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The European satellite positioning system Galileo

Europe’s own satellite positioning system Galileo is based on radio signals sent by a network of satellites orbiting the Earth and a global signal tracking network. The system provides its users with accurate timing, positioning and velocity services.

Galileo is compatible with the United States’ GPS, Russia’s GLONASS, and the Chinese BeiDou system. Unlike other positioning systems, Galileo is civilian-oriented, although military use has also been taken into account.

The development of the European Galileo programme began in 2003. The system is funded and owned by the European Union, but the European Space Agency, ESA, has been heavily involved in its development as well. Years 2007-2021, all operations related to Galileo was run by the European Commission's GSA (European Global Navigation Satellite System Agency), which was originally founded in 2004 to handle all EU programmes related to satellite navigation. From 2021 onwards, this role has been assumed by the successor of GSA, EUSPA (European Union Agency for the Space Programme).

Many fields depend on Galileo

The services of Galileo’s first phase became operational at the end of 2016 and the system is planned to be fully operational in 2020. The development costs of Galileo have been estimated to climb up to 10 billion euros in total.

In addition, maintaining the system is estimated to cost EU member states around 750 million euros each year. On the other hand, it has also been estimated that 6–7 percent of the EU’s gross domestic product as a whole is completely dependent on satellite navigation. This includes many fields for which satellite navigation is absolutely critical; for example, the energy, telecommunication and finance industries depend on it, since many of their services need exact and reliable data on time. Considering this, the development and maintenance costs of Galileo are a bargain when compared to the benefits it brings to the table.

Galileo ensures Europe's overall independence of other satellite navigation systems and improves Europe’s operational security. The Galileo system is developed by the EU, but China, Switzerland, Norway, Morocco, Ukraine and Israel – among others – have also participated, both financially and technically, in the development efforts. Galileo is, after all, a globally functioning system that users all around the world can use to their benefit.

Children from member states named the satellites

In 2020, the Galileo constellation will include 30 satellites. Six of them serve as reserve satellites, and the remaining 24 form the main constellation. The satellites orbit Earth at an altitude of 23,220 kilometres on three different orbital planes, which means it takes the satellites about 14 hours to go around the Earth. The GPS satellites orbit the Earth in 12 hours at an orbital altitude of 20,200 kilometres.

Like the GPS, the Galileo system includes a ground segment: the Galileo Control Segment, the Galileo Mission Segment, and multiple tracking and telemetry stations. Galileo satellites were named after the winners of a drawing competition that was organised for children from EU member states. The Finnish Anna satellite was launched in July 2018.

Four services provided by Galileo

Galileo is primarily intended for civilian use, which is why enabling market and user research was taken into account during its designing process. Galileo’s selection of services can be considered the system’s third segment together with the Galileo Space Segment (the satellite network) and the Galileo Ground Segment (tracking and control stations).

Open Service – OS

The Galileo Open Service is similar to the GPS’s positioning service aimed at civilian use: its positioning and timing services are free-of-charge and completely open access. Galileo OS has a location accuracy of a few meters, which is close to the accuracy of the civilian GPS.

The joint use of GPS and Galileo improves both location accuracy and availability of the timing and positioning services. The major part of Galileo-ready receivers specifically run Open Services.

The OS signal is transmitted in two frequency bands, E1 and E5, which improves the signal structure. This enables dual frequency reception and enhances robustness against jamming, which leads to superior performance when compared to the GPS.

The Galileo programme includes navigation message authentication for the Open Service (OS-NMA), which will allow users to be certain that the navigation signal they receive from the OS really originates from the Galileo satellites. Other GNSSs do not include an authentication function that would be available to all users, so Galileo’s NMA really sets it apart from the other systems with its robustness.

Public Regulated Service – PRS

The Public Regulated Service, PRS, can be compared to the GPS’s military signal. Using the service requires authorisation and the signals are heavily encrypted. The PRS is primarily intended for government use, e.g. for emergency services and the police, but it is also used by services critical to society, such as services related to the distribution of electricity or bank traffic.

Each member state has its own Competent PRS Authority (CPA), which controls the authorisations. Finland’s CPA is Traficom’s National Cyber Security Centre Finland. The CPA is also responsible for the administration of encryption keys. PRS signals are broadcast on frequencies E1 and E6. The signals are more resistant to intentional jamming or even spoofing, i.e. transmitting a counterfeit signal to provide erroneous information to receivers.

Commercial Service – CS

Galileo’s Commercial Service offers correction and integrity data that enable a higher accuracy than the Open Service provides. The CS’s location accuracy is in tens of centimetres. A commercial authentication service will also be available for the users of CS. This service will be not be provided for free, but it is still unclear how and from whom payment will be collected. CS signals are broadcast on frequencies E1, E5 and E6.

Search and Rescue Service– SAR

To enable the SAR service, Galileo’s satellites were built to be capable of receiving emergency signals from users and to forward the emergency signals to national rescue centres. With the emergency signal, the satellites can locate the users even when the users themselves are unable to provide a location. In addition, the satellites can transmit information back to the users in distress. The SAR service is part of the international COSPAS-SARSAT initiative and its Medium Earth Orbit Search and Rescue (MEOSAR) system.

More information

Miettinen, Seija; Öörni, Seppo; Lehtilä, Olli (2017). Satelliittinavigointijärjestelmien tehokas hyödyntäminen Suomessa. Toimenpideohjelma 2017–2020, Liikenne- ja viestintäministeriön julkaisuja 14/2017, 18.12.2017

Kari-Pekka Karlsson (2018). Paikkatietopoliittinen selonteko, Maa- ja metsätalousministeriön julkaisuja 4a/2018, toukokuu 2018

Antti Rainio (2014). Uudistuva satelliittinavigointi, PRS-signaalin hyödyntäminen, Liikenne- ja viestintäministeriön julkaisuja 11/2014, 2.4.2014

European GNSS Agency, Galileo is the European satellite-based navigation system

European GNSS Agency, GNSS Market Report

European GNSS Agency, The European GNSS Service Center

European Space Agency, What is Galileo