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Proceedings Paper

Space telescope design to directly image the habitable zone of Alpha Centauri
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Paper Abstract

The scientific interest in directly imaging and identifying Earth-like planets within the Habitable Zone (HZ) around nearby stars is driving the design of specialized direct imaging missions such as ACESAT, EXO-C, EXO-S and AFTA-C. The inner edge of Alpha Cen A and B Habitable Zone is found at exceptionally large angular separations of 0.7” and 0.4” respectively. This enables direct imaging of the system with a 0.3m class telescope. Contrast ratios on the order of 1010 are needed to image Earth-brightness planets. Low-resolution (5-band) spectra of all planets may allow establishing the presence and amount of an atmosphere. This star system configuration is optimal for a specialized small, and stable space telescope that can achieve high-contrast but has limited resolution. This paper describes an innovative instrument design and a mission concept based on a full Silicon Carbide off-axis telescope, which has a Phase Induced Amplitude Apodization coronagraph embedded in the telescope. This architecture maximizes stability and throughput. A Multi-Star Wave Front algorithm is implemented to drive a deformable mirror controlling simultaneously diffracted light from the on-axis and binary companion star. The instrument has a Focal Plane Occulter to reject starlight into a highprecision pointing control camera. Finally we utilize a Orbital Differential Imaging (ODI) post-processing method that takes advantage of a highly stable environment (Earth-trailing orbit) and a continuous sequence of images spanning 2 years, to reduce the final noise floor in post processing to ~2e-11 levels, enabling high confidence and at least 90% completeness detections of Earth-like planets.

Paper Details

Date Published: 16 September 2015
PDF: 15 pages
Proc. SPIE 9605, Techniques and Instrumentation for Detection of Exoplanets VII, 960516 (16 September 2015); doi: 10.1117/12.2188999
Show Author Affiliations
Eduardo A. Bendek, NASA Ames Research Ctr. (United States)
Ruslan Belikov, NASA Ames Research Ctr. (United States)
Julien Lozi, Subaru Telescope, National Astronomical Observatory of Japan (United States)
Sandrine Thomas, NASA Ames Research Ctr. (United States)
Jared Males, The Univ. of Arizona (United States)
Sasha Weston, NASA Ames Research Ctr. (United States)
Michael McElwain, NASA Goddard Space Flight Ctr. (United States)

Published in SPIE Proceedings Vol. 9605:
Techniques and Instrumentation for Detection of Exoplanets VII
Stuart Shaklan, Editor(s)

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