XMM receives its golden eyes !
1 April 1999ESA's X-ray space observatory XMM, currently being assembled in view of a launch from Kourou next January, has been fitted with its three X-ray telescopes - the extremely high-precision Mirror Modules, each with its 58 wafer-thin gold-covered mirror shells which will give the mission its unprecedented vision of the X-ray universe.
The telescopes have now all been fitted to the spacecraft's lower platform, which has completed most of its environmental tests at ESA's ESTEC Technical Centre at Noordwijk in the Netherlands. At the end of February, the three structural and thermal models of the telescopes, used during these tests, were removed to make way for those that will fly on the spacecraft.
The positioning of the first of XMM's 'golden eyes' began on 24 March. Operations took place in an ultra-clean 'class 100' tent situated in the ESTEC satellite test area. A small team of engineers from prime contractor Daimler-Chrysler Aerospace (Dornier) and from ESA wore special suits to avoid any contamination of the flight hardware as they carefully moved the telescope vertically into the waiting orifice on the satellite. Once slotted in, the first telescope was fixed to its mounting interface by means of six bolts and 3 centring pins around its external circumference.
These delicate operations were repeated for the second telescope on 26 March, and the third telescope was placed in position on 30 March. After each mounting, precise measurements were taken with micrometer gauges to evaluate any deformation to the satellite platform due to the added mass of the telescopes, weighting in total 1420 kg. When all was finished, engineers were pleased to announce that the deformation of the platform was low, below 10 microns, and they confirmed that there were no undue loads on the spacecraft.
Before the lower half of XMM is mated to the focal plane assembly, scheduled at the end of May, one further XMM 'eye' will be added: the Optical Monitor. This telescope which will observe the heavens in the visible and ultraviolet, is due to be fitted in the third week of April.