Compressed CO2 Hard Rock Drill for Mars

We have developed a down-the-hole (DTH) rotary-percussive drill prototype that could operate on compressed Mars atmospheric CO2 gas with a wireline drilling approach. This technology addresses a need for more aggressive sampling and drilling techniques, for both scientific purposes and to obtain In-Situ Resource Utilization (ISRU) resources for future NASA missions and human crew support. Using a spool of lightweight, high-pressure capillary, a DTH drill assembly would be moved in and out of the hole that could be a kilometer or more in depth. The CO2 drill is designed so that Mars atmospheric CO2 could be collected, compressed, and supplied down the hole and routed through microducts, valves, and reservoirs for the purpose of controlling miniature mechanical actuation in the assembly. By using compressed CO2, the drill system avoids the need for heavy electrical cabling and actuator systems or a liquid media for carrying away particulates as is typically used in terrestrial drilling systems. Instead, the liquid CO2 that powers the drill expands to a gas and could be channeled around the drill housing to carry cuttings to be collected in a bailing bucket. Where terrestrial systems often use drill depth vs time as a metric, a Mars drilling system would need to be extremely low mass, but would have no need to perform under tight schedules. In this paper, we will document our trade studies, progression for the design of microduct logic verified through multiple generations of prototypes, and provide predictive performance data on energy consumption, hole depth, and drill time. We have also applied the drill to an overall drilling system including delivery, deployment, and the material handling of cuttings away from the hole.