Europe's quest to build its own version of GPS is about to take an important step forward with the launch of a test spacecraft, Giove-B.

- 26 / 04 / 2008 13:47

The demonstrator must prove the key technologies in the Galileo satellite navigation system before the full network begins its roll-out in 2010.

These include the atomic clocks which provide the precise timing that underpins all sat-nav applications.

The launch is a big moment for Galileo which has suffered severe delays.

Europe has already spent 1.6bn euros ($2.5bn) on the project and ministers have warned that the additional 3.4bn euros ($5.3bn) recently approved for sat-nav investments will be the limit on expenditure.

Giove-B will be lofted by a Soyuz-Fregat vehicle from the Baikonur spaceport in Kazakhstan. The rocket is timed to leave Earth at 0416 local time, Sunday (2216 GMT, Saturday).

Galileo is envisaged as being technologically complementary to GPS, and is touted as a key high-technology venture for the EU.

It is designed to improve substantially the availability and accuracy of timing signals delivered from space.

Users should get quicker, more reliable fixes and be able to locate their positions with an error of one metre compared with the current GPS error of several metres.

Giove-B will be the second demonstrator satellite to go into orbit following the launch of Giove-A in 2005. The first mission met international obligations to claim the frequencies Galileo will use to transmit its signals to receivers on the ground.

This second mission flies a spacecraft which is, to a large degree, a template for the 30 operational platforms that will follow.

"We're already cutting metal on the first four of those," said Richard Peckham, from EADS Astrium, which has led the development of the demonstrator.

"Giove-B is therefore a significant step in that direction. There are new technologies in Europe which haven't yet flown. This is the opportunity to test their performance in space," he told BBC News.

A fundamental focus for Giove-B will be the in-orbit behaviour of its passive hydrogen maser clock.

The hydrogen maser (silver box) is pictured during payload integration

bbc