Development of new GNSS based Precise Orbit Determination (POD) concepts for satellite missions (including satellite Formation Flying and satellite Constellations ) into LEO, GTO, MEO, GEO and HEO taking full advantage of the extension of GNSS signal availability for the before mentioned orbit types.

Currently two Global Navigation Satellite Systems (GNSS) are fully operational. These two systems are the US GPS and the Russian GLONASS. However, the number of available GNSS in 2020 will grow up to four operational systems and the number of available GNSS satellites will be over 120 for potential users. Each GNSS will have at least three civil frequencies and more than two types of new GNSS signals. The complexity for processing of GNSS signals will increase substantially and the aspect of Interoperability will gain on importance for all GNSS users. At the time being, the operational and those systems that are currently under development supporting the use of GNSS for Low Earth Orbits (LEO) only. However, in 2012, the US decided to extend the GPS support for space users from LEO only to space missions into GTO, MEO, GEO and HEOs. For this reason, the US introduced for their GPS III next generation satellites a set of requirements to support the so called GNSS Space Volume Service extension. Due to the fact that such a space service volume extension is quite difficult to achieve for only one system stand alone, the US started to lobbing within the activities of the International Committee on GNSS (ICG) all other GNSS service providers to take up also requirements in order to support the GNSS Space Service Volume extension in their next generation of satellites. In 2014, all GNSS service providers confirmed their commitment to support this initiative in general. The GNSS Space Service Volume extension will change the entire approach for POD concepts related to LEO, MEO, GTO, GEO and HEO satellite missions. The amount of GNSS observations that can be used for POD will increase by a factor of around 15 per epoch per tracked satellite. This activity will build on a precursor study and shall cover the following tasks: - Development of new GNSS based POD concepts (single satellite, satellite Formation Flying and also satellite Constellations) for missions into LEO, GTO, MEO, GEO and also HEOs - Optimal use of multi-frequency, multi-signal and also multi-GNSS constellation observation processing for advanced POD concepts, improving accuracy and robustness of solutions - Detailed analysis of Real-Time POD versus Batch POD concepts - Detailed analysis of pure Kinematic versus Dynamic POD concepts - Development of concepts - Identification of potential demonstration experiments and missions - Identification of drivers and also requirements for future GNSS equipment related to an improved POD capability - Identification of requirements for Ground to Space and Space to Ground communication related to advanced POD capability for missions into LEO, GTO, MEO, GEO and also HEOs - Identification of drivers and requirements for new POD concepts (single satellite, satellite Formation Flying and also satellite Constellations), based on GNSS and also other observations suitable for POD (e.g. ISL, Laser Ranging etc.) for missions into LEO, GTO, MEO, GEO and also HEOs - Identification of requirements for future ops concepts resulting from advanced POD concepts for missions into LEO, GTO, MEO, GEO and also HEOs