An Overview of the XMM Observatory System

H. Barré, H. Nye & G. Janin

XMM is the largest scientific observatory developed by ESA and dedicated to exploring the Universe in the soft-X-ray portion of the electromagnetic spectrum. This article presents XMM as a complete system, composed by the space segment (the satellite and its launch vehicle) and the ground segment (all of ground-based infrastructure needed to control the satellite and gather the scientific data). The definition of the XMM orbit, which is also described, is a key element in meeting the primary mission objectives and satisfying the project programmatic requirements and constraints.