Entry of dust particles into planetary magnetospheres

While interplanetary dust constitutes a primary source of cosmic particulate matter in planetary magnetospheres, the debris produced by its impact with small satellites and ring material provides an important secondary source. Internal processes, such as volcanic activity, particularly in the smaller satellites, could result in a third source. In the case of the terrestrial magnetosphere there are also artificial (internal) sources: 1–10μ sized A?₂O₃ particles injected by solid rocket mortar burns between near earth and geosynchronous orbit constitute one such source, while the fragments of larger bodies (artificial satellites) due to explosions (e.g., “killer satellites”) and collisions constitute another. Finally, if we include the purely induced cometary magnetosphere among planetary magnetospheres, the injection of cometary dust into it due to entrainment by the outflowing gases constitutes another source.As a result of being immersed in a radiative and plasma environment these dust grains get electrically charged up to some potential (positive or negative). Particularly in those regions where the magnetospheric plasma is hot and dense and their own spatial density is low, the dust grains could get charged to numerically large negative potentials.While this charging may have physical consequences for the larger grains, such as electrostatic erosion (“chipping”) and disruption, it also can effect the dynamics of the smaller grains. Indeed, the small but finite capacitance of these grains, which leads to a phase lag in the gyrophase oscillation of the grain potential, could even lead to the permanent magneto-gravitational capture of interplanetary grains within planetary magnetospheres in certain situations. Here we will review the sources of dust in planetary magnetospheres and discuss their physics and their dynamics under the combined action of both planetary gravitational and magnetospheric electromagnetic forces.