Constellation Options for Future Civil GNSS

Giorgio Solari and Pedro Pablos

Abstract:	If the civil navigation user communities wanted a future GNSS tailored to their specific requirements, compatible with GPS and GLONASS, with improved performance, and controlled by international civil authorities, then the development and deployment of a non-GE0 constellation of dedicated low-cost spacecraft would likely become a necessity. Even exploiting potential flight opportunities in suitable orbits would only guarantee a partial fulfillment of the civil user requirements, and a dedicated complimentary constellation would still be needed. The present paper intends to give indications on potential dedicated constellations for the future GNSS, with comparative performance analyses and preliminary system feasibility considerations for the most promising options. A global GSO constellation consisting of GE0 and dedicated circular IGSO (Inclined GeoSynchronous Orbit) civil navigation payloads is presented here. This constellation consists of GSO ‘space-modules’, constituted by a limited subset of few GE0 and IGSO satellites and their corresponding Ground Segment. Each GSO ‘space- module’ could be designed to be compatible with GPS and GLONASS in order to work as an important augmentation and allowing early autonomous civil control over its rel- evant coverage region. A stepwise deployment would be feasible, enabling the setup of an international, worldwide civil controlled system with a rapid development for those regions that need an earlier civil service and can afford the necessary initial investment. This modularity feature is absolutely unique in comparison with other alternatives, together with the fact of achieving better geometrical performance (and therefore better navigation accuracy and availability) with less dedicated satellites and a more favourable spare configuration. Civil IGSO satellites could represent a suitable ‘dedicated complement’ even if secondary navigation payloads are embarked on board any potential host platform, as the ones offered by INMARSAT GE0 and ICO or ESA ARCHIMEDES missions. In any case, options for dedicated civil navigation spacecraft constellations must envisage all potential sets of orbits which range from ICO to GSO altitude. Only further detailed cost/benefit analyses can provide the criteria to select the most effective candidate.
Published in:	Proceedings of the 1995 National Technical Meeting of The Institute of Navigation January 18 - 20, 1995 Disneyland Hotel Anaheim, CA
Pages:	71 - 78
Cite this article:	Solari, Giorgio, Pablos, Pedro, "Constellation Options for Future Civil GNSS," Proceedings of the 1995 National Technical Meeting of The Institute of Navigation, Anaheim, CA, January 1995, pp. 71-78.
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