Electrostatic Levitation on Atmosphere-Less Planetary Bodies with Ionic-Liquid Ion Sources

Abstract

This paper presents an initial feasibility study on the use of ionic-liquid ion sources for electrostatic actuation on atmosphere-less planetary bodies. The natural surface charging of atmosphere-less planetary bodies has been studied as the cause of the transport of regolith across the surface and for electrostatic levitation of a spacecraft in proximity to small asteroids. The low magnitude of the natural surface electric field (order 10 V/m) severely limits the capability of a vehicle to leverage electrostatic levitation as its maneuvering strategy, particularly on large planetary bodies such as the Moon. Ionic-liquid ion sources are considered as an actuator for charging of both the vehicle as well as the local surface of the planetary body. By irradiating the surface with ions, the surface electric field can be increased far beyond its natural value and could enable electrostatic levitation on planetary bodies as large as the Moon with current technology. A low-fidelity analytical model of the charging process is developed in order to estimate requirements on the local surface charge density and limitations on the vehicle's levitation height and translational speed. Experiments are conducted in a laboratory environment to demonstrate the feasibility of using ionic-liquid ion sources for combined vehicle and surface charging by creating a 1 mN electrostatic force through charge transport while requiring only 0.2 mW of input power. These experiments are in reasonable agreement with the low-fidelity model that describes the fundamental physics of this concept.