Biosignatures of the Earth I. Airborne spectropolarimetric detection of photosynthetic life
A&A 651, A68 (2021) 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 sens...
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Main Authors: | , , , , , , , , , , , , |
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Format: | Journal Article |
Language: | English |
Published: |
01-06-2021
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Subjects: | |
Online Access: | Get full text |
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Summary: | A&A 651, A68 (2021) 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. |
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DOI: | 10.48550/arxiv.2106.00493 |