Testing of a Bucket Ladder Excavation Mechanism for Lunar Applications

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Bucket ladder excavation systems are a potential solution on the Moon for excavation of granular or lightly cemented regolith for the purpose of in situ resource utilization (ISRU), construction, and subsurface science applications. This type of mechanism can continuously excavate and transport material at high excavation rate and low power use. However, there are more potential mechanical failure points in bucket ladders mechanisms when compared to other excavation systems for the Moon. Bucket ladders are the most popular excavation mechanism for the NASA Lunabotics mining competition and all winners have used a version of the bucket ladder. Previous testing of lunar bucket ladder prototypes has shown excavation rates larger than 1,000 kg/hr at a 0.01 W/kg/hr power level in atmospheric testing, but more information is required to understand the behaviour of complex excavation mechanisms under realistic lunar environmental conditions and using lunar regolith simulants. This research effort focuses on raising the technology readiness level (TRL) of bucket ladders to TRL-5/6 for lunar applications. A bucket ladder built in the Planetary Surface Technology Development Lab (PSTDL) at Michigan Technological University (MTU) is tested in a dusty thermal vacuum chamber at MTU to assess performance during extended operations. Wear on components, excavation forces, excavation rate, and power consumption are monitored. This paper will describe the bucket ladder excavation system, test setup, and preliminary results of this ongoing project. Collected test data will provide insight to the efficacy of using bucket ladders for lunar construction and ISRU as well as explore wear and tear observations.