Galileo is the European Union’s global navigation satellite system (GNSS), representing Europe’s independent contribution to worldwide satellite navigation infrastructure alongside GPS (United States), GLONASS (Russia), and BeiDou (China). Developed by the European Space Agency (ESA) and operated by the European Union Agency for the Space Programme (EUSPA), Galileo provides highly accurate positioning, navigation, and timing services designed to meet civilian needs while ensuring European autonomy in critical positioning infrastructure.

The Galileo constellation comprises 30 planned satellites (24 operational plus 6 active spares) in three orbital planes at approximately 23,222 kilometers altitude, providing global coverage with multiple satellites visible from any location on Earth. Galileo satellites broadcast navigation signals on multiple frequencies: E1 (1575.42 MHz, compatible with GPS L1), E5a (1176.45 MHz), E5b (1207.14 MHz), and E6 (1278.75 MHz), enabling multi-frequency positioning that improves accuracy and provides ionospheric delay correction.

Galileo offers multiple service levels tailored to different user communities. The Open Service provides free positioning accuracy of better than one meter horizontally and is available worldwide without restrictions. The High Accuracy Service delivers centimeter-level precision through Precise Point Positioning corrections broadcast via the E6 signal. The Public Regulated Service offers encrypted, robust navigation for government-authorized users requiring enhanced security and anti-jamming capability. The Search and Rescue Service supports global distress beacon detection with return link messaging capability.

A distinguishing feature of Galileo is its emphasis on integrity, the system’s ability to provide timely warnings when positioning information should not be trusted. The Safety-of-Life Service, initially targeting aviation applications, provides integrity information enabling users to assess whether Galileo positioning meets safety requirements. This characteristic makes Galileo particularly valuable for safety-critical applications including autonomous vehicles, rail signaling, and aviation approaches where undetected positioning errors could create hazardous situations.