Europe's space ambitions are scheduled to blast off today with the launch of the first two operational satellites of the Galileo project, the European global satellite navigation system.

These two IOV (In-Orbit Validation) satellites will open the way for the full deployment of the 30 satellites that will make up the entirety of the Galileo constellation, due to be completed in 2018-2019.

The satellites, named "Thijs" and "Natalia" after two children who won a drawing contest, were due to be sent into orbit on Thursday, but a technical hitch delayed plans by 24 hours.

The satellites will be taken into orbit by a Russian Soyuz rocket, blasting off from the European spaceport in Kourou, Guiana. The project, which aims to offer global positioning accuracy to within a metre, has however been plagued by problems. Technical delays and cost overruns have cast a shadow over Europe's flagship space programme.

Once the orbit validation phase is over, another 14 satellites will be launched as soon as they are ready for delivery. An invitation to tender to build the final 12 satellites is likely to be announced in the coming days.

On board one of the satellites to be launched on Friday is best atomic clock ever flown for navigation, accurate to one second in 2 million years. The launch at 12.30 Central European Time (11.30 BST) can be watched live at the European Space Agency website.