Galileo and EGNOS
Europe's Galileo satellite navigation system – currently under construction – will provide high-quality positioning, navigation and timing services to users across the whole world.
A civil-controlled system offering guaranteed continuity of coverage, Galileo is the outcome of a partnership between ESA and the European Commission. The first four Galileo satellites are already in orbit, with many more set to follow.
These first four 'In-Orbit Validation' satellites – the minimum number to guarantee the provision of exact positioning and timing at test locations – form the foundations of Galileo, validating the overall Galileo design while also forming the operational nucleus of the full satellite constellation to come.
Galileo’s full operational constellation will consist of 24 operational satellites plus six spares circling Earth in three circular medium-Earth orbits, at an altitude of 23222 km. Galileo will be interoperable with the US GPS and Russian Glonass systems, offering enhanced combined performance.
Building on the success of EGNOS
The first pillar of Europe's navigation programme, the European Geostationary Navigation Overlay Service (EGNOS) – operational since 2009 – is an overlay system based on a network of ground stations and three geostationary satellites.
The stations gather data on the current accuracy of GPS signals and embed it in the EGNOS signal, which is uplinked to the satellites to be transmitted to users.
EGNOS serves to sharpen the accuracy of GPS signals across Europe and informing users about the current reliability level of the system.
Designed against global standards set by the International Civil Aviation Organisation (ICAO), EGNOS began offering its Open Service for non-safety-of-life uses in October 2009, with its Safety-of-Life Service becoming available for aircraft navigation (allowing vertical guidance for landing approaches) from March 2011.
Services on offer
Once Galileo becomes operational, a portfolio of navigation services will be offered by Galileo and EGNOS, based on varying user needs:
- Open Service The Galileo navigational signal will be accessible by the general public free of charge, providing improved global positioning.
- Public Regulated Service Two encrypted signals with controlled access for specific users such as governmental bodies.
- Search and Rescue Service Galileo will contribute to the international Cospas–Sarsat international system for search and rescue. A distress signal will be relayed to the Rescue Coordination Centre and Galileo will inform the user that their situation has been detected.
- Safety-of-Life Service Already available for aviation to the ICAO standard thanks to EGNOS. The system will be extended to augment Galileo as well, thus further improving service performance.
- Commercial Service Galileo will provide a signal for high data throughput and highly accurate authenticated data, particularly interesting for professional users.
Last update: 22 August 2014