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Proceedings Paper • Open Access

Optical aperture synthesis: limitations and interest for the earth observation
Author(s): Laurent Brouard; Frederic Safa; Vincent Crombez; David Laubier

Paper Abstract

For very large telescope diameters, typically above 4 meters, monolithic telescopes can hardly be envisaged for space applications. Optical aperture synthesis can be envisaged in the future for improving the image resolution from high altitude orbits by co-phasing several individual telescopes of smaller size and reconstituting an aperture of large surface. The telescopes can be deployed on a single spacecraft or distributed on several spacecrafts in free flying formation. Several future projects are based on optical aperture synthesis for science or earth observation. This paper specifically discusses the limitations and interest of aperture synthesis technique for Earth observation from high altitude orbits, in particular geostationary orbit. Classical Fizeau and Michelson configurations are recalled, and system design aspects are investigated: synthesis of the Modulation Transfer Function (MTF), integration time and imaging procedure are first discussed then co-phasing strategies and instrument metrology are developed. The discussion is supported by specific designs made at EADS Astrium. As example, a telescope design is presented with a surface of only 6.6 m2 for the primary mirror for an external diameter of 10.6 m allowing a theoretical resolution of 1.2 m from geostationary orbit with a surface lower than 10% of the overall surface. The impact is that the integration time is increasing leading to stringent satellite attitude requirements. Image simulation results are presented. The practical implementation of the concept is evaluated in terms of system impacts in particular spacecraft attitude control, spacecraft operations and imaging capability limitations.

Paper Details

Date Published: 21 November 2017
PDF: 6 pages
Proc. SPIE 10567, International Conference on Space Optics — ICSO 2006, 1056709 (21 November 2017); doi: 10.1117/12.2308167
Show Author Affiliations
Laurent Brouard, EADS Astrium SAS (France)
Frederic Safa, EADS Astrium SAS (France)
Vincent Crombez, EADS Astrium SAS (France)
David Laubier, Ctr. National d'Études Spatiales (France)

Published in SPIE Proceedings Vol. 10567:
International Conference on Space Optics — ICSO 2006
Errico Armandillo; Josiane Costeraste; Nikos Karafolas, Editor(s)

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