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Biosignatures of the Earth: I. Airborne spectropolarimetric detection of photosynthetic life

Patty, C.H.L. and Kühn, J.G. and Lambrev, Petar and Spadaccia, S. and Hoeijmakers, H. Jens (2021) Biosignatures of the Earth: I. Airborne spectropolarimetric detection of photosynthetic life. ASTRONOMY & ASTROPHYSICS, 651. ISSN 0004-6361

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Abstract

Context. Homochirality is a generic and unique property of life on Earth and is considered a universal and agnostic biosignature. Homochirality induces fractional circular polarization in the incident light that it reflects. Because this circularly polarized light can be sensed remotely, it can be one of the most compelling candidate biosignatures in life detection missions. While there are also other sources of circular polarization, these result in spectrally flat signals with lower magnitude. Additionally, circular polarization can be a valuable tool in Earth remote sensing because the circular polarization signal directly relates to vegetation physiology. Aims. While high-quality circular polarization measurements can be obtained in the laboratory and under semi-static conditions in the field, there has been a significant gap to more realistic remote sensing conditions. Methods. In this study, we present sensitive circular spectropolarimetric measurements of various landscape elements taken from a fast-moving helicopter. Results. We demonstrate that during flight, within mere seconds of measurements, we can differentiate (S∕ N > 5) between grass fields, forests, and abiotic urban areas. Importantly, we show that with only nonzero circular polarization as a discriminant, photosynthetic organisms can even be measured in lakes. Conclusions. Circular spectropolarimetry can be a powerful technique to detect life beyond Earth, and we emphasize the potential of utilizing circular spectropolarimetry as a remote sensing tool to characterize and monitor in detail the vegetation physiology and terrain features of Earth itself. © ESO 2021.

Item Type: Article
Additional Information: Physikalisches Institut, Universität Bern, Bern, 3012, Switzerland Center for Space and Habitability, Universität Bern, Bern, 3012, Switzerland Département d'Astronomie, Université de Genève, Versoix, 1290, Switzerland Institute of Plant Biology, Biological Research Centre Szeged, Temesvári krt. 62, Szeged, 6726, Hungary Lund Observatory, Lund University, PO Box 43, Lund, 22100, Sweden Leiden Observatory, Leiden University, PO Box 9513, Leiden, 2300 RA, Netherlands Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, Delft, 2629 HS, Netherlands Université Grenoble Alpes, Cnrs, Ipag, Grenoble, 38000, France Cited By :1 Export Date: 14 January 2022 CODEN: AAEJA
Uncontrolled Keywords: physiology; POLARIZATION; remote sensing; VEGETATION; astrobiology; circular polarization; Earth; Techniques: polarimetric; SPECTROPOLARIMETRY; Photosynthetic organisms; planets and satellites: surfaces; planets and satellites: terrestrial planets; Landscape elements; circularly polarized light; Static conditions; Earth remote sensing; Polarization measurements; Remote sensing tools;
Subjects: Q Science / természettudomány > QB Astronomy, Astrophysics / csillagászat, asztrofizika
Q Science / természettudomány > QH Natural history / természetrajz > QH301 Biology / biológia
SWORD Depositor: MTMT SWORD
Depositing User: MTMT SWORD
Date Deposited: 07 Feb 2022 11:19
Last Modified: 07 Feb 2022 11:19
URI: http://real.mtak.hu/id/eprint/137544

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