ABSTRACT
The acquisition of rock and soil samples plays an important role in NASA’s space exploration missions. Tools capable of coring, drilling, and abrading are necessary for exposing fresh rock sample or sampling for in situ instruments or sample return. Due to the energy/power and mass constraints of planetary missions, high power consumption as is found in conventional drills is extremely undesirable. In order to address these contraints a piezoelectric-driven Ultrasonic/Sonic Driller/Corer (USDC) mechanism has been developed for planetary sampling. The USDC is a solid-state hammering mechanism that uses ultrasonic displacements to create larger-stroke percussive displacements. Inside the USDC, a piezoelectric stack generates vibrations that propagate and are amplified via a horn and the vibrations impact a free-flying mass. The mass then impacts a drill bit introducing stress pulses onto the bit/rock interface, which produce stress pulses that exceed the ultimate strain of the rock that it is in contact with and fractures. The USDC’s key benefits include being lightweight, requiring low axial preload, and its ability to be configured as an in situ analyzer (Bao et al., 2003; Bar-Cohen and Zacny, 2009).
