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European GNSS

The Navigation Office provides support in the area of data processing and analysis, performance analysis. It performs operational orbit predictions for the International Satellite Laser Ranging Service (ILRS), operational precise/rapid orbit and clock determination, computation of antenna patterns, and provides support to Galileo Sensor Stations (GSS) site deployment and to Ranging and Integrity Monitoring Station (RIMS) deployment. It also provides consultancy on modelling and data processing, mission analysis for the constellation, orbit validation activities for orbits and clocks, ionosphere, group delays, and intersystem biases, and is involved in the generation of the Galileo Geodetic Reference Frame. Furthermore, the Office participated in European Commission studies for the Galileo Commercial Service.

Earth Observation Missions

A number of European and American missions have been equipped with radar altimeter instruments that observe the level of the sea surface from space. To do this, the height component of the satellite orbits needs to be determined with centimetre accuracy, matching the accuracy of the altimeter observations.  The Navigation Support Office provides support to Precise Orbit Determination (POD), evaluation, analysis and improvement of models and standards, as well as instrument calibration (radar altimeter and GNSS antenna).  Examples of missions already supported include ERS, Envisat, Cryosat, GOCE and also non-ESA missions JASON 1&2. Solutions with multiple simultaneous data types (GNSS, SLR, DORIS, altimetry, S-band range, Doppler, and angle tracking) are typically performed, allowing the alignment of different reference frames and estimation of inter-system and instrument biases. Based on all these capabilities, the Navigation Support Office is one of the leading institutions for Low Earth Orbiting (LEO) satellite POD activities and very well suited for supporting the upcoming European programme for Earth Observation, called Global Monitoring for Environment and Security (GMES) and its related Sentinel satellite missions.

Automated Transfer Vehicle (ATV)

The Automated Transfer Vehicle (ATV) is part of the European contribution to the International Space Station (ISS) program. The main tasks of the ATV are to provide logistics supply, station re-boost and ISS waste retrieval. The rendezvous of the ATV and ISS is based on a real-time onboard relative navigation concept, using GPS data from receivers of ISS and ATV. The Navigation Support Office conducts in this context simulations before the flight and also post facto performance analysis of the relative orbit determination accuracy in order to support the ATV missions.

Space Situation Awareness (SSA)

An important atmospheric application of GNSS data is the monitoring of ionospheric activity (total electron content or TEC). Dual-frequency GNSS signals enable direct measurement of this parameter, and by merging the data from hundreds of globally distributed GPS receivers, detailed maps of the TEC and its evolution as a function of time can be constructed. Such maps have been computed routinely for many years. Figure 1 shows an example. The importance of these products lies in the fact that high solar activity leads to high TEC values, which can seriously disturb satellite communications. The Navigation Support Office provides ionospheric TEC maps to the scientific community. Learn more