What is Galileo?
Galileo is the European Union's Global Navigation Satellite System (GNSS), providing accurate, reliable positioning data for civilian users under full European civil control — unlike GPS (US military controlled), GLONASS (Russian), or BeiDou (Chinese). The full Initial Operational Capability (IOC) was declared in 2016 with 18 satellites; Full Operational Capability (FOC) with 30+ satellites was reached progressively through 2022–2024.
Constellation and technical specifications
Galileo operates 30 satellites (24 active + 6 spare) in three Medium Earth Orbit planes at 23,222 km altitude, with an inclination of 56°. Each satellite carries extremely precise passive hydrogen maser atomic clocks (accurate to 1 nanosecond per day) plus cesium clocks as backup. Orbital period is approximately 14.07 hours, chosen so that satellite ground tracks repeat on a 10-day cycle. The constellation provides global coverage including high latitudes (up to 75°N) with at least 4 satellites visible at any point.
Services and accuracy
Open Service (OS): Free public service providing positioning with 1–3 m horizontal accuracy using L1+E5a dual-frequency receivers. High Accuracy Service (HAS): Launched 2023, provides corrections broadcast via satellite enabling 20 cm horizontal and 40 cm vertical accuracy without ground reference stations — the world's first free high-accuracy GNSS service. Public Regulated Service (PRS): Encrypted service for government and security users, resistant to spoofing and jamming. Search and Rescue Service (SAR/Galileo): Hosts COSPAS-SARSAT SAR transponders on all Galileo satellites and uniquely provides a return link to confirm beacon receipt.