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Proceedings Paper

Structural-thermal-optical performance (STOP) sensitivity analysis for the James Webb Space Telescope
Author(s): Carl Blaurock; Mark McGinnis; Kevin Kim; Gary E. Mosier
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Paper Abstract

The James Webb Space Telescope (JWST) is a key component of NASA's Origins Program to understand the origins and future of the universe. JWST will be used to study the birth and formation of galaxies and planets. The mission requires a large (25m2 aperture) but extremely stable (150 nm RMS wave front error) optical platform, where performance is a tightly coupled function of numerous physical processes. Distortion due to thermal loading is a significant error source. The process by which predicted heat loads are mapped to optical error is termed Structural-Thermal-Optical Performance (STOP) modeling. Thermal-optical performance is a function of heat loads, thermal properties (conductivities, radiative coupling coefficients), structural properties (moduli, geometry, thermal expansion coefficients, ply layup angles), and optical sensitivities. Sensitivities, the gradients of performance with respect to design parameters, give a direct way to identify the parameters that have the largest influence on performance. Additionally, gradients can identify the largest sources of uncertainty, and thus contribute to improving the robustness of the design, either via redesign or by placing requirements on parameter variability. The paper presents a general framework for developing the analytical sensitivities of the STOP prediction using the Chain Rule. The paper focuses on solving for the sensitivities of the steady-state, conduction-only, problem, using discipline modeling tools (thermal, structural, and optical) to compute the terms in the STOP gradients. The process is demonstrated on the SDR2 Rev. 1 cycle of the JWST modeling effort.

Paper Details

Date Published: 18 August 2005
PDF: 11 pages
Proc. SPIE 5867, Optical Modeling and Performance Predictions II, 58670V (18 August 2005); doi: 10.1117/12.618697
Show Author Affiliations
Carl Blaurock, Nightsky Systems, Inc. (United States)
Mark McGinnis, Swales Aerospace Corp. (United States)
Kevin Kim, Swales Aerospace Corp. (United States)
Gary E. Mosier, NASA Goddard Space Flight Ctr. (United States)

Published in SPIE Proceedings Vol. 5867:
Optical Modeling and Performance Predictions II
Mark A. Kahan, Editor(s)

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