Synchronizing Galileo's satellites with an ensemble of high-performance atomic clocks

Europe's Galileo is the world's most precise satellite navigation system, providing meter-level accuracy and very precise timing to its four billion users. An essential ingredient to ensure this stays the case are the atomic clocks aboard each satellite, delivering pinpoint timekeeping that is maintained to a few billionths of a second. These clocks are called atomic because their "ticks" come from ultra-rapid, ultra-stable oscillation of atoms between different energy states. Sustaining this pe...