The European Space Agency (ESA) sends four new Galileo navigation satellites into space on an Ariane 5 rocket this Tuesday. It will bring the total number of satellites in the European navigation system to 22. The target is 30 satellites. 
After the launch, it can take several months to finalize the configuration of the satellites. Presently, 14 out of 18 Galileo satellites in space are fully operational. 

Initial services, free to users worldwide, will be available only on smartphones and navigation units already fitted with Galileo-compatible microchips. The new system was originally designed to deliver more precise data for private and commercial users than the current US Global Positioning System (GPS) does. However, the second generation of GPS offers similar accuracy to Galileo. 

2016 - a year of records

A previous Ariane 5 delivered four satellites in November 2016 and broke two records at once. Ariane 5 is the ESA's workhorse. Never before has an Ariane 5 rocket delivered so many — and such heavy — satellites at once. As this is the 75th launch of an Ariane 5, this rocket type now surpasses the number of launches of its predecessor, Ariane 4. What is more, all of the Ariane 5's launches have been flawless.

High precision for private and commercial users

Officially Galileo started offering its services to customers at the end of 2016, even though the system is not yet able to cover the entire globe. To reach that target, the system needs at least 24 fully operational satellites. The next satellite launches are planned for July 2018 and for 2020.

Galileo is one of the prestige projects of the European Union. In contrast to the US GPS system, which is 20 years older, Galileo is civilian-controlled. Therefore, Galileo offers its private and commercial users the whole spectrum of precision navigation that is technically possible. 

Galileo offers a precision of up to 4m for its fully open service. Commercial users and official government services can even receive a precision of a few centimeters. This is important, for example, for fully or partially automated planes, cars or ships. By 2018 Galileo should be fully operational, with at least 24 satellites in place. That is the threshold the system must reach before it can deliver a complete service.

The high precision offered by Galileo was one of the reasons why the Pentagon rejected the system in the first place. There were fears that adversaries of NATO or of other allies could use it for military purposes. However, engineers have found a solution to that problem: should a serious crisis arise, the military can jam a certain part of the broadcasting spectrum. This would cut off civilian use, but still retain the functions that are reserved for allied military purposes. 

Galileo can do much more than simply provide signals for navigation. In combination with the search-and-rescue satellites of the COSPS-SARSAT system, it will be able to better locate ships or mountain climbers in distress. It is also possible for people at the search-and-rescue control centers to respond to people who send distress signals from their SOS beacons.

Not just a European system

Besides the ESA member states, numerous other countries are involved in Galileo in one way or another. Among them are India, Israel, Morocco, Saudi Arabia, South Korea and Ukraine.

Even though China is developing its own satellite navigation system, called Bei Dou, it has also contributed to Galileo by setting up a university training center. This focuses mainly on the development of new applications and gadgets so that businesses and people can make use of the new navigation possibilities.

Russia, which has its own navigation system called Glonass, is also indirectly involved: all of the first 14 Galileo satellites have been launched by Soyuz rockets.

Of course, when it comes to "competing" navigation systems, it is worth remembering that they complement each other. Depending on how they are built and what software designs they have, Earth-based navigation gadgets and applications can use signals from more than just one of the systems - which increases their overall precision.