Sampling of Regolith on Asteroids Using Electrostatic Force

The authors have developed an electrostatic force-based sampler to reliably and autonomously sample asteroid regolith. After applying a rectangular high voltage between parallel screen electrodes mounted at the lower end of a tube, the resultant electrostatic force acts on nearby regolith particles. Some agitated particles are captured when passing through the screen electrode openings and transported to a collection capsule through the tube. In a microgravity environment, effective particle sampling was expected because particle motions are not affected by the negligible gravitational force. The authors confirmed the sampler's performance in a microgravity environment through numerical calculations and a model experiment. The calculation using the distinct element method predicted successful regolith capture, including conductive and insulative particles, under air and microgravity. The sampler shows much better performance in vacuum than in air. Lunar regolith simulant was sampled experimentally in a zero-g environment reproduced by the parabolic flight of an aircraft. A large amount of simulant (∼900 mg) containing small and large (diameter: >0.5 mm) particles was successfully collected.