Science-Driven Performance Requirements for UV Coronagraph Design: Implications for O3 Detection in Earth-like Atmospheres
Abstract
Detecting biosignatures on Earth-like exoplanets from the Proterozoic era requires instrumentation capable of probing near-ultraviolet (NUV) spectral features, particularly ozone (\ce{O3}), which serves as an indirect proxy for molecular oxygen (\ce{O2}) when direct detection is challenging. Using a combination of photochemical-climate modeling and atmospheric retrieval simulations, we quantify fiducial instrument performance requirements for robust \ce{O3} detection and assess the risk of spectral false positives from sulfur dioxide (\ce{SO2}). Our analysis demonstrates the \ce{O3} abundances for Proterozoic Earth-like planets with \ce{O2} as low as 0.1\% the present atmospheric level, can be constrained to within an order of magnitude at 1\,σ confidence using three adjacent photometric bandpasses at a signal-to-noise ratio of 10 at 0.366\,upmum, each with a 15\% width, and a short wavelength cutoff for those observations near 0.26\,upmum. The self-consistent steady state atmospheric modeling results show that \ce{SO2} buildup is difficult in a habitable environment with appreciable amounts of water vapor in its atmosphere and would require volcanic outgassing rates at least two orders of magnitude above present-day Earth to reach surface abundance levels comparable to Proterozoic Earth-like abundances of \ce{O3}. Even under these high \ce{SO2} flux scenarios, \ce{SO2} remains largely unconstrained with the recommended observational configuration, reinforcing the need for NUV coverage in coronagraphic instruments. Our findings support the inclusion of UV-optimized optics and detectors on the Habitable Worlds Observatory (HWO) to enable biosignature detection strategies sensitive to atmospheric conditions across key phases of Earth's geological history.
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BibTeX
@misc{young2026sciencedriven,
title = {{Science-Driven Performance Requirements for UV Coronagraph Design: Implications for O$_3$ Detection in Earth-like Atmospheres}},
author = {Amber V. Young and Giada Arney and Shawn Domagal-Goldman and Tyler D. Robinson and Roser Juanola-Parramon and Christopher Stark and Renyu Hu and Armen Tokadjian and Mario Damiano},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.19081},
eprint = {2610.19081},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.19081},
}
RIS
TY - UNPB
TI - Science-Driven Performance Requirements for UV Coronagraph Design: Implications for O_3 Detection in Earth-like Atmospheres
AU - Amber V. Young
AU - Giada Arney
AU - Shawn Domagal-Goldman
AU - Tyler D. Robinson
AU - Roser Juanola-Parramon
AU - Christopher Stark
AU - Renyu Hu
AU - Armen Tokadjian
AU - Mario Damiano
PY - 2026
DA - 2026/10/13
PB - arXiv
DO - 10.48550/arxiv.2610.19081
UR - https://arxiv.org/abs/2610.19081
AB - Detecting biosignatures on Earth-like exoplanets from the Proterozoic era requires instrumentation capable of probing near-ultraviolet (NUV) spectral features, particularly ozone (\ce{O3}), which serves as an indirect proxy for molecular oxygen (\ce{O2}) when direct detection is challenging. Using a combination of photochemical-climate modeling and atmospheric retrieval simulations, we quantify fiducial instrument performance requirements for robust \ce{O3} detection and assess the risk of spectral false positives from sulfur dioxide (\ce{SO2}). Our analysis demonstrates the \ce{O3} abundances for Proterozoic Earth-like planets with \ce{O2} as low as 0.1\% the present atmospheric level, can be constrained to within an order of magnitude at 1\,σ confidence using three adjacent photometric bandpasses at a signal-to-noise ratio of 10 at 0.366\,upmum, each with a 15\% width, and a short wavelength cutoff for those observations near 0.26\,upmum. The self-consistent steady state atmospheric modeling results show that \ce{SO2} buildup is difficult in a habitable environment with appreciable amounts of water vapor in its atmosphere and would require volcanic outgassing rates at least two orders of magnitude above present-day Earth to reach surface abundance levels comparable to Proterozoic Earth-like abundances of \ce{O3}. Even under these high \ce{SO2} flux scenarios, \ce{SO2} remains largely unconstrained with the recommended observational configuration, reinforcing the need for NUV coverage in coronagraphic instruments. Our findings support the inclusion of UV-optimized optics and detectors on the Habitable Worlds Observatory (HWO) to enable biosignature detection strategies sensitive to atmospheric conditions across key phases of Earth's geological history.
ER -