Researchers from Switzerland may have succeeded in reaching a milestone on the way to a new type of evidence of extraterrestrial life. For the first time, they have succeeded in measuring a central molecular property from several kilometers away that distinguishes living beings from non-living matter. The method could soon be used to analyze terrestrial biosignatures from the International Space Station (ISS) before measurements from sources inside and outside the solar system become possible. Research would then have another avenue to look for extraterrestrial life.
Molecules of life never exist as mirror images
As the team led by Lucas Patty from the University of Bern now explains, their method deals with a property of molecules called chirality. This refers to whether molecules, depending on the spatial arrangement of the atoms they contain, can be mapped congruently to one another or whether they are mirror-inverted like human hands, among other things. While molecules usually appear in both orientations, the building blocks of life are almost exclusively “homochiral”, explain it. In other words, they only appear in one orientation – in some cases the corresponding mirror images (the “enantiomers”) are even toxic. Why this is so is still unclear, says the team. It is still useful, as a possible bio-signature.
For the first time it has now been possible to measure this signature from a great distance and at high speed, namely from a height of two kilometers at 70 kilometers per hour from a helicopter: “The significant advance is that these measurements were carried out on a platform, that moved and vibrated, and that we were still able to detect these biosignatures within seconds, “explains co-author Jonas Kühn. Like the team now explained in the journal Astronomy and Astrophysics, it relied on a phenomenon called circular polarization. Four years ago, it was only able to demonstrate homochirality from a distance of 20 centimeters.
Next, the team is planning an instrument that will be used to provide evidence from the ISS. In doing so, it could help find deforestation and plant diseases. But above all, this step will be decisive in order to clarify whether traces of life can also be found on other celestial bodies with the method.