Precise Maintenance of a Mid Inclination Repeat Groundtrack Trajectory with Low Thrust Small Satellite

Abstract

Operating in a frozen orbit is essential for remote sensing applications such as Interferometric Synthetic Aperture Radar (InSAR) that require perfectly repeating satellite imaging geometries. These orbits trace out the same set of groundtracks in the presence of conservative forces only, thus resulting in Repeat Groundtrack Trajectories (RGT). To operate within the target frozen orbit, spacecraft have to acquire and maintain this RGT with regular control maneuvers to counteract nonconservative perturbations. This problem is complicated by low-thrust propulsive maneuvers that supply a small fraction of the delta-v available to other InSAR missions. We at Capella Space have developed a novel low-thrust, autonomous in-plane only maneuver planning strategy for smallsats that has been validated in parallel with demanding commercial tasking as well as intense solar weather. This paper details the design and implementation of the ground-based planning architecture, along with the unique challenges overcome during development. Limited data from current operations is also presented. Results show that Capella Space is capable of maintaining our latest-generation satellites within a 250 meter tube about a mid-inclination Repeat Groundtrack Trajectory.