Another attempt will be made on Friday to launch the first satellites for Galileo – Europe’s version of GPS.The two spacecraft are set to ride into orbit atop a Russian Soyuz rocket from Sinnamary in French Guiana.They should have left Earth on Thursday but the launch countdown was halted when a valve on pipes feeding propellant to the Soyuz’ third stage was found to be leaking.
http://www.bbc.co.uk/news/science-environment-15372540