Development of a Heuristic Thermal Control System for the Ultrasonic Planetary Core Drill

The Ultrasonic Planetary Core Drill (UPCD), recently developed by a consortium of European partners with co-ordination from the University of Glasgow, is a planetary sample acquisition and caching systems testbed, recently field tested at Alexander Island, Antarctica. During the early development of the technology, laboratory-based drilling tests at ambient pressure, utilizing volatile-laden permafrost simulants, revealed the need for an enhancement of the existing control algorithm which autonomously governs the rate of progress of the drill through the terrain. Such modifications have been deemed essential if failure modes relating to re-solidification of unbound volatiles are to be avoided. In the preliminary development of this thermal control algorithm, multiple sensors have been utilized in order to enhance the reliability of the system. It is hoped that this sensor suite may also allow data concerning the thermal environment of the terrain to be exploited, improving the scientific return of the mission. This paper details the early progress made towards a robust thermal control system for the Ultrasonic Planetary Core Drill, featuring results of laboratory testing under ambient conditions in to targets consisting of simulated permafrost, pure ice and frozen saturated rock. Results from this series of preliminary tests show that, when required, the control algorithm developed has proven to be a useful addition to the UPCD control system through its ability to prevent freeze-in faults.