The first two satellites for the European Galileo navigation system have been orbiting Earth since 21 October 2011. Now, two more are about to follow; on 12 October 2012 at 20:15 CEST, a Soyuz rocket will launch satellites three and four into their position in space.
The successful launch of the first two Galileo In-Orbit Validation (IOV) satellites on 21 October 2011 marks the start of space segment construction for an independent European satellite navigation system.
An equation with four unknowns – at least, that is how satellite navigation is summarised by Walter Päffgen, Managing Director of the German Aerospace Center's Space Applications Company and Head of the Galileo Control Centre.