Satellite navigation
Long ago, people who sailed the sea found their way by studying the positions of the Sun, Moon and stars. Then, around 1300, the introduction of the compass made life a little easier for these navigators.
Today, space technology has made it impossible for anyone to get lost. Any person, car, ship or aircraft fitted with a satellite navigation system can pinpoint their position to within 15 to 20 metres.
Satellite navigation relies on the use of a receiver calculating its position with signals sent by at least four satellites.
The system we now use in everyday life was first developed for military reasons. Between 1960 and 1968, 23 navigation satellites were launched by the US military to assist the navigation of Polaris submarines.
These eventually grew into the Global Positioning System (GPS). A similar system, called Glonass, was introduced by the military in Russia. Both of these are now available for civilian as well as military use. This is why Europe wanted to have its own guaranteed system.
Europe has now introduced a system called EGNOS, which improves the accuracy of the GPS system. ESA and the European Community are also jointly developing Europe's own civilian (non-military) navigation system. Called Galileo, it will be the first completely civilian system for global navigation .
Last modified 05 October 2011
