Like the Global Positioning Satellite system, GPS for short, the Galileo satellite navigation system will be able to determine a receiver's position nearly anywhere in the world.
But unlike the US system that is operated by the military and designed to purposely distort a civilian user's exact position by 15 to 20 meters, the civilian-operated Galileo system will be accurate to within 4 meters.
The system is being developed by the European Union, European Space Agency and Galileo Industries.
The Galileo system will consist of 30 satellites positioned about 23,000km above the earth. The first satellite will be launched in late December, and the system is expected to be fully operational in late 2010.
The satellites will transmit radio signals to the ground. Any person with a Galileo-compatible receiver will be able to use the system.
Like GPS, receivers will be embedded in vehicles, ships, planes, trains and spacecraft, and used in hand-held portable devices.
The Galileo receiver interprets data from at least three satellites to determine its position.
Each satellite transmits time signals and information about its location in orbit. When the receiver on the ground picks up these signals, it logs the time the signals were sent and determines how long the signal took to reach it to determine its location on the ground - a process known as trilateration.
The receiver translates this information into latitude, longitude and elevation above sea level to determine its location.