Fast Approximate Method of Satellite Coverage Assessment With Temporal and Spatial Modifiers

As the cost of launch and spacecraft systems has lowered in recent years, there has been increased interest in the use of large satellite constellations to provide global high temporal frequency coverage. For Earth observation systems this has been accompanied by increased desire to provide high resolution imagery with resultantly smaller fields of view. Traditional coverage modelling methods, such as grid point approaches, become intractable for constellations of this type due to the computation required. This work presents an approximate method of coverage modelling that can rapidly produce average revisit time estimates even for large constellations and small fields of view using geometric approximations. The inclusion of modifiers to the baseline revisit time allows variations in coverage to be considered, such as in the case of repeating ground tracks. Comparison with grid-point coverage methods and historical collection patterns show agreement in mean revisit time, and indicate that localised maximum and minimum revisit times can be captured through the addition of modifiers. A variety of satellite systems are modelled, including the Planet Flock constellation, the ICEYE constellation, the Starlink constellation and a combined 340 spacecraft representing all EO spacecraft in operation at time of writing. These results demonstrate that the presented method has the potential to provide an efficient means of analysing difficult to model systems, such as mega-constellations and those with small sensor fields of view, with modifiers offering an efficient way to calculate additional coverage parameters