Detection of circular polarization in light scattered from photosynthetic microbes.
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. Because of 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.
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA. sparks@stsci.edu
William B
WB
Sparks
James
J
Hough
Thomas A
TA
Germer
Feng
F
Chen
Shiladitya
S
DasSarma
Priya
P
DasSarma
Frank T
FT
Robb
Nadine
N
Manset
Ludmilla
L
Kolokolova
Neill
N
Reid
F Duccio
FD
Macchetto
William
W
Martin
D001419:Bacteria / Q000378:metabolism; D002734:Chlorophyll / Q000737:chemistry; D004867:Equipment Design; D018559:Exobiology / Q000295:instrumentation* / Q000379:methods; D005118:Extraterrestrial Environment; D008027:Light; D055095:Optics and Photonics; D010788:Photosynthesis; D018515:Plant Leaves / Q000378:metabolism; D012031:Refractometry; D012542:Scattering, Radiation; D046940:Synechococcus / Q000378:metabolism
D002734:Chlorophyll