Sample Acquisition and In-Situ Analysis Using the Ultrasonic/Sonic Driller/Corer (USDC) and Robotic Platforms

Future NASA exploration missions to Mars, Europa, Titan, comets and asteroids are seeking to perform sampling, in-situ analysis and possibly return of material to Earth for further tests. One of the major limitations of conventional drills when sampling in low gravity environments is the need for high axial force and, as a result, heavy robotic mechanisms, which constrain mission objectives. To overcome this and other limitations of existing drilling techniques, an ultrasonic/sonic driller/corer (USDC) mechanism was developed. The USDC is actuated by a piezoelectric stack, which drives an ultrasonic horn. The horn drives a free mass, which resonates, between the horn and drill stem. Tests have shown that this device addresses some of the key challenges to the NASA objective of planetary insitu sampling and analysis. The USDC is lightweight (<450 g), requires low preload (< 5N) and can be driven at low power (5W). The device has been demonstrated to operate from a Sojourner class rover and the FIDO robotic arm. In addition the device has been shown to drill various rock types including granite, diorite, basalt and limestone. The drill has the potential to be operated at high and low temperatures and does not require sharpening of the bit. The drill is driven electrically at 20 kHz, a substantial subharmonic acoustic component is present that is crucial to drilling performance. Analytical models that explain this low frequency coupling in the horn, free mass, drill stem and rock were developed and are currently being integrated and verified. The results of the USDC research and development efforts to date and the potential of the device will be described in this paper.