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Proceedings Paper

JWST's cryogenic position metrology system
Author(s): Tony L. Whitman; Randolph P. Hammond; Joe Orndorff; Stephen Hope; Stephen A. Smee; Thomas Scorse; Keith A. Havey
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Paper Abstract

The James Webb Space Telescope will undergo a full system test in the cryogenic vacuum chamber A at the Johnson Spaceflight Center in order to verify the overall performance of the combined telescope and instrument suite. This will be the largest and most extensive cryogenic test ever undertaken. Early in the test system development, it was determined that precise position measurements of the overall hardware would enhance the test results. Various concepts were considered before selecting photogrammetry for this metrology. Photogrammetry has been used in space systems for decades, however cryogenic use combined with the size and the optical/thermal sensitivity of JWST creates a unique set of implementation challenges. This paper provides an overview of the JWST photogrammetric system and mitigation strategies for three key engineering design challenges: 1) the thermal design of the viewing windows to prevent excessive heat leak and stray light to the test article 2) cost effective motors and mechanisms to provide the angle diversity required, and 3) camera-flash life and reliability sufficient for inaccessible use during the number and duration of the cryogenic tests.

Paper Details

Date Published: 21 September 2012
PDF: 16 pages
Proc. SPIE 8442, Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave, 84422L (21 September 2012); doi: 10.1117/12.926565
Show Author Affiliations
Tony L. Whitman, ITT Exelis Geospatial Systems (United States)
Randolph P. Hammond, The Johns Hopkins Univ. (United States)
Joe Orndorff, The Johns Hopkins Univ. (United States)
Stephen Hope, The Johns Hopkins Univ. (United States)
Stephen A. Smee, The Johns Hopkins Univ. (United States)
Thomas Scorse, ITT Exelis Geospatial Systems (United States)
Keith A. Havey, ITT Exelis Geospatial Systems (United States)


Published in SPIE Proceedings Vol. 8442:
Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave
Mark C. Clampin; Giovanni G. Fazio; Howard A. MacEwen; Jacobus M. Oschmann, Editor(s)

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