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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The VLT Active Optics System provides complete control of the VLT optics and optimises its performance in all telescope positions. This is achieved by changing the shape of the primary 8.2-metre Zerodur mirror and also shifting the position of the secondary 1.1-metre beryllium mirror at the top of the telescope structure. A stellar image is registered by the ‘wavefront sensor’ and analysed, after which corresponding correction signals are generated to move the mirror supports.