On Ion-Acoustic Precursor Soliton Signatures of Orbital Debris in Low Earth Orbit

Nonlinear plasma solitons have been recently proposed as a possible, indirect way to detect dangerous small orbital debris in low Earth orbit. A kinetic simulation study of the interaction between small debris flowing through a plasma at hypersonic velocity is presented, with a particular focus on whether the debris–plasma interaction leads to the formation of ion-acoustic precursor solitons. By using an electrostatic kinetic model and in the absence of an external magnetic field, simulation results where the debris is treated as a Gaussian density source are compared with those where the debris–plasma interaction is modeled self-consistently, in both one and two dimensions. While ion-acoustic solitons are formed when the debris is treated as a Gaussian density source and the ions are cold, it is shown that self-consistent debris charging with similar parameters hinders the formation of precursor solitons. This indicates that self-consistent debris charging is key to quantitative predictions of soliton formation. Additionally, when the ion and electron temperatures are comparable, as typical of conditions in low Earth orbit, Landau damping physics also hinders the formation of ion-acoustic precursor solitons. These results suggest that it will be challenging to exploit ion-acoustic precursor solitons for orbital debris detection in low Earth orbit.