Ionospheric plasma drag on small satellites in low-earth orbit

This study presents a novel investigation of charged aerodynamics for satellites with complex 3D geometries, non-uniform potential distributions and different grounding configurations in low Earth orbit (LEO). In LEO, the spacecraft surface potential is usually negative, enhancing the collection of positively charged particles and generating drag forces. The surface potential is influenced by solar array voltage, grounding type, and environmental charging. Unlike neutral drag, the satellite's shape, particularly its aspect ratio, has minimal impact on charged aerodynamics. Instead, charged drag strongly relates to the surface potential and grounding configuration, with this dependence intensifying at higher altitudes, primarily due to sheath expansion caused by lower plasma density. In this study, with spacecraft surfaces at −100V, the charged drag coefficient increases by a factor of up to 18.5 at an altitude of 400 km, whereas it increases by a factor of up to 37 at 700 km. The study shows that ionospheric charged drag becomes a non-negligible factor for small satellites (dimensions of order of 10 cm) with substantial negative charging. At altitudes above 600 km, highly negative surface potentials (below −30V) can cause charged drag to surpass neutral drag. At 400 km, the charged drag can exceed 10% of the neutral drag for potentials exceeding −20V and can surpass the solar radiation pressure for potentials more negative than −50V.