Figure 6-30: Three Orbiting X-Ray Observatories (a) X-rays are absorbed by ordinary mirrors like those used in optical reflectors, but they can be reflected if they graze the mirror surface at a very shallow angle. In the Chandra X-ray Observatory, X-rays are focused in this way onto a focal plane 10 m (33 ft) behind the mirror. (b) XMM-Newton is about the same size as Chandra, and its three X-ray telescopes form images in the same way. (c) NuSTAR has a 33-foot (10-meter) mast that deploys after launch to separate the optics modules (right) from the detectors in the focal plane (left)

(a: NASA/Chandra X-ray Observatory Center/Smithsonian Astrophysical Observatory; b: D. Ducros/European Space Agency; c: NASA)