Europe's global satellite-navigation system, Galileo, comes a step nearer on Wednesday with the launch of its first demonstrator spacecraft.

Giove-A will be lofted into orbit by a Soyuz rocket from Baikonur, Kazakhstan.
The demonstrator, built in the UK by Surrey Satellite Technology Ltd, will test key components in the Galileo network, notably its atomic clocks.
It also has the job of securing the radio frequencies allocated to the project under international agreements.
This requires Giove-A to transmit a sat-nav signal of the correct structure from orbit within the next six months. The SSTL team hopes to do it within a matter of days.
The Galileo project is costing some 3.4bn euros (£2.3bn; $4bn) in public and private finance. It is the biggest space project ever undertaken in Europe, and will eventually comprise a constellation of 30 satellites.
The endeavour is being driven by the European Space Agency and the EU to give member states guaranteed access to a satellite-distributed precise timing and location service.
At the moment, they have to rely on the American Global Positioning System (GPS).
Lift-off from the Baikonur cosmodrome is scheduled to occur at 1119 local time (0519GMT).

Radiation lessons
Giove-A has been designed and built by SSTL in under three years, a remarkably short timeframe for what is essentially an experimental spacecraft.
"Three years ago I did a sketch of what I thought we could do," recalled John Paffett, projects director with SSTL.
"To go from that sketch to what we have now is amazing. It is a very good demonstration of the company's capability - short timeframe, rapid programmes," he told the BBC News website.
Giove's orbit will be novel, too - at least for Europe; it has never put a satellite 23,000km above the Earth.
It is a particularly high radiation environment and the spacecraft will carry two instruments to assess conditions.
"If you haven't got this environment characterised properly you cannot build the constellation satellites in the full knowledge that you have optimised their design," explained SSTL senior accounts manager, Phil Davies.
"You would either under-engineer, in which case the satellites would not last as long as they should do; or you would over-engineer, in which case you make the satellites heavier and more expensive than they need to be."

'Health' messages
The Giove-A mission will also run the rule over two onboard rubidium atomic clocks. These are the heart of any global positioning system, sending highly accurate timing signals back to Earth.
With the experience gained from Giove, Esa can start launching the fully fledged Galileo constellation into space.

Javier Benedicto (Esa)
Benedicto: Galileo will bring improved performance
The 30 satellites- 27 active spacecraft and three spares - will be put in three orbital planes straddling the globe.

"We are aiming to provide one-metre, worldwide accuracy through Galileo's 'open' service - this is not possible today without regional or local augmentation," said Esa's Galileo project manager, Javier Benedicto.
"With the use of three signals, we will have access to centimetre accuracies, and with these you will see many more services than you have to today; and European industry is working to develop those applications."
In contrast to GPS, Galileo services will come with guarantees, to give entrepreneurs confidence to build their businesses around sat-nav.
There will also be integrity, or system 'health', messages, which make Galileo suitable for safety-of-life applications where service failure or degradation could endanger lives.

Launch series
Galileo will be compatible and interoperable with GPS, which should dramatically improve the quality and reliability of the sat-nav experience for users.
Analysts expect there to be a boom in sat-nav markets as the functionality and internet-linked applications are incorporated into mobile phones.
"With this first satellite, we can say Galileo is on track," said Giuseppe Viriglio, Esa's director of European Union and industrial programmes.
"We will be able to test the most critical technologies that are required if we want to get the performance we are looking for. This satellite will also mark the first step in a long list of launches.
"In 2006, we will launch another test satellite - Giove-B; and we will have launches again in 2008, 2009 and 2010, ending with the full deployment of Galileo when we have 30 satellites in orbit."
source

Esa's website, for information on Galileo