The Giant Magellan Telescope (GMT) will be a 25 meter optical telescope with a maximum weight of about 2300t, located on Cerro Las Campanas in Chile. The telescope will be equipped with a complex adaptive optical system as well as highly sensitive instrumentation and high performance drive and control components like direct drives and high resolution band encoders. For protection of this sensitive equipment from extreme earthquake excitations, a seismic isolation system implemented at the base of the concrete telescope pier will reduce horizontal accelerations. A second earthquake damping system, currently under development at OHB, will be installed on the GMT Mount to suppress vertical accelerations. In addition to the damping system itself, adaptations need to be made to the drive and control components to allow the damping system movements without having an impact on their functionality. A prototype of the vertical damping system will be built and dynamic testing will be performed. The presentation will provide an overview on the system development status.
In this paper, the thermal design of the GMT elevation drive’s active segments (forcers) is presented. The design goal is to keep the forcer housing temperature during observation within a band of −2 K to +1 K with respect to the ambient temperature. The key drivers of the forcer thermal design are described and verified for a constant load by computational fluid dynamics (CFD) simulation. Additionally, a temperature feedback control loop is introduced to manage the high dynamic load variations occurring during observation. The dynamic simulation results of the temperature control are provided by the lumped parameters thermal modelling approach and confirm the forcer to stay within the defined temperature range.
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