2018/01/01 by Edward W. Schwieterman
Earth and Planetary Sciences · Environmental Science · Physics and Astronomy · #Abiotic component #Astro and Planetary Science #Astrobiology #Astronomy #Biosphere #Environmental science #Exoplanet #Geology #Isotope Analysis in Ecology #Marine and coastal plant biology #Paleontology #Physics #Planet #Planetary habitability #astro-ph.EP
paper · pdf · doi:10.1007/978-3-319-55333-7_69
26 pages, 9 figures, review to appear in Handbook of Exoplanets. Fixed figure conversion errors
openalex publication_date 2018/01/01 · arxiv created 2018/03/15 · arxiv updated 2018/12/05 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Recent discoveries of potentially habitable exoplanets have ignited the prospect of spectroscopic investigations of exoplanet surfaces and atmospheres for signs of life. This chapter provides an overview of potential surface and temporal exoplanet biosignatures, reviewing Earth analogues and proposed applications based on observations and models. The vegetation red-edge (VRE) remains the most well-studied surface biosignature. Extensions of the VRE, spectral "edges" produced in part by photosynthetic or nonphotosynthetic pigments, may likewise present potential evidence of life. Polarization signatures have the capacity to discriminate between biotic and abiotic "edge" features in the face of false positives from band-gap generating material. Temporal biosignatures -- modulations in measurable quantities such as gas abundances (e.g., CO2), surface features, or emission of light (e.g., fluorescence, bioluminescence) that can be directly linked to the actions of a biosphere -- are in general less well studied than surface or gaseous biosignatures. However, remote observations of Earth's biosphere nonetheless provide proofs of concept for these techniques and are reviewed here. Surface and temporal biosignatures provide complementary information to gaseous biosignatures, and while likely more challenging to observe, would contribute information inaccessible from study of the time-averaged atmospheric composition alone.