Galileo, navigačný systém

Galileo will be Europe’s own global navigation satellite system, providing a highly accurate, guaranteed global positioning service under civilian control. It will be inter-operable with GPS and GLONASS, the two other global satellite navigation systems.

A user will be able to take a position with the same receiver from any of the satellites in any combination. By offering dual frequencies as standard, however, Galileo will deliver real-time positioning accuracy down to the metre range, which is unprecedented for a publicly available system.

It will guarantee availability of the service under all but the most extreme circumstances and will inform users within seconds of a failure of any satellite. This will make it suitable for applications where safety is crucial, such as running trains, guiding cars and landing aircraft.

The first experimental satellite, GIOVE-A, was launched on 28 December 2005. The objective of this satellite is to characterize the critical technologies, which have already been developed under ESA contracts.

Two further experimental satellites are planned: GIOVE-B, scheduled for launch end of 2007 and GIOVE-A2, to be ready for launch in the second half of 2008. The actual launch date of this satellite will be decided later, taking into account the situation of GIOVE-A and GIOVE-B.

Thereafter, four operational satellites - the basic minimum for satellite navigation in principle - will be launched by end 2008 / 2009 to validate the Galileo concept with both segments: space and related ground infrastructure . Once this In-Orbit Validation (IOV) phase has been completed, the remaining satellites will be installed to reach the Full Operational Capability (FOC).

The fully deployed Galileo system consists of 30 satellites (27 operational + 3 active spares), positioned in three circular Medium Earth Orbit (MEO) planes at 23 222 km altitude above the Earth, and at an inclination of the orbital planes of 56 degrees with reference to the equatorial plane.

Once this is achieved, the Galileo navigation signals will provide good coverage even at latitudes up to 75 degrees north, which corresponds to the North Cape, and beyond. The large number of satellites together with the optimisation of the constellation, and the availability of the three active spare satellites, will ensure that the loss of one satellite has no discernible effect on the user.