The thermal behavior of the Thirty Meter Telescope (TMT) Telescope Structure (STR) and the STR mounted subsystems depends on the heat load of the System, the thermal properties of component materials and the environment as well as their interactions through convection, conduction and radiation. In this paper the thermal environment is described and the latest three-dimensional Computational Solid Dynamics (CSD) model is presented. The model tracks the diurnal temperature variation of the STR and the corresponding deformations. The resulting displacements are fed into the TMT Merit Function Routine (MFR), which converts them into translations and rotations of the optical surfaces. They, in turn, are multiplied by the TMT optical sensitivity matrix that delivers the corresponding pointing error. Thus the thermal performance of the structure can be assessed for requirement compliance, thermal drift correction strategies and look-up tables can be developed and design guidance can be provided. Results for a representative diurnal cycle based on measured temperature data from the TMT site on Mauna Kea and CFD simulations are presented and conclusions are drawn.

Date Published: 4 August 2014
PDF: 12 pages
Proc. SPIE 9150, Modeling, Systems Engineering, and Project Management for Astronomy VI, 915011 (4 August 2014); doi: 10.1117/12.2056582

Published in SPIE Proceedings Vol. 9150:
Modeling, Systems Engineering, and Project Management for Astronomy VI
George Z. Angeli; Philippe Dierickx, Editor(s)