Influence of periodic lift and drag on the orbit of rectangular parallelepiped satellites

The trajectory of satellites on Low Earth Orbits (LEO) is highly perturbed by the satellite–atmosphere interaction. The two components of this aerodynamic perturbation are lift and drag, which are a function of the satellite’s geometry, materials, atmospheric environment, and flow conditions. The knowledge of these data is helpful to improve the orbit estimation; nevertheless, in practice, it is difficult to know all of these values, due to restrictions of the manufacturer and/or operator, and because requires the acquisition of all the variables in real time. For those reasons, a traditional approach is to fix the ballistic coefficient along the orbit lifetime, without considering his changes due to the flow direction, resulting from winds, or the satellite attitude and rotational dynamics. The purpose of the present paper is to analyse the influence of periodic variations of lift and drag on the satellite’s orbital elements, due to the satellite’s rotation at a constant angular velocity. Three parallelepiped solids were selected to model the satellite geometry, which are similar to the CubeSats standards. The aerodynamic coefficients are modelled using the panel method on free molecular flow, changing as a function of the angle of attack and the roll angle. The effects of periodic variations in drag result in secular perturbations in the orbital semi-major axis and eccentricity, with large differences at the lowest angular velocity. Lift, applied orthogonal to the plane orbit, affects the inclination at lower angular velocities, because it keeps the magnitude and direction of this perturbation for a long time. The novelty of this paper is the modelling and quantification of the effects of periodic lift and drag on parallelepiped satellites in LEO.