Europe's first two fully operational Galileo satellites were successfully launched October 20 2011 from the European spaceport in French Guiana, South America.

The satellite payloads were built in the UK by Astrium and will test the system's communication networks before becoming part of the final Galileo system.

Minister for Universities and Science David Willetts said: "Today's launch marks an important milestone for the Galileo programme.

It is testament to the continued success of the UK space industry, which has played such a decisive role in constructing the Galileo system and these first satellites."

The technologies that the constellation will use have already been demonstrated with two British-built test satellites called GIOVE-A and -B, launched in 2005 and 2008, respectively. GIOVE-A has remained operational long after its expected lifespan and GIOVE-B contains the most reliable timing device ever launched into space.

A joint initiative of the European Commission (EC) and the European Space Agency (ESA), Galileo is the European Union's answer to the American global satellite navigation system GPS.

It is designed to provide a highly accurate global positioning system under civilian control with worldwide coverage and is one of the biggest space projects ever initiated in Europe.

The UK has made a considerable investment in the project and is involved at every level in developing this next generation of satellite navigation technologies.

Ann Sta, Director of Growth, Applications and EU Programmes for the UK Space Agency said: "It's great to see this launch of the first Galileo satellites. Industry can now see that the programme is credible and investment in downstream applications and new technologies will follow. Today marks a huge step forward for the programme."

Further Galileo satellites will be launched next year until 18 are in orbit and Initial Operational Capability (IOC) is reached around 2015.

At this point, the European Commission estimates that initial Galileo services will be certified as ready for use.UK companies have played a key role in building the Galileo system. Surrey Satellite Technology Ltd and German company OHB System won a contract valued at 566m euro to build 14 Galileo satellites.

Astrium and Logica have secured major Galileo contracts for the ground control segment and the ground mission segment respectively and a wide variety of other UK space firms are providing support to the programme.

At the heart of each Galileo satellite are the atomic clocks which will allow people using receivers, for example, built into smart phones, to know their position to within a metre.

These ultra-precise clocks will all beat in rhythm, rigorously synchronized with the ground network of control stations. That is why Galileo has been described as "one vast space clock".

Galileo will offer a number of services from 2015 onwards including an open signal, a search and rescue service, a public regulated service for Government approved users and also a prototype commercial service.

The European Commission (EC) estimates that 6-7% of European GDP - around 800 billion euro by value - is already dependent on satellite navigation currently provided by US GPS or Russian Glonass satellites.

The Government is supporting the industry's ambitious goals for growth in the UK space sector - growing revenues from Pounds 7.5bn to Pounds 40bn by 2030 and creating 100,000 high-value jobs in the sector.

Much of this growth will come from applications based on space services such as Galileo. The Government wants to see Galileo services start as quickly as possible to stimulate the development of new technologies and space-based solutions.