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Galileo system: overview of european GNSS

Satellite in space


Galileo system has been mentioned a lot lately. Galileo is a global navigation satellite system (NGSS), currently being created and developed by the European Union. Now that another test of the Galileo system has been conducted (with promising results, indeed), media reports are focusing even more on this topic. Despite his success and promising future, though, not many people know much about this Europe’s satellite system. Proof is, it is often referred to as the “Galileo GPS”, which is actually incorrect. Even though astronomy is not among the topics we plan to include on our website, technology is. And with all this fuzz about Galileo, we decided to write an article on the subject. This article’s aim is to somehow illustrate the project and, at the same time, clarify some aspects about the Galileo system.

Why isn’t the expression “Galileo GPS” correct?

The GPS system‘s project was launched in 1973 in the United States, with its aim being to overcome the limitations of existing navigation systems. GPS stands for Global Positioning System and is, just like the Galileo system, a GNSS.For this reason, Galileo and GPS both stay at the same “hierarchical level”: they are both GNSS although being different systems.

What the Galileo system is and how it works

Galileo satellite navigation system (source: ESA)

Galileo satellite navigation system (source: ESA)

Galileo system is, as mentioned above, Europe’s own satellite system. As you may have guesses, it was named after Italian astronomer Galileo Galilei, considered to be a pioneer in celestial exploration. It is a guaranteed GNSS able to provide high accuracy and (this is pretty awesome) it can work together with GPS and Glonass (with the latter being Russia’s GNSS). Its main advancement with respect to the currently available system will be accuracy: claimed to be in the meter-range, it is far less than the one we are used to. Also, while the above-mentioned systems are military-run, Galileo is civil-controlled: one of the implications is that there is no reason to impose availability restrictions due to strategic reasons.

At a glance

Some of the data that can be found on the ESA’s website are:

Size 2.74 x 14.5 x 1.59 m (satellites 1-4) – 2.5 x 14.67 x 1.1 m (satellites 5-26)
Weight 700 kg (satellites 1-4) – 732.8 kg (satellites 5-26)
Available power 1420 W (satellites 1-4) – 1900 W (satellites 5-26)
Operational lifetime 12+ years

The first test satellite was launched in 2005, while the first one to be part of the operational Galileo system was launched in 2011. At the time of writing there are 18 active satellites orbiting at an altitude of 23 222 km (or 14 430 miles). More technical details and other information about the project are available here. The number of satellites is going to increase over time and, when operative, Galileo system will comprise 30 satellites (24 operational plus six spares).

How it works

Galileo will be equipped with the most accurate atomic clocks ever used for geolocalization (claimed error is one second in three million yearssource). These atomic clocks make it possible to send a very precise signal to the receivers: the time it takes for a signal to reach the ground determines the distance from a single satellite to the receiver. With 30 satellites available, 6-8 of them will always be accessible from any point on earth. A triangulation-like system is then used to unambiguously locate the receiver on the earth.

Galileo testing: current and future situation of Europe’s GNSS

Galileo is expected to be included in every new car sold in Europe starting from 2018, and should be 100% operational by 2020. Other possible applications that have been considered so far include financial transactions synchronization as well as telecommunication systems timing.

One of the last videos about the project, uploaded on YouTube by the ESA (European Space Agency) a few weeks ago, does a great job explaining the overall project status. This is why I decided to make it the first embedded video. It clearly explains where the services will be available and what made the project a reality. Before letting you watch it, though, I’d like to quote the video description given by ESA itself (part of it, actually):
With 18 Galileo satellites in orbit, supporting ground infrastructure, and after an extensive testing period, Galileo Initial Services are now available for public authorities, businesses and citizens. From now on, users around the world can be guided using the positioning, navigation and timing information provided by Galileo’s global satellite constellation.

Pretty exciting, don’t you think? ESA then goes on explaining what the next steps will be:

The Declaration of Galileo Initial Services by the European Commission is the first step towards reaching Full Operational Capability. The Initial Services offered by Galileo include the Open Service, the Public Regulated Service (PRS) and the Search and Rescue Service (SAR). The full and complete portfolio of Galileo services will be available by 2020, when the satellite constellation and ground infrastructure are complete.Galileo Initial Services are a result of cooperation between the European Commission, European GNSS Agency (GSA), and European Space Agency (ESA).


The following video explains what the project’s situation was a few years ago (2014):


Conclusion and further reference

The overall project is pretty huge, especially considering that the final cost is expected to be €3 billion. In less than two years Galileo will likely become a reality and people will probably talk more about it. For the moment, I hope this article was helpful and somehow more informative than some vague television content.

For up-to-date information regarding Galileo system, you can check out ESA’s website and this link. Other technical info, funding details and more in-depth descriptions can be found on Wikipedia and, of course, on the cited sources.

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