Effects of Charge Density Variations on Aerodynamics of Low Earth Orbit Objects

Predicting the ionospheric aerodynamic forces acting on a satellite in low Earth orbit (LEO) is critical both in terms of avoiding collisions with other satellites in this area as well as deorbiting the spacecraft according to the international guidelines. The LEO is an ensemble of charged and neutral ions and it has been shown that the momentum exchange between these particles and a charged body has a significant impact on the drag forces acting on the body, and in-turn on its motion. Given the substantial variations in densities and relative composition of charged species with altitude and latitude, the resultant drag force on the satellite spans a wide range. This paper presents a comprehensive study of drag forces resulting from the interaction of plasma in LEO and a floating object. The simulations are performed using pdFOAM, an electrostatic particle-in-cell code. We show that the different ion percentages play a critical role in the value of the drag coefficient. Moreover, cases with lower density and high percentage of H+, have the largest value of drag coefficient. The drag coefficient increases significantly with increasing altitude, i.e. for lower ion density.