Detection of circular polarization in light scattered from photosynthetic microbes

TL;DR

This study demonstrates that circular polarization in scattered light from photosynthetic microbes can serve as a universal biosignature for remote life detection, leveraging optical activity of chiral molecules.

Contribution

It provides the first detection of circular polarization from microbes and links it to their biochemical properties, proposing a new remote sensing method for life detection.

Findings

Circular polarization detected in light scattered from microbes.

Circular polarization linked to photosynthetic absorption bands.

Potential for circular polarization spectroscopy in astrobiology.

Abstract

The identification of a universal biosignature that could be sensed remotely is critical to the prospects for success in the search for life elsewhere in the universe. A candidate universal biosignature is homochirality, which is likely to be a generic property of all biochemical life. Due to the optical activity of chiral molecules, it has been hypothesized that this unique characteristic may provide a suitable remote sensing probe using circular polarization spectroscopy. Here, we report the detection of circular polarization in light scattered by photosynthetic microbes. We show that the circular polarization appears to arise from circular dichroism of the strong electronic transitions of photosynthetic absorption bands. We conclude that circular polarization spectroscopy could provide a powerful remote sensing technique for generic life searches.