British space engineers have received signals from the pioneer spacecraft for Europe's satellite-navigation system.
Giove-A will demonstrate key technologies
Giove-A is communicating with its ground station, they say, and all systems are performing well.
The 600kg Galileo satellite was lifted into orbit on a Soyuz rocket from Baikonur, Kazakhstan, on Wednesday.
It paves the way for a network of 30 satellites that will give Europe its own version of the US Global Positioning System (GPS).
Giove-A was built by the small British company, Surrey Satellite Technology Ltd (SSTL), a spin-off from the University of Surrey.
Engineers are operating the spacecraft from SSTL's control room in Guildford, Surrey.
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Max Meerman, a principal engineer at SSTL, said on Wednesday that they had received signals from the spacecraft and all was going to plan.
"The second solar panel is deployed and the power system is operating nominally," SSTL said on its website.
Over the coming days, engineers will check out the satellite's payload, which is designed to test key technologies to be deployed by future Galileo satellites.
Giove-A's first task is to secure use of the frequencies allocated by the International Telecommunications Union (ITU) for the Galileo system.
Once the payload is activated, the Galileo signals broadcast by Giove-A will be analysed by ground stations to make sure they satisfy the criteria.
Giove-A will also test atomic clocks for the Galileo system, which is expected to be complete in 2010.
The 3.4bn-euro (£2.3bn; $4bn) project will give civilian users a satellite navigation and positioning service that is 10 times more accurate than the alternatives available today.
While public signals from GPS are already widely used by the likes of sailors, mountaineers and motorists, the US military reserves the right to limit its use or switch it off for security reasons.