Formation flight of satellites in the presence of atmospheric drag

Abstract

The subject of this paper is the investigation of the effects of aerodynamic forces on the formation flight of satellites and the assessment of using differential drag as a means for formation maintenance. In order to study spacecraft formation flight in low Earth orbits, it is essential to consider the effect of J2. Schweighart and Sedwick have presented a set of linearized differential equations of motion, an extension of the Clohessy-Wiltshire equations, which includes the J2 effects and are valid for circular orbits. In this paper, the Schweighart-Sedwick equations are modified to include the effects of atmospheric drag while maintaining their linearity and simplicity. These ideas are then extended to include reference orbits of small eccentricity. This results in a set of linear differential equations of motion which takes into account J2 and drag perturbations as well as the elliptic nature of the reference orbit. Numerical simulation results based on the model are presented which characterize the effects of drag on projected circular type formations in the context of two different formation flying missions. It is shown that it is feasible to use differential drag to maintain a projected circular formation through simple panel rotation schemes.