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Proceedings Paper

The SOFIA cavity door - an unvignetted view: configuration, operation, and potential science implications
Author(s): Edwin F. Erickson; David A. Howe; John N. Perry; Ted M. Brown; Michael R. Haas
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Paper Abstract

The 2.5 meter (m) effective diameter telescope on SOFIA - the Stratospheric Observatory for Infrared Astronomy - will operate in an open-port cavity which will be closed below operating altitudes by a cavity-door assembly. When operating, the telescope will view the sky through an aperture defined by an aperture assembly (AA) with a nearly rectangular opening extending 112 inches (2.84 m) in elevation (roll) and 129 inches (3.27 m) in cross-elevation. The aperture will be servo-controlled in roll to track the telescope elevation (EL), and the aircraft heading will be adjusted to maintain the telescope centered on the aperture in cross-elevation (XEL). An upper rigid door (URD) and lower flexible door (LFD) move with the aperture to minimize the opening into the cavity containing the telescope. This paper describes basic parameters of the door system, and estimates possible science impacts of its specification, configuration and planned operation. Topics included are the geometry, expected aerodynamic disturbances, control system, gear life, influences of radiative and diffraction effects on science instrument performance, testing, operational considerations, and development status. As designed, the door system is expected not to limit the performance of science instruments or observatory operational efficiency, but several potential concerns are considered. These include modulation of stray and diffracted radiation, reliability, and maintainability.

Paper Details

Date Published: 23 June 2006
PDF: 11 pages
Proc. SPIE 6267, Ground-based and Airborne Telescopes, 62670U (23 June 2006); doi: 10.1117/12.672639
Show Author Affiliations
Edwin F. Erickson, NASA Ames Research Ctr. (United States)
David A. Howe, NASA Ames Research Ctr. (United States)
John N. Perry, NASA Ames Research Ctr. (United States)
Ted M. Brown, NASA Ames Research Ctr. (United States)
Michael R. Haas, NASA Ames Research Ctr. (United States)


Published in SPIE Proceedings Vol. 6267:
Ground-based and Airborne Telescopes
Larry M. Stepp, Editor(s)

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