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Detecting Fundamental Chiral Biosignatures in the Ultraviolet Polarization Spectrum.
William B Sparks1, Thomas A Germer2, Frank T Robb3
1SETI Institute, Mountain View, California, USA.
Astrobiology
|April 25, 2026
Summary
Chiral molecules, essential for life, exhibit unique ultraviolet (UV) circular polarization signatures. These biosignatures, detectable in microbes, persist even after significant radiation exposure, offering a promising method for astrobiology research.
Area of Science:
- Astrobiology
- Biophysics
- Spectroscopy
Background:
- Life as we know it relies on homochiral molecules (e.g., amino acids, sugars).
- This homochirality is a potential universal biosignature for extraterrestrial life.
- Ultraviolet (UV) circular polarization is a method for detecting molecular chirality.
Purpose of the Study:
- To investigate UV circular polarization signatures of chemoautotrophic microbes.
- To assess the persistence of these chiral signatures under simulated extraterrestrial radiation conditions.
- To evaluate UV circular polarization as a biosignature detection method for astrobiology missions.
Main Methods:
- Transmission spectroscopy was used to measure UV circular polarization of microbial samples.
- Samples were subjected to 10 keV electron irradiation simulating Europan surface conditions.
- Reflection spectropolarimetry was tested for remote sensing applicability.
- A Murchison meteorite sample was used as a control.
Main Results:
- Distinctive UV chiral signatures were observed in chemoautotrophic microbes.
- These signatures correspond to protein secondary structures and other chiral molecules.
- Chiral signatures persisted after significant electron irradiation, dependent on sample properties.
- Remote sensing via reflection spectropolarimetry yielded null results.
Conclusions:
- UV circular polarization spectroscopy can detect generic chiral biosignatures in potential extraterrestrial life.
- The persistence of chiral signatures under radiation is crucial for their detection.
- Further development of remote sensing techniques for chiral detection is needed.
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