Prospects for Biosignature Detection with JWST
Abstract
The James Webb Space Telescope (JWST) may provide the first opportunity to characterize the composition of atmospheres of M dwarf terrestrial planets. Due to the nature of M dwarf host stars' UV spectra, atmospheric biosignatures may build up to higher abundances than for planets orbiting G dwarfs, potentially making them more detectable. Krissansen-Totton et al., (2018) argue that the simultaneous detection of CO2 and CH4 could constitute a disequilibrium biosignature in an anoxic environment. However, whether JWST will have the sensitivity to detect biosignatures from oxygenic photosynthesis, or other plausible metabolisms, remains an open question. To provide a comprehensive exploration of the potential detectability of different types of biosignatures with JWST, we have used coupled 1-D climate-photochemical and radiative transfer models to generate synthetic spectra of simulated planetary environments for TRAPPIST-1 d and e that support a range of different biospheres. We simulate JWST observations for these environments, and identify optimal observing modes, exposure times, and retrieval methods for detecting biosignatures and environmental context. Our modeled environments include Archean-Earth-like environments with either a dominant sulfur- or methane-producing biosphere for clear, cloudy and hazy cases, as well as modern Earth analogs with photosynthetic oxygen-producing biospheres for clear and cloudy cases, and also assess the habitability of these environments. We quantify the detectability of the CO2/CH4 biosignature. We find that other biosignatures, including the ethane signature of sulfur biospheres, and oxygen and ozone for photosynthetic biosignatures, will be extremely challenging to detect with JWST. We also explore the detectability of other possible biosignatures, including methyl chloride, which is predominantly produced by tropical plants on Earth, and could serve as an alternative indicator of oxygenic photosynthesis.
- Publication:
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American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23512603M