Modeling of particle flow due to ultrasonic drilling

In-situ sampling and analysis is one of the major tasks in future NASA exploration missions. It is essential that the samples acquired on other planets including Mars are free of contaminations from the earth. Recently, a novel drilling technology that is actuated by a piezoelectric drive mechanism was developed and it is called Ultrasonic/Sonic Driller/Corer (USDC). This drill has an inherent capability to extract the formed drilling powder and thus addresses the critical issue of contamination. A modification of this USDC in the form of an Ultrasonic Rock Abrasion Tool (URAT) allows for the formation of pristine rock surface for analysis. An algorithm is being proposed for the reduction of the contamination that may be generated during the acquisition of the samples. The algorithm could be used to control the flow of particles using programmed vibration characteristics and thus allows for smart flow of particles. The hypothesis is that the probability of a contamination left on the ground surface is exponentially inverse-proportional to the volume of the core ground into dusts. To support this hypothesis, we need to understand the flow pattern of the particles. A model proposed by Savage [1988] is used to develop a computer program using finite difference method. Some preliminary results have been derived.