PARIS — Deployment of Europe’s Galileo satellite navigation system has slipped again, with the European version of Russia’s Soyuz rocket now scheduled to carry four Galileo in-orbit validation satellites into orbit in two launches scheduled for late 2010 and early 2011, European Space Agency (ESA) Director-General Jean-Jacques Dordain said Oct. 9.

Both launches, from Europe’s Guiana Space Center in French Guiana, had been scheduled for 2010, but have suffered delays following last-minute difficulties with the satellites, which are being built by a European consortium led by Astrium Satellites and Thales Alenia Space.

Introduction of Russia’s Soyuz rocket at the French Guiana site has also been delayed repeatedly, with an inaugural launch now tentatively set for April 2010.

Dordain conceded that the new launch dates represent another delay but said he has written assurances by the chief executives of the two principal contractors that the satellites will meet the new schedule — November 2010 for the first launch, and early 2011 for the second.

The 27-nation European Union’s executive commission is financing the 30-satellite Galileo program and expects, with ESA assistance, to select a builder for the remaining satellites late this year. The 11 companies bidding for one or more of the six Galileo work packages are expected to submit final bids by Nov. 11.

Peter B. de Selding was the Paris bureau chief for SpaceNews.