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Augmented Method to Improve Thermal Data for the Figure Drift Thermal Distortion Predictions of the JWST OTIS Cryogenic Vacuum Test
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Author and Affiliation:
Park, Sang C.(Smithsonian Astrophysical Observatory, Cambridge, MA, United States);
Carnahan, Timothy M.(NASA Goddard Space Flight Center, Greenbelt, MD United States);
Cohen, Lester M.(Smithsonian Astrophysical Observatory, Cambridge, MA, United States);
Congedo, Cherie B.(SGT, Inc., Greenbelt, MD, United States);
Eisenhower, Michael J.(Smithsonian Astrophysical Observatory, Cambridge, MA, United States);
Ousley, Wes(Genesis Engineering Solutions, Inc., Lanham, MD, United States);
Weaver, Andrew(ATA Aerospace LLC, Greenbelt, MD, United States);
Yang, Kan(NASA Goddard Space Flight Center, Greenbelt, MD United States)
Abstract: The JWST Optical Telescope Element (OTE) assembly is the largest optically stable infrared-optimized telescope currently being manufactured and assembled, and is scheduled for launch in 2018. The JWST OTE, including the 18 segment primary mirror, secondary mirror, and the Aft Optics Subsystem (AOS) are designed to be passively cooled and operate near 45K. These optical elements are supported by a complex composite backplane structure. As a part of the structural distortion model validation efforts, a series of tests are planned during the cryogenic vacuum test of the fully integrated flight hardware at NASA JSC Chamber A. The successful ends to the thermal-distortion phases are heavily dependent on the accurate temperature knowledge of the OTE structural members. However, the current temperature sensor allocations during the cryo-vac test may not have sufficient fidelity to provide accurate knowledge of the temperature distributions within the composite structure. A method based on an inverse distance relationship among the sensors and thermal model nodes was developed to improve the thermal data provided for the nanometer scale WaveFront Error (WFE) predictions. The Linear Distance Weighted Interpolation (LDWI) method was developed to augment the thermal model predictions based on the sparse sensor information. This paper will encompass the development of the LDWI method using the test data from the earlier pathfinder cryo-vac tests, and the results of the notional and as tested WFE predictions from the structural finite element model cases to characterize the accuracies of this LDWI method.
Publication Date: Aug 06, 2017
Document ID:
20170007442
(Acquired Aug 11, 2017)
Subject Category: SPACECRAFT DESIGN, TESTING AND PERFORMANCE; OPTICS
Report/Patent Number: GSFC-E-DAA-TN44813
Document Type: Conference Paper
Meeting Information: SPIE Optics + Photonics 2017; 6-10 Aug. 2017; San Diego, CA; United States
Meeting Sponsor: International Society for Optical Engineering; Bellingham, WA, United States
Contract/Grant/Task Num: NNG15CR64C; NNG14FC86T; NNX13AI83A
Financial Sponsor: NASA Goddard Space Flight Center; Greenbelt, MD United States
Organization Source: NASA Goddard Space Flight Center; Greenbelt, MD United States
Description: 13p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright; Distribution as joint owner in the copyright
NASA Terms: JAMES WEBB SPACE TELESCOPE; INFRARED TELESCOPES; COMPOSITE STRUCTURES; TEMPERATURE DISTRIBUTION; TEMPERATURE SENSORS; VACUUM TESTS; CRYOGENICS; CIRCUIT BOARDS; MIRRORS; STRUCTURAL MEMBERS; TELESCOPES; WAVE FRONTS
Other Descriptors: JWST; THERMAL DISTORTION; NANOMETER; COMPOSITE; MODEL VALIDATION; THERMAL MODELING
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