European satellite navigation - a challenge

Satellite positioning has already become a standard procedure of navigating. However, today satellite navigation users in Europe have to rely on the US GPS or the (currently incomplete) Russian GLONASS. Yet the military operators of both systems give no guarantee to maintain an uninterrupted service. The US, for example, reserve the right to limit the signal strength or accuracy of the system (remember the times of selective availability!), or to shut down public access to the signal (which fortunately did not occur so far). In addition, China has indicated to expand its regional Beidou navigation system into a global system, the regional Indian IRNSS is in its developmental phase and is scheduled to be operational around 2011. In the light of these developments and recognising the strategic importance of satellite navigation and its potential applications, Europe figured out the need to get an independent global satellite navigation system already in the early 1990s. Thus, Europe decided to develop its own GNSS capability in a two-step approach: The first step is EGNOS which improves significantly the accuracy of positioning based on the two existing navigation satellite constellations GPS and GLONASS. Moreover, EGNOS offers integrity information. The second step is the development of Galileo as a global, independent, and interoperable satellite-based navigation system. Galileo will be the first global satellite-based navigation system under civil control.