| |
 |
| Paper: |
Living Worlds Working Group: Surface Biosignatures on Potentially Habitable Exoplanets |
| Monograph: |
10, HWO25 Proceedings Part I: Community Science Case Development Documents |
| Page: |
393 |
| Authors: |
Niki Parenteau; Anna Grace Ulses; Connor Metz; Nancy Y. Kiang; Ligia Coelho; Edward Schwieterman; Jonathan Grone; Giulia Roccetti; Svetlana Berdyugina; Eleonora Alei; Lucas Patty; Emilie Lafleche; Taro Matsuo; Dawn Cardace; Schuyler Borges; Avi Mandel; Kenneth Gordon; Joshua Krissansen-Totton; Giada Arney; Bill Philpot; Jacob Lustig-Yeager; Stephanie Olson; Marc Neveu; José A. Caballero; Yuka Fujii; William Sparks; Ludmila Carone; Mariano Battistuzzi; Daniel Whitt |
| DOI: |
10.26624/ECIN8624 |
| Abstract: |
Surface biosignatures are planetary-scale spectral features resulting from absorption and/or scattering of
radiation by organisms containing photosynthetic and non-photosynthetic pigments. The canonical vegetation
red edge (VRE) is so-called due to the sharp contrast in visible light absorbance by light harvesting pigments
in plant leaves versus their high reflectance in the NIR. This secondary class of biosignatures can be used
to corroborate atmospheric biosignatures by generating multiple lines of evidence to aid in assessing their
biogenicity. Furthermore, surface biopigment features are the only way to detect more primitive forms of
anoxygenic photosynthesis if the more metabolically complex oxygenic photosynthesis never evolved.
Surface biosignatures instrument needs: To detect the reflectance spectra of biological pigments on the
surface of habitable exoplanets under atmospheric compositions that reflect different stages of Earth’s history
(Archean, Proterozoic, and Modern), an SNR 20–40 is needed in the visible to near-infrared wavelength
range (∼500–1100 nm). This is for 15% total pigment coverage on abiotic surfaces under 50% cloud cover.
However, there may be some cases in which lower SNR is required; studies are ongoing.
Coronagraph requirements: (1) The detection of surface biosignatures would be greatly enhanced by
having as many parallel coronagraph channels as possible across the whole wavelength range with no or
minimal gaps between channels. (2) Retrieval studies revealed that restricted wavelength ranges (e.g., 0.4–0.7
µm), such as may be used during initial survey strategies, are not sufficient to deconvolve the biopigment
features from the abiotic background. |
|
|
|
|
|
