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 optical design of ESA's XMM observatory illustrated by one of the three mirror modules. The optical design not only provides high throughput and large bandwidth, but also achieve the medium-resolution goal of 20-30 arcsec on-axis. The high throughput is achieved by nesting a large number of Wolter-1 shells, as shown in the figure. The X-ray telescope uses the principle of grazing-incidence (at about 0.5deg) X-ray reflection to reflect and image the X-rays from gold-coated paraboloid and hyperboloid surfaces (see inset). The other two main parts of the X-ray payload elements are a CCD array (EPIC) and a reflection-grating spectrometer (RGS), which fit behind each mirror module. The CCD array is the prime-focus camera, which will perform the mission's broadband (0.1-10 keV) imaging and spectroscopically resolve the helium-like and hydrogenic K lines from most of the abundant elements. [Image Date: 01-02-97] [97.12.016-001]