Satellites at Work

Most people meet space through their phone, the weather forecast and the television, not through a rocket launch. This chapter looks at the satellites that quietly do the work: the navigation system Galileo, the weather satellites that feed forecasts, and the communications satellites. It also explains who owns and runs them, since several different organisations are involved, and the division of work between ESA and the European Union becomes clear here. Dates and numbers are given from general knowledge and flagged where they should be checked.

Galileo: Europe's Own Satellite Navigation

Satellite navigation lets a receiver work out its position from signals sent by satellites. The best-known system is the American GPS, which was built and is run by the United States military. Europe's own system is Galileo, named after the Italian astronomer. The reasons for building it were similar to the reasons for building Ariane (Chapter 4): reliance on another country's system means relying on its decisions. Galileo is run under civilian control and not military control, and its signal is designed to be available whatever the political situation.

• Development. The first test satellites flew in the mid-2000s. The first operational satellites were launched in 2011, and initial services were declared in 2016 (check these dates).
• Size. A constellation of around thirty satellites in medium Earth orbit, of which most are in service.
• Services. A free open service for everyone, a high-accuracy option, and an encrypted service for government users called the Public Regulated Service.
• In your pocket. Many modern phones use Galileo signals alongside GPS, so a reader may be using it without knowing.

Timing, Not Only Position

Navigation satellites carry very accurate atomic clocks, and their signals are used as a source of precise time. Much of modern life depends on this: mobile phone networks, financial trading, electricity grids and data centres all use satellite time signals to keep their clocks aligned. Most users are unaware of it. For readers in IT, it is a reminder that a network clock can ultimately trace back to a satellite, and that a fault in such a system can have wide effects. Galileo suffered a prolonged outage of several days in 2019 (check the details), which was widely reported and showed the point.

Improving GPS: EGNOS

Before Galileo, Europe built a system called EGNOS, which corrects GPS signals over Europe and is used above all in aviation, to make landings and approaches safer. It is a good example of a European contribution to a system that Europe does not own.

Weather Satellites

Weather forecasts depend on satellites that watch clouds, temperatures and winds from orbit. The European satellites are the Meteosat series, which hover over a fixed point above the equator, and the MetOp satellites, which circle the Earth from pole to pole. They are operated not by ESA but by a separate organisation, EUMETSAT, a European body for weather satellites with its headquarters in Darmstadt, Germany. ESA develops the satellites and EUMETSAT runs them, which is another instance of the division of roles. A new generation of Meteosat satellites began to launch at the end of 2022 (check).

Communications

Communications satellites carry television, telephone traffic and data. ESA supports European industry in this field through programmes that help companies develop new satellites and technology, but most communications satellites are built and run by companies. The European operator Eutelsat began as an intergovernmental organisation and was later turned into a company, and in recent years it has merged with the OneWeb network (check). The EU has also planned a secure communications constellation of its own, partly in response to the growth of American constellations and to concerns about reliance on them. Plans like this change quickly, so check the current position.

How the Work Is Divided

Exercises

Next chapter: Partners, Rivals and Politics, which looks at NASA, Russia, China, Brexit and commercial competition.