Galileo
Galileo is the European equivalent of the US Based DoD Satellite Constellation.

Why Galileo was created
Since the first constellation of US Based Department Of Defense run satellites started orbiting the Earth in 1978, concerns have been raised on the control and operation of the satellites. Until 2000 Selective Availability was implemented which gave consumer grade GPS an accuracy of 100 meters (not the current 15 meters that we are accustomed to today). This was partially designed for the cold war, and also to stop America's enemies using their GPS system against them, but in 2000 President Clinton phased out Selective Availability. Concerns over Selective Availability are still on-going and although there are no plans to re-enforce it, other countries would prefer not to be held ransom to America, so Europe after detailed discussions with America decided to create it's own constellation of satellites. To start with Galileo was to be it's own set of GPS satellites operating on a different frequency, but since further talks continued, Galileo will not only operate as it's own standalone GPS System, but also augment the current US operated system that we are using today.

Europe's Galileo
The plan for Galileo is to have a constellation of satellites orbiting the earth by 2008 and will enable civilian navigation independent of the existing US DoD GPS and Russian GLONASS systems. Galileo is a joint effort from European member states and the core system will comprise of 30 satellites (27 operating and 3 spares) orbiting the Earth in medium orbit in three planes inclined at 56 degrees to the equator at 23616 km altitude. This will provide excellent global coverage. Two centre's will be setup in Europe to control satellite operations and manage the navigation system.

Excerpt from Galileo World Paper (ESA)
"Navigation satellites already guide ships, planes and spacecraft. They provide the surveying reference for roads, bridges and cities and the time reference for power and telecommunications networks. They help cars, buses, taxis and ambulances to find their way along roads and help walkers, climbers, pleasure boats and golf buggies to find their way off the road. Quite soon, mobile phones will be equipped with navigation receivers, opening the way for a wide range of new services.

The popularity of GPS, despite its origin as a military system, and the fragility of the Russian GLONASS System, currently comprising too few satellites to offer a reliable service, together underline the strategic importance of navigation satellites to modern society. Accordingly, the European Transport Council decided in June 1999 to engage in the GALILEO Definition Phase and to take a decision on the implementation of GALILEO by the end of 2000. The member states of ESA decided in parallel on the complementary GALILEOSAT Programme, which is to cover part of the definition studies and the development of the GALILEO space and related ground segments, including the in-orbit validation of GALILEO.

The GALILEO initiative comprises the independent global GALILEO satellite constellation and associated augmentations and systems and also the integration of the EGNOS service. This paper describes the main technical features of the GALILEO
space and related ground segments as they emerge from the current definition studies and also introduces the key technology developments that are sponsored by ESA."

More information available at the Galileo Website