The Galileo satellite is to become on of the most accurate satellite navigation systems for Europe.
A total of 30 Galilelo satellites will be placed into orbit about 23,222km above Earth by 2020.
British companies have played a key part in the construction of these satellites and together with a German company won a contract for £450 million.
Other British companies, like Logica and Astrium have won contracts to provide segments to assist in the ground control and ground mission areas.
The atomic clocks on each of the Galileo satellites are accurate to within 0.9 billionths of a second in 24 hours.