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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Stacks of carefully polished, coated and cut silicon wafers – normally used to manufacture integrated circuits – that will focus X-rays inside ESA’s Athena space observatory, due for launch in 2028.
Invisible X-rays tell us about the very hot matter in the Universe – black holes, supernovas and superheated gas clouds. But energetic X-rays do not behave like typical light waves – try to reflect them with a standard mirror and they are absorbed. Instead, X-rays can only be reflected at shallow angles, like stones skimming across water.
That means multiple mirrors must be stacked together to build a telescope. ESA has developed ‘silicon pore optics’ to see much further into space than the ageing XMM-Newton X-ray observatory.
This approach is based on industrial silicon wafers, taking advantage of their stiffness and super-polished surface. Grooves are cut into the wafers to form pores through which the X-rays are focused. A few dozen at a time are stacked together to form a single mirror module. Many hundreds of these modules will be combined to form the optics of the X-ray mission.
To find out more, check our video interview with ESA optics engineer Eric Wille.