Information content analysis of shadow imaging of GEO satellites

Space situational awareness (SSA) is important for understanding the space environment to ensure safe operation of space missions. SSA activities include detecting, identifying, tracking, and characterizing artificial satellites and orbital debris. SSA objectives rely on the information that can be gained from ground-based and space-based sensors, such as optical telescopes and radar. For space objects at geosynchronous altitudes, obtaining resolved imagery from Earth is not feasible with practical instruments. Shadow imaging, however, offers the possibility of obtaining a high-resolution silhouette of the object from the shadow cast when it passes between the observer and a stellar source. Prior analyses have concluded that such a method is feasible. Herein, we discuss the usage of information-theoretic methods to understand the limitations of stellar shadow imaging. Scene-based information applied to the irradiance pattern treated as an image is investigated, as well as task-based information that links knife-edge localization, a surrogate for system resolution, to Shannon information.