Imaging & Spectroscopy

There’s More To Life Than O2: Simulating the Detectability Of A Range Of Molecules For Ground-based high-resolution Spectroscopy Of Transiting Terrestrial Exoplanets

By Keith Cowing
April 24, 2023
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There’s More To Life Than O2: Simulating the Detectability Of A Range Of Molecules For Ground-based high-resolution Spectroscopy Of Transiting Terrestrial Exoplanets
Mixing ratios for the major species in the Archean Earth-like (ARE) atmospheres and temperature profiles. Each line represents a self-consistent Earth-like atmosphere orbiting a stellar host. Earlier-type M dwarf hosts are lighter and later-type M dwarf hosts are darker. The dashed blue line represents profiles for the Earth orbiting the Sun for comparison. — astro-ph.EP

Within the next decade, atmospheric O2 on Earth-like M dwarf planets may be accessible with visible–near-infrared, high spectral resolution extremely large ground-based telescope (ELT) instruments.

However, the prospects for using ELTs to detect environmental properties that provide context for O2 have not been thoroughly explored. Additional molecules may help indicate planetary habitability, rule out abiotically generated O2, or reveal alternative biosignatures. To understand the accessibility of environmental context using ELT spectra, we simulate high-resolution transit transmission spectra of previously-generated evolved terrestrial atmospheres.

We consider inhabited pre-industrial and Archean Earth-like atmospheres, and lifeless worlds with abiotic O2 buildup from CO2 and H2O photolysis. All atmospheres are self-consistent with M2V–M8V dwarf host stars. Our simulations include explicit treatment of systematic and telluric effects to model high-resolution spectra for GMT, TMT, and E-ELT configurations for systems 5 and 12 pc from Earth.

Using the cross-correlation technique, we determine the detectability of major species in these atmospheres: O2, O3, CH4, CO2, CO, H2O, and C2H6. Our results suggest that CH4 and CO2 are the most accessible molecules for terrestrial planets transiting a range of M dwarf hosts using an E-ELT, TMT, or GMT sized telescope, and that the O2 NIR and H2O 0.9 μm bands may also be accessible with more observation time.

Overview of methods pipeline. The red round boxes represent the start and end points of the pipeline. The solid green boxes represent models or software pipelines, the white parallelograms represent input or output data products, and the rhombuses represent user-specified metadata or parameters. Cartoon examples of the data products are shown next to each data product node. — astro-ph.EP

Although this technique still faces considerable challenges, the ELTs will provide access to the atmospheres of terrestrial planets transiting earlier-type M-dwarf hosts that may not be possible using JWST.

Miles H. Currie, Victoria S. Meadows, Kaitlin C. Rasmussen

Comments: Accepted for publication in The Planetary Science Journal
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2304.10683 [astro-ph.EP] (or arXiv:2304.10683v1 [astro-ph.EP] for this version)
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Submission history
From: Miles Currie
[v1] Fri, 21 Apr 2023 00:18:59 UTC (4,055 KB)

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) 🖖🏻