Electrostatics and Collision Dynamics of Ice and Anthropogenic Smoke Particles in the Mesosphere/Lower Thermosphere

Abstract. The increase in satellite launches raises the anthropogenic influx of various elements into the Mesosphere and Lower Thermosphere (MLT), comparable to the natural influx caused by meteoric ablation. This study investigates the electrostatic interactions between ice particles and remnants of space debris using a classical electrostatic framework. Aside from the Coulomb interaction, the attractive force between two particles at short distances, arising from polarization, is taken into account. Collision outcomes, the effective velocity regime for collisions, and the subsequent aggregation probability are estimated. Aggregation is limited to a specific range of collision velocities between minimum and maximum values. This range varies depending on factors such as particle size, mass density, and dielectric constant. For most particles, the aggregation velocities range from a few m s^-1 to several tens of m s^-1, where smaller particles may need significantly higher velocities to form stable aggregates. When considering the collisions of particles in thermal motion, it is found that Al₂O₃ (due to its greater abundance) and TiO₂ (due to its higher dielectric constant), both originating from anthropogenic sources, may dominate in the formation of ice-anthropogenic particle aggregates. In the MLT region, the formation of stable aggregates from the collision of ice with particles from space debris, which one may denote as anthropogenic smoke particles (ASPs), is similar to that from collisions with meteoric smoke particles (MSPs).