Space Telescope Design to Directly Image the Habitable Zone of Alpha Centauri

The scientific interest in directly image and identifying Earth-like planets within the Habitable Zone (HZ) around nearby stars is driving the design of specialized direct imaging mission 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 arcseconds respectively. This enables direct imaging of the system with a 0.3m class telescope. Contrast ratios in the order of 1e-10 are needed to image Earth-brightness planets. Low-resolution (5-band) spectra of all planets, will 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 Induce 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 high-precision 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 percent completeness detections of Earth-like planets.

Eduardo Bendek, Ruslan Belikov, Julien Lozi, Sandrine Thomas, Jared Males, Sasha Weston, Michael McElwain
(Submitted on 8 Oct 2015)
Comments: Presented at SPIE Optics and Photonics 2015
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:1510.02489 [astro-ph.IM] (or arXiv:1510.02489v1 [astro-ph.IM] for this version)
Submission history
From: Eduardo Bendek
[v1] Thu, 8 Oct 2015 20:08:40 GMT (9160kb)
http://arxiv.org/abs/1510.02489