Investigators have uncovered the problems behind the failure of atomic clocks onboard satellites belonging to the beleaguered Galileo satnav system, the European Commission said on Monday. For months, the European Space Agency -- which runs the programme -- has been investigating the reasons behind failing clocks onboard some of the 18 navigation satellites it has launched for Galileo, Europe's alternative to America's GPS system. Each Galileo satellite has four ultra-accurate atomic timekeepers, two that use rubidium and two hydrogen maser.