Electrostatic Dust Lofting and Trajectories Near a Landed Spacecraft on an Asteroid

Electrostatic dust lofting has long been hypothesized to occur on the Moon and asteroids. In 2016, the patched charge model provided a new framework to predict the electric charge on regolith particles and the short-range electric field between particles. We have previously used this model to predict the size particles that could be electrostatically lofted from Bennu and the subsequent trajectories of lofted particles. The hazard of electrostatically lofted or levitating dust to spacecraft or instruments is frequently considered by the planetary science mission community. Additionally, the motion of dust in response to a spacecraft’s presence may influence the interpretation of landing site features. However, to date, few quantitative results on the behavior of dust due to the effect of a landed spacecraft on the local plasma environment have been published. In this work, we consider the motion of electrostatically lofted particles near a simplified spacecraft ~3m above the surface of a simplified, 2D model of Bennu’s equator. The plasma sheath is modeled numerically using a treecode. We consider two illumination conditions: high noon and approximately 5pm. A variety of particle launch locations are considered and trajectories are propagated for five minutes or until reimpact. We show that the presence of a spacecraft significantly influences the plasma sheath structure, as expected. Additionally, we see that negatively charged dust particles are repelled from the spacecraft and its plasma wake, decreasing the particles’ peak altitude and their overall mobility.