. Major impact force constituents are the velocity-dependent, drag-like displacement of the soil particles and the compaction of soil along the penetration path. Based on the simulation results, a test penetrator was designed and tested by impacting it on different soil conditions with a maximum impact velocity of 10 m/s. Cohesive Mars soil simulant, non-cohesive quartz sand, and stones of various sizes were used to assess different impact conditions. The comparison of test and simulation data identifies their respective capabilities and limitations. Recommendations for use and findings for further research are deduced therefrom.