The European Galileo, more effective than the American GPS?

Less known than the American GPS, Galileo, the European satellite navigation system, has been delivering operational services since 2016 and is now widely used by smartphones, vehicles, drones, and all kinds of consumer applications. This is no coincidence.


Even while the satellite constellation was still incomplete, the European system's performance quickly proved excellent, offering meter (three feet) accuracy, twice as good as GPS. To take advantage of this new performance, navigation chips naturally evolved over a few years to incorporate the new Galileo signals, thereby improving the availability and accuracy of positioning for users.

27 satellites at more than 12,400 miles altitude

Galileo, of course, is a satellite constellation. It is organized on three orbital planes at an altitude of 14,200 miles (23,200 km), each plane containing 8 nominal satellites and one or more redundant satellites. These redundant satellites are active and ready to be moved into orbit to replace any failed satellites. In total, the constellation thus contains 24 nominal satellites and at least 3 redundant ones. We are almost there! After the 13^th launch, which will take place in September 2024, the challenge will have been met, and the constellation will reach 27 satellites.


No matter how efficient they are, Galileo satellites alone cannot provide the services. They need navigation data calculated and transmitted by the ground segment, which plays a crucial role. The ground segment comprises transmission and reception stations deployed across fifteen European sites worldwide, particularly on French and Dutch overseas territories, and various centers in several European countries.

The main ground-based processes involve determining the precise orbits of the satellites in real-time within 8 inches (20 cm) and resynchronizing the atomic clocks of each satellite to the nanosecond (one billionth of a second), then transmitting this valuable data to the satellites so they can relay it to users in navigation signals.

Unmatched accuracy

It is worth noting that the four navigation constellations, Galileo, GPS (Global Positioning System, the American system), Beidou (the Chinese system), and Glonass (the Russian system) are interoperable: their signals are combined in the navigation chip to produce a single position.

It is also important to remember that this calculation is performed locally and autonomously by the chip without exchanging information with the satellite. The signals are, in fact, simply broadcast by the satellites to their billions of users, just like an FM radio transmitter broadcasts signals without knowing the listeners who are tuning in.


If Galileo is so precise, it is because the European engineers who designed it in the early 2000s knew how to observe and analyze the GPS system's operation at that time. However, competing with GPS in terms of accuracy is not the fundamental reason for the European system's existence.

Galileo, a significant space infrastructure, was desired 20 years ago by the member states of the European Union to meet their sovereignty requirements. It aimed to cater to the daily needs of 450 million citizens and over 20 million businesses while providing governments and their military forces with protected and robust services, completely independent of the American military GPS system and the Chinese and Russian systems.

A navigation system with numerous services

Galileo is a civilian system designed from its inception to provide the best services to citizens for free. The first of these, the positioning service, therefore delivers high-quality performance worldwide. Additionally, since January 2023, Galileo also transmits a high-precision positioning service aimed at professionals, the High Accuracy Service. This service offers 8-inch (20 cm) accuracy, for example, in agriculture or construction.

Galileo also provides two authentication services to combat spoofing, which is the transmission of false satellite signals to deceive the user about their position. The first, OSNMA (Open Service Navigation Message Authentication), aimed at consumer applications, is currently being tested, and the Signal Authentication Service, a more robust second service, will allow very demanding professional uses starting in 2026.


This ability to authenticate satellites protects the user against malicious threats. It also helps combat fraud when location is essential to control activities like fishing or transportation. The first regulatory use of Galileo authentication will confirm positions calculated in tachographs, the devices recording the position and speed of trucks.

Protection, assistance, and alerts

Protection and assistance to people are also significantly prioritized services. Each satellite indeed carries specific equipment that relays signals emitted by distress beacons when they are activated in the event of an air crash, shipwreck, or personal accident in remote areas.

This capability of worldwide and instant distress signal retransmission by the Galileo constellation has revolutionized the speed of position calculation for beacons, allowing near-instantaneous localization of distress, whereas it used to take several hours to locate them. Galileo can also confirm to beacons that the distress message has been received. This return channel to the beacons will soon allow rescue teams to communicate with people in distress to optimize rescue operations.


To complete the range of services provided to citizens, another innovation worth mentioning is the emergency alert system, which will be accessible to civil protection authorities of EU member states. Upon their request, Galileo can transmit emergency messages directly to smartphones and public display boards within its navigation signal.

Targeted at areas in emergency situations such as wildfires, floods, or industrial accidents, these messages will contain information and recommendations for affected populations. The service will have the crucial advantage of operating everywhere, even in the absence of a telephone network. Currently being demonstrated within the constellation, this service is expected to become operational by the end of 2025.

Towards a second generation of satellites

This long list of services may seem surprising in its diversity, but the story is just beginning. What will the new Galileo services look like in 2050? It's hard to predict, yet it is already necessary to build 2^nd generation satellites that will soon take over from the first satellites launched thirteen years ago.

Twelve satellites are thus under construction. They will be more flexible. When the first of them are in orbit in 2027, they will initially be programmed to transmit current signals to ensure service continuity. Then, in 7 to 10 years, once a sufficient number are deployed, they will also transmit new signals to meet Europe's future needs.

This article was co-written by Jean Maréchal and Damien Bellier, Interministerial Coordinator Delegate for Galileo.