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Proceedings Paper

X-array aperture configuration in planar or non-planar spacecraft formation for Darwin/TPF-I candidate architectures
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Paper Abstract

The missions DARWIN and TPF-I (Terrestrial Planet Finder-Interferometer) aim at the search and analysis of terrestrial exo-planets orbiting nearby stars. The major technical challenge is the huge contrast ratio and the small angular separation between star and planet. The observational method to be applied is nulling interferometry. It allows for extinguishing the star light by several orders of magnitude and, at the same time, for resolving the faint planet. The fundamental performance of the nulling interferometer is determined by the aperture configuration, the effective performance is driven by the actual instrument implementation. The x-Array, an aperture configuration with 4 telescopes allowing for phase chopping and decoupling of the nulling and imaging properties, provides highest instrument performance. The scientific goals necessitate an instrument setup of high efficiency and utmost symmetry between the beams concerning optical path length, beam profile and state of polarization. Non-planar spacecraft formations allow for a simpler spacecraft design which comes at the cost of inherent constellation and beam asymmetry, of increased complexity of the beam relay optics and of instrumental errors synchronous to the planet signal demodulation frequency. Planar formations allow for perfect efficiency and symmetry but need deployable structures for the secondary mirror and the sunshield due to launcher accommodation constraints. We present a discussion of planar and non-planar implementations of the x-Array aperture configuration and identify for both the critical items and design drivers. We compare the achievable instrument performance and point out the constraints for each spacecraft formation.

Paper Details

Date Published: 19 September 2007
PDF: 10 pages
Proc. SPIE 6693, Techniques and Instrumentation for Detection of Exoplanets III, 66930U (19 September 2007); doi: 10.1117/12.733820
Show Author Affiliations
Oswald Wallner, EADS Astrium GmbH (Germany)
Klaus Ergenzinger, EADS Astrium GmbH (Germany)
Reinhold Flatscher, EADS Astrium GmbH (Germany)
Ulrich Johann, EADS Astrium GmbH (Germany)

Published in SPIE Proceedings Vol. 6693:
Techniques and Instrumentation for Detection of Exoplanets III
Daniel R. Coulter, Editor(s)

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