Exoplanetology: Exoplanets & Exomoons

Retrievals Applied To A Decision Tree Framework Can Characterize Earth-like Exoplanet Analogs

By Keith Cowing

Status Report

astro-ph.EP

November 14, 2023

Filed under Analog, Archean Earth, astro-ph.EP, biosignature, exoplanet, habitability, Habitable Worlds Observatory

Retrievals Applied To A Decision Tree Framework Can Characterize Earth-like Exoplanet Analogs — Modeled Haze free Archean Earth Spectrum. Shown here is the planet-to-star flux ratio vs wavelength and in black is the simulated spectrum for a haze free Archean Earth-like planet around the sun. The spectral bandpasses from the Archean Earth pathway on the decision tree are shown where the 0.89 µm bandpass is shaded in green and the 1.65 µm bandpass is shaded in red. The Rayleigh scattering slope and species absorption features are labeled in text. Also shown is an SNR 10 error bar scaling indicative of the simulated observations for each singular bandpass and combination. — astro-ph.EP

Exoplanet characterization missions planned for the future will soon enable searches for life beyond our solar system. Critical to the search will be the development of life detection strategies that can search for biosignatures while maintaining observational efficiency.

In this work, we adopted a newly developed biosignature decision tree strategy for remote characterization of Earth-like exoplanets. The decision tree offers a step-by-step roadmap for detecting exoplanet biosignatures and excluding false positives based on Earth’s biosphere and its evolution over time.

We followed the pathways for characterizing a modern Earth-like planet and an Archean Earth-like planet and evaluated the observational trades associated with coronagraph bandpass combinations of designs consistent with The Habitable Worlds Observatory (HWO) precursor studies. With retrieval analyses of each bandpass (or combination), we demonstrate the utility of the decision tree and evaluated the uncertainty on a suite of biosignature chemical species and habitability indicators (i.e., the gas abundances of H2O, O2, O3, CH4, and CO2).

Notably for modern Earth, less than an order of magnitude spread in the 1-σ uncertainties were achieved for the abundances of H2O and O2, planetary surface pressure, and atmospheric temperature with three strategically placed bandpasses (two in the visible and one in the near-infrared). For the Archean, CH4 and H2O were detectable in the visible with a single bandpass.

Amber V. Young, Jaime Crouse, Giada Arney, Shawn Domagal-Goldman, Tyler D. Robinson, Sandra T. Bastelberger

Comments: Planetary Science Journal. For Source Data see this https URL
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2311.07530 [astro-ph.EP] (or arXiv:2311.07530v1 [astro-ph.EP] for this version)
Submission history
From: Amber Young
[v1] Mon, 13 Nov 2023 18:16:16 UTC (2,249 KB)
https://arxiv.org/abs/2311.07530
Astrobiology

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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