The integration and testing of XMM

The XMM (X-ray Multi-Mirror) spacecraft, a spaceborne X-ray observatory to be launched by Ariane-5, stands 10 m high and measures over 4 m in diameter in launch configuration, for a launch mass of just under four tons. Such a tall spacecraft challenges the capabilities of existing European environmental testing facilities. Provisions were made iri the design for a split according to geometry into an Upper Module and a Lower Module for environmental test purposes. Optical testing of the X-ray Mirror Modules - the core technological challenge - required the use of several existing and custom-built test facilities. In the face of strict schedule requirements, spacecraft-level test flows were organised around extensively parallel flows and all tests were scrutinised for their potential for early problem identification. This article briefly introduces the XMM configuration and schedule constraints, explains the spacecraft-level model philosophy, discusses the consequences for each category of test in terms of facility and test specimen configurations, and summarises the spacecraft test flows and the results achieved.