The European Space Agency (ESA) is Europe’s gateway to space. Its mission is to shape the development of Europe’s space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world.
Find out more about space activities in our 23 Member States, and understand how ESA works together with their national agencies, institutions and organisations.
Exploring our Solar System and unlocking the secrets of the Universe
Go to topicProtecting life and infrastructure on Earth and in orbit
Go to topicUsing space to benefit citizens and meet future challenges on Earth
Go to topicMaking space accessible and developing the technologies for the future
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There is lot more to Galileo than just its satellites in space. A global ground network is essential to ensure the continued reliability of the time and positioning information embedded within the signals from orbit. Galileo’s worldwide ground segment has been described as the most complex system ever developed by ESA. It is divided into two segments: the Galileo Mission Segment, which oversees the functioning of the satellites’ navigation payloads including the generation of their signal messages, and the GCS that oversees the functioning of the satellites themselves.