XMM flight model assembly

XMM's upper and lower modules are mated on 26 May 1999 in the cleanroom facilities of ESTEC's Test Centre. Over the past months, both halves parts of the spacecraft have independently completed their environmental tests at ESTEC. The upper focal plane assembly was hoisted by a gantry crane above XMM's lower section. After being lowered into place, the first of 64 bolts around the 6 m diameter interface plane was inserted. To mark this milestone, 3 years after the start of construction of flight hardware, a special 'golden bolt' was included. After the mating, the fully assembled satellite went on to complete acoustic tests at ESTEC. The schedule is to have the satellite in Kourou by end-September, with a campaign leading to a launch in December 1999. ESA's X-ray Multi-Mirror (XMM) high-throughput X-ray spectroscopy mission will be launched by Ariane-5. By virtue of its large collecting area and highly eccentric orbit, the 3.9-tonne XMM will make long observations of soft X-ray (100 eV to 12 keV) sources with unprecedented sensitivity. Most of the 50-200 sources in every image will be revealed for the first time. Whereas the German/US/UK Rosat mission, launched in 1990, pushed the number of known X-ray sources to 120 000, XMM will see millions. [Image Date: 1999/03] [99.05.010-034]