IBISSTM: Mechanical and thermal model, design and tests

The IBIS Structural and Thermal Model, STM, is the first instrument model t o be completed during the development phase of IBIS. According to the STM p lanning the Spacecraft integration was in April/May, and the test program l asts from June to October 1998. This paper describes mechanical design choi ces and implementations, as well as results from environmental testing. Ana lysis and tests will verify the validity of the design in view of the two m ajor questions that have been faced in the STM design: detector weight and thermal design. Details will be given on the main parts of IBIS, like the M ask (188 kg), the Detector Structure (71 kg), and the heavy shielding both active (193 kg) and passive. Finally the thermal problem connected to the l arge number of detectors (about 20.000 pixels) will be discussed.