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Galileo, the world's first civil-owned and operated satnav system, is up and running after passing a series of tests to validate its orbit, the European Space Agency has confirmed.
The project, which is also called the European Global Navigation Satellite System, is Europe's answer to the satellite navigation systems developed and run by the US, Russia, China and Japan militaries. These systems provide a service for civilians, but can be switched off or made less precise when desired.
However Galileo, which will be entirely under civilian control, is already three times over its original budget of £2.5 billion and nine years behind schedule. Galileo was first announced in 1999 with a completion date of 2008. The projected total 20-year cost of Galileo is estimated to be €22.2 billion.
The first four Galileo satellites were launched in 2011 and 2012 and have been undergoing tests since March last year, when the first determination of a ground location took place at the ESA's technical centre in Noordwijk, Holland.
A minimum of four satellites is required to provide a navigation fix. The satellites launched so far form the beginning of what by 2017 will be a 30 satellite system. Each satellite has a planned lifetime of 12 years.
The validation tests involve the generation of navigation messages from the four satellites across different positions throughout Europe. Marco Falcone, Galileo system manager, said: “ESA and our industrial partners deployed teams in the field continuously for test operations. More than 10,000km were driven by test vehicles in the process of picking up signals, along with pedestrian and fixed receiver testing. Many terabytes of data were gathered in all.”
When fully operational, Galileo will be capable of locating any object on Earth to within a distance of a few centimetres. The ESA said that the in-orbit validation tests showed that Galileo's future level of performance when the entire system is deployed is achievable.
The tests showed that Galileo’s observed dual-frequency positioning accuracy is an average 8m horizontal and 9m vertical, 95% of the time. Its average timing accuracy is 10 billionths of a second. The ESA said the performance is set to “sharpen” as more satellites are launched and ground stations come on line.
Improved accuracy is not only achieved by more satellites. Satnav positioning works by receiving signals from the satellites above. The atomic clocks on board Galileo satellites are accurate to less than one nanosecond every 24 hours, enabling a higher degree of accuracy than other satellite navigation systems. The satellites also orbit at a higher altitude than existing systems, 23,222km, enabling a wider cone within which to receive a signal, improving your chances of getting a navigation fix.