Sampling of Regolith on Asteroids Utilizing Electrostatic Force

To achieve reliable and autonomous regolith sampling on asteroids, we have developed a unique sampling system that utilizes electrostatic force. When a rectangular high voltage is applied between parallel screen electrodes, the resultant Coulomb force and dielectrophoresis force act on particles in the vicinity of the electrodes, and some particles are captured passing through the openings of the screen electrodes. The sampling system is simple, has low power consumption, and has no mechanical moving parts. It was demonstrated that a lunar regolith simulant can be captured in a zero-G environment reproduced by the parabolic flight of an aircraft. As predicted by a numerical calculation utilizing a hard sphere model of the three-dimensional Distinct Element Method, a large amount of lunar regolith simulant, approximately 900 mg, was successfully sampled. The captured regolith particles contained not only small particles but also large particles more than 0.5 mm in diameter. Moreover, it was predicted by the numerical calculation that the sampling system would perform much better in a vacuum than in air.