XMM is the largest scientific satellite ever built in Europe. It is ten meters long and nearly four tons in mass. The long wide tube accommodating the focal length of the X-ray telescopes dominates the the design of the satellite. On the left side one can see the mirror modules housing the three nested Wolter I telescopes, with a focal length of 7.5 m. At the right end of the telescope the X-ray detectors and spectrographs are mounted in the foci of the telescopes, in the focal plane assembly.
Graphics: Courtesy of the Dornier Satellitensysteme GmbH