The first two operational Galileo satellites were launched from Europe's Spaceport in French Guiana in October 2011. Once the In-Orbit Validation (IOV) phase has been completed, the remaining satellites will be placed in orbit at regular intervals to reach Full Operational Capability (FOC).
The complete Galileo constellation will comprise satellites spread evenly around three orbital planes inclined at an angle of 56 degrees to the equator. Each satellite will take about 14 hours to orbit the Earth. One satellite in each plane will be a spare, on stand-by should any operational satellite fail.
The Galileo IOV satellite
Mass about 700 kg
Size with solar wings stowed 3.02 x 1.58 x 1.59 m
Size with solar wings deployed 2.74 x 14.5 x 1.59 m
Design life more than 12 years
Available power 1420 W (sunlight) / 1355 W (eclipse)
Altitude 23 222 km
From most locations, six to eight satellites will always be visible, allowing positions and timing to be determined very accurately to within a few centimetres. Interoperability with the US system of GPS satellites will only increase the reliability of GALILEO services.
The pre-Galileo GIOVE (Galileo In-Orbit Validation Element) satellites
The GIOVEs were aimed at testing Galileo positioning system technologies in orbit.
GIOVE-A, was launched in December 2005, its primary goal being to claim the frequencies allocated to Galileo by the International Telecommunications Union (ITU). It has also been used to test the design of two on-board rubidium atomic clocks.
GIOVE-A was the first European satellite to be launched into medium Earth orbit (MEO). It carries two environmental monitors that have been in operation almost continuously since launch, gathering vital data about the Galileo intermediate circular orbit environment and helping in the design of the full constellation.
Launched in April 2008, GIOVE-B was the first satellite to actually transmit Galileo signals. After launch, early orbit operations and platform commissioning, GIOVE-B's navigation payload was switched on and signal transmission commenced.
Key facilities in the testing of GIOVE-B signals include the GIOVE-B Control Centre at Telespazio's facilities in Fucino, Italy, the Galileo Processing Centre at ESA's European Space Research and Technology Centre (ESTEC) in the Netherlands, the ESA ground station at Redu, Belgium, and the Rutherford Appleton Laboratory (RAL) Chilbolton Observatory in the United Kingdom.
GIOVE-A2 essentially extended the mission of its predecessor, GIOVE-A, securing the Galileo programme by maintaining the critical ITU frequency and facilitating the ongoing development of ground equipment.