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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For the concept of integrity applied to aircraft navigation via satellite navigation, imagine the aircraft in question with horizontal and vertical circles around it, taking in all the permissible places it might be, known as its ‘protection levels’. Around these in turn are wider circles representing its ‘alert level’ – so called because when the combined uncertainty level reaches this threshold then an alarm is raised to the user. The aim is to provide full confidence in the navigation system, including the ability to detect when the system should not be used for navigation.