Once you get beyond the “where do we look for life” part of the question, the next piece is “how do we detect that life?”. In what I think is groundbreaking research, a team of scientists used a helicopter flying at 70 kilometers per hour at a distance of two kilometers above the ground to detect signatures of life here on Earth. And they found them. In fact, they were able to tell the difference between fields, forests, and urban areas.

First author Lucas Patty explains: When light is reflected by biological matter, a part of the light’s electromagnetic waves will travel in either clockwise or counterclockwise spirals. This phenomenon is called circular polarization and is caused by the biological matter’s homochirality. Similar spirals of light are not produced by abiotic non-living nature.

A note about the term homochirality: chirality is the property of handedness — left-handed or right-handed. We use this term in biology, and particularly in molecular biology, to describe the way molecules, like that of DNA, occur. Except, unlike hands, in molecules, the handedness is either left or right not paired. And that handedness, or chirality, can be used as a biosignature.

And this team found that signature from a moving helicopter. Now we can use their technology to engineer systems that could be on spacecraft, and first up, they’re working on adapting it for the International Space Station (ISS). I’m excited to follow where this research goes.

More Information

University of Bern press release

“Biosignatures of the Earth I. Airborne spectropolarimetric detection of photosynthetic life,” C. H. L. Patty et al., to be published in Astronomy & Astrophysics (preprint on arxiv.org)