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Proceedings Paper • Open Access

Darwin : the technical challenges of an optical nulling interferometer in space
Author(s): Thierry Viard; Glenn Lund; Eric Thomas; Michel Vacance

Paper Abstract

Alcatel Space has been responsible for a feasibility study contract, awarded by the European Space Agency, and dedicated to the definition of preliminary interferometric concepts for the direct detection and characterisation of exo-planets associated with nearby stars.

The retained concept is a six free-flyer-telescope interferometer, with a variable baseline ranging from 50 to 500 m. The collected wavefronts are combined on a 7th free-flying hub satellite at the centre of the array, and the observations are performed in the thermal Infra-Red spectral band. The latter choice is made for two reasons : firstly, the wavelength providing optimal contrast between the planetary and stellar (background) signals is approximately 10μm; secondly, the spectral features of interest for the detection of life as we know it (CO2, H2O, O3 , CH4 ... ) lie in the band between 6 and 18 μm.

The system requirements for such an instrument are very severe, owing to the physical nature of the mission concept; i.e. that of a coronographic stellar interferometer: in order to achieve satisfactory extinction of the unwanted flux generated by the central star, such a concept will impose the control of optical pathlength differences between telescopes to within a small fraction of a wavelength, milli-arcsec pointing stabilities, 10-3 amplitude equalisation, achromatic check-shifts of some beams with respect to the others, and the use of passively cooled cryogenic telescopes.

Paper Details

Date Published: 21 November 2017
PDF: 10 pages
Proc. SPIE 10569, International Conference on Space Optics — ICSO 2000, 1056910 (21 November 2017); doi: 10.1117/12.2307876
Show Author Affiliations
Thierry Viard, Alcatel Space Industries (France)
Glenn Lund, Alcatel Space Industries (France)
Eric Thomas, Alcatel Space Industries (France)
Michel Vacance, Alcatel Space Industries (France)

Published in SPIE Proceedings Vol. 10569:
International Conference on Space Optics — ICSO 2000
Georges Otrio, Editor(s)

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