Multi-criteria design of continuous global coverage Walker and Street-of-Coverage constellations through property assessment

No general rules exist for constellation design; instead, constellation designers have to consider various cost drivers in a trade-off way. This paper presents a systematic method for the design of continuous global coverage Walker and Street-of-Coverage constellations, by taking seven critical constellation properties (coverage, robustness, self-induced collision avoidance, launch, build-up, station-keeping, and end-of-life disposal) as design criteria. In this method, a set of characteristic parameters, which can determine the constellation configuration, are first identified based on the review of Walker and Street-of-Coverage constellations. Then a series of indexes are proposed and modelled as functions of the characteristic parameters, to quantitatively assess the constellation properties. Through the quantitative assessment, the influence of constellation configuration on constellation properties are revealed, and the trade-offs between constellation properties are analysed. Finally, taking the characteristic parameters and constellation properties as the design variables and objectives, a multi-objective optimisation problem is formulated to find the globally optimal constellations for given missions.