If there is life on other planets, how can we stand a reasonable chance of detecting it? A new technological advance may provide the basis for such analysis. This is based on the detection of a specific molecular property associated with all living organisms.
To make the assessment, relatively close range is required. The trials to date involve a helicopter flying only a few kilometers above ground. Nonetheless, should the technology be equipped to a space craft or space-to-planet drone, then it may assist in scanning for signs of life on reachable planets.
The technology comes from the University of Bern and of the National Centre of Competence in Research (NCCR). The detection process is based on chirality, a principle that however something is twisted and turned it cannot be superimposed onto something else. Ana analogy is with why a left glove will not fit onto the right hand.
Most molecules in the cells of living organisms are chiral, or, more accurately, homochiral and these produce a biosignature. The researchers have succeeded in detecting this signature from a distance of 2 kilometers from a craft moving at a velocity of 70 kilometers per hour, a platform that was not only moving but also vibrating. The detection occurred in a matter of seconds.
The instrumentation works as light is reflected by biological matter. As this occurs, part of the light’s electromagnetic waves travel in either clockwise or counterclockwise spirals (or circular polarization) and this is the product of biological matter’s homochirality. The same types of spirals of light do not occur with matter that is non-living and non-biological.
These signals are faint and they make up less than one percent of the light that is reflected. Accurate detection requires a device called a spectropolarimeter, formed of a camera and special lenses and receivers.
The new instrument has been named FlyPol, and trials show it can rapidly differentiate between grass fields, forests and urban areas. In addition, a ‘non-living’ area like a road produces no signal. Further trials have shown how the instrument can detect algae in lakes.
For the next trial, the scientists aim to test out the instrument from the International Space Station, with the instrument directed at Earth. This is the step towards assessing the detectability of planetary-scale biosignatures.
The research is titled “Biosignatures of the Earth I. Airborne spectropolarimetric detection of photosynthetic life”, and it appears in the journal Astronomy & Astrophysics.
