Galileo

European satellite system

The development of the European Galileo via the EU and the European Space Agency (ESA) started in the late 1990s and the system is in many ways more modern than GPS and GLONASS. The system is compatible with GPS and GLONASS and has been built up over several extended phases. The first satellites in the active constellation were launched in 2011 and in December 2016 a milestone called Initial Services was declared. This milestone meant that 18 satellites had been launched.

The total satellite constellation for Galileo will finally reach 30 satellites, distributed over three different orbital planes approximately 23,222 kilometres above the Earth's surface. The satellite orbits have an inclination of 56 degrees, which is slightly greater than the GPS satellites.

Satellite signals

The Galileo satellites transmit three signals, E1, E5 and E6, with E5 divided into E5a and E5b. In addition to pure navigation signals through the so-called Open Service (OS), the services

• High Accuracy Service (HAS), providing data for measurements with Precise Point Positioning (PPP)
• Search and Rescue Service (SAR), enabling communication during rescue missions
• Public Regulated Service (PRS)

are also provided.

The satellites are controlled and adjusted through around twenty control stations with slightly different functions, which have an uneven global coverage. Galileo uses the geodetic reference frame Galileo Terrestrial Reference Frame (GTRF) which is an independent realisation of the International Terrestrial Reference System (ITRS).

More information

• Official information about Galileo is reported at several websites:
  • European Space Agency (ESA) (new window).
  • European Commission (new window).
  • European Union Agency for the Space Programme (EUSPA) (new window).
  • European GNSS Service Centre (GSC – part of EUSPA) (new window).
• European GNSS Service Centre (GSC) (new window) reports current status of Galileo.