An international team of scientists led by researchers from the University of Bern in Switzerland has discovered the main distinguishing feature of living matter from a bird’s eye view. The results of the study will help to develop methods for finding traces of extraterrestrial life on other planets from a distance. This is reported in an article published in the journal Astronomy & Astrophysics.
It is a circular polarization of electromagnetic radiation reflected from biological matter, when the direction of the electric field vector moves in a circle perpendicular to the direction of wave propagation. This phenomenon is caused by homochirality, when biological molecules are represented by only one of two chirality variants, i.e. they have either L- or D-configuration. Both configurations are mirror images of each other, and molecules with this property are called enantiomers. Homochirality is explained by the fact that enantiomers are characterized by different biochemical activities, and cannot be equal for a living organism.
Scientists have learned to detect circular polarization generated by homochirality from a height of two kilometers using the FlyPol spectropolarimeter on board a helicopter moving at a speed of 70 kilometers per hour. The advanced instrument consists of a camera equipped with special lenses and receivers that can separate the circular polarization from the rest of the light. The setup allows detection of algae biosignatures in water bodies.
In the future, researchers plan to test the method aboard the International Space Station. In the future, the method could be used to search for life in the solar system and beyond.