Remote Detection of Biological Activity via Circular Polarization of Light
William B. Sparks (STScI)
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 describe a study of the circular polarization spectra of photosynthetic microbial organisms. Given their major importance to astrobiology, the advantages accrued by the adoption of photosynthesis and the natural exposure of photosynthesis to observation, such microbes are plausibly commonplace and amenable to remote sensing. We show that the circular polarization spectra exhibit distinctive features apparently related to the biophysics of photosynthesis. We conclude that circular polarization spectroscopy could provide a powerful remote sensing technique for generic life searches.