After a long delay, the first two satellites of the Galileo constellation will be launched from French Guyana on October the 20th.
Those satellites, and the other two that will be launched in January 2012, will be used for the In Orbit Validation - IOV phase of the Galileo Project. "This quartet of satellites, built by a consortium led by EADS Astrium Germany, will form the operational nucleus of the full Galileo satnav constellation. They combine the best atomic clock ever flown for navigation – accurate to one second in three million years – with a powerful transmitter to broadcast precise navigation signals." ESA says.
The launch will use a Soyuz launcher.
For this historic moment, ESA set up a dedicated website with all the information available.
IOV dispenser (photo from ESA website).