![Top: Hexagonal segmented primary mirror designs with no central obscuration with different number of rings and varying segment sizes (flat-to-flat (m) 1-Hex: 2.64, 2-Hex: 1.45, 3-Hex: 1.19, 4-Hex: 0.85, 5-Hex: 0.66), all designs have an inscribed diameter of ∼6 m. Middle: Binary apodizer masks optimized for their respective aperture design. Bottom: Respective coronagraphic PSFs with an annular dark hole ranging from 3.4λ/D - 12λ/D, and a spatial average contrast floor of ∼4 × 10−11 inside the dark hole. -- [astro-ph.IM]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Segmentlevel.png?fit=1200%2C678&ssl=1)
[astro-ph.IM] Direct imaging and characterization of Earth-like planets require ultra-stable wavefronts to achieve a starlight suppression level of 100 parts per trillion (ppt) in the coronagraphic dark region of the host star. Thermal drifts in the telescope may affect the wavefront stability.
In this context, we present a segment-level thermal stability error budget for segmented space telescopes crucial to Earth-like planet detection and specify requirements for an ultra-stable telescope.
Our study utilizes multiple segmented primary mirror architectures, each with their respective apodizer solution developed by the Segmented Coronagraph Design & Analysis research team at the Space Telescope Science Institute, tailored to an off-axis ~6 m-aperture space telescope design.
Using a detailed finite element model provided by L3Harris Technologies, we relate the temperature gradient at the location of the primary mirror to wavefront variations on each segment. We allocate both static and dynamic thermal tolerances for each segment using the Pair-based Analytical model for Segmented Telescope Imaging from Space sensitivity approach, and a batch-estimation algorithm respectively.
Our analysis shows a non-uniform tolerance allocation across all segments of the primary mirror, as a result of apodization, and generally, with an increase in segment numbers, the tolerances for outer segments become less stringent. We observe trade-offs between segment size, tolerance relaxation and optimal wavefront sensing time to achieve a desired dark-hole contrast.
Ananya Sahoo, Laurent Pueyo, Iva Laginja, Bryony F. Nickson, Leonid Pogorelyuk, Laura E. Coyle, Rémi Soummer, Matthew East
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2607.28393 [astro-ph.IM] (or arXiv:2607.28393v1 [astro-ph.IM] for this version)
https://doi.org/10.48550/arXiv.2607.28393
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Journal reference: Sahoo, Ananya et al. “Segment-level thermal sensitivity analysis for exo-Earth coronagraphy with segmented space telescopes,” Journal of Astronomical Telescopes, Instruments, and Systems 12(4), 041029 (27 Jul 2026)
Related DOI:
https://doi.org/10.1117/1.JATIS.12.4.041029
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Submission history
From: Ananya Sahoo
[v1] Thu, 30 Jul 2026 15:48:05 UTC (21,878 KB)
https://arxiv.org/abs/2607.28393
Astrobiology, Astronomy,
