This could be an important step on the road to discovering life on other planets: scientists led by the University of Bern and the National Center for Competence in Research (NCCR) PlanetS are discovering a key molecular property of all living things from a helicopter flying several kilometers above the Earth’s surface. Measurement technology could also open up opportunities for remote sensing of the Earth.
Left hand and right hand are almost identical images of each other. But no matter how twisted and twisted, layers cannot be layered on top of each other. This is why the left glove does not fit the right hand as well as the left. In science, this property is called chirality.
Just as hands are helical, molecules can also be helical. In fact, most molecules in the cells of living organisms, such as DNA, are chiral molecules. Unlike hands, which usually come in left and right pairs, the particles of life occur almost exclusively in their “left” or “right” version. They are the same, the researchers say. Why this is, is still not clear. But this molecular analogue is a defining characteristic of life, called a biosignature.
As part of the MERMOZ project (see box below), an international team led by the University of Bern and the National Center for Efficiency in PRN PlanetS Research succeeded in detecting this signature at a distance of two kilometers and a speed of 70 km/h. “The big advance is that these measurements were made in a platform that moves and vibrates, and we are still detecting these vital fingerprints in a matter of seconds,” says Jonas Kuhn, MERMOZ Project Director at the University of Bern and co-author of the study just published in the Journal of Astronomy and Astrophysics.
A tool that recognizes living matter
“When light is reflected from a biological material, some of the electromagnetic waves in the light will travel clockwise or counterclockwise. This phenomenon is called circular polarization and is caused by the symmetry of biological matter. Lead study author Lucas Baty, a MERMOZ postdoctoral researcher at the University of Bern and a member of PRN PlanetS, explains that similar light helixes are not produced by abiotic, nonliving nature.
However, measuring this circular polarization is difficult. The signal is very weak and usually accounts for less than one percent of the light reflected. To measure this, the team developed a dedicated device called a spectrometer. It consists of a camera with special lenses and receivers capable of separating the circular polarization from the rest of the light.
However, even with this elaborate device, new results were impossible until recently. “Barely 4 years ago, we could only detect the signal from a very close distance, about 20 cm, so we had to monitor the same place for several minutes,” Lucas Baty recalls. But the improvements he and his colleagues have made to the instrument allow for faster and more stable detection, and the strength of the circularly polarized signature persists even with distance. This made the device suitable for the first atmospheric measurements of circular polarization.
Useful measurements on Earth and in space
Using this improved tool, called FlyPol, they showed that in just seconds they could distinguish grassy fields, forests and urban areas from a fast-moving helicopter. Measurements readily show that living matter shows distinct polarization signals, while methods, for example, do not show significant circular polarization signals. With the current setup, they can even detect signals from algae in lakes.
After their successful tests, the scientists are now looking to go even further. “The next step we hope to take is to make similar discoveries from the International Space Station (ISS), looking at Earth. This will allow us to assess the possibility of detecting biometrics on a planetary scale. This step will be critical to allow the search for life in and out of our solar system using polarization,” says lead researcher and MERMOZ co-author, Brice-Olivier Demory, professor of astrophysics at the university. from Bern and a member of PRN Planets.
Sensitive observation of these circularly polarized signals is not only important for future life-detecting tasks. Lucas Bate explains: “Because the signal is directly related to the molecular makeup of life and thus to its functions, it can also provide valuable additional information in Earth remote sensing. For example, it can provide information on deforestation or plant diseases. It would even be possible to implement circular polarization in monitoring toxic algal blooms and coral reefs and the effects of acidification on them.
SAINT-EX – Research and Characterization of Exoplanets
The SAINT-EX research group (funded by the SNF Chair Prof. Press-Olivier Demory) focuses on:
- Detection of temperate Earth-sized exoplanets (SAINT-EX Observatory),
- remote sensing of life in the atmosphere/planetary surfaces (MERMOS),
- Devices for the diagnosis and staging of non-invasive cancer in vivo (BrainPol).
The MERMOZ (Observation of Surface Features with Modern Polar Characteristics) project aims to determine if we can identify and characterize life on Earth from space, by building a reference library of surface feature signatures using the Stokes polarimetric spectrometer. In this context, our planet is considered a proxy for the other outer bodies and planets of the solar system.
MERMOZ is a joint project of the Universities of Bern, Leiden and Delft (Netherlands).
The feasibility study for the project is being funded by the Center for Space and Habitat (CSH) and PRN PlanetS.
PRN PlanetS: Finding a Planet Made in Switzerland
In 2014, the Swiss National Science Foundation awarded the University of Bern the National Research Center (PRN) PlanetS, which it jointly runs with the University of Geneva.
Since its participation in the first moon landing in 1969, the University of Bern has participated in the space missions of major space organizations, such as ESA, NASA, ROSCOSMOS and JAXA. He currently co-leads the European Space Agency (ESA) CHEOPS mission with the University of Geneva. In addition, Berne researchers are among the world’s leaders in models and simulations of planet formation and development.
With the discovery of the first exoplanet, the University of Geneva has established itself as one of the leading institutions in this field. This led, for example, to the construction and installation of the HARPS spectrometer on the ESO 3.6-meter telescope at La Silla in 2003 under the supervision of Geneva. This was followed by the ESPRESSO instrument on the ESO VLT telescope in Paranal. The CHEOPS Scientific Operations Center is also located in Geneva.
ETH Zurich and the University of Zurich are PRN PlanetS partner institutions. Scientists from the fields of astrophysics, data processing, and Earth sciences lead projects and make important research contributions to PRN PlanetS. In addition, ETH is a world leader in instrumentation for various observatories and space missions.
PRN PlanetS is organized around the following research themes:
- Early stages of planet formation
- Planetary systems engineering, formation and evolution
- Atmospheres, surfaces and interiors of the planets
- Determine habitability of planets.
Space exploration in Bern: with the world’s elite since the first moon landing
When the second man, “Buzz” Aldrin, emerged from the lunar module on July 21, 1969, his first task was to set up the Bernese Solar Wind Composition (SWC) experiment also known as the “solar wind sail” by planting it in lunar soil, even before the American flag . This experiment, which was planned and the results of which were analyzed by Professor Dr Johannes Gess and his team from the University of Bern’s Institute of Physics, was the first major event in the history of the University of Bern. Space exploration in Bern.
Since then, space exploration in Berne has been among the world’s elite. The University of Bern has participated in the space missions of major space organizations, such as ESA, NASA, ROSCOSMOS and JAXA. He currently co-leads the European Space Agency (ESA) CHEOPS mission with the University of Geneva. In addition, Berne researchers are among the world’s leaders in models and simulations of planet formation and development.
The successful work of the Department of Space Research and Planetary Science (WP) of the Institute of Physics at the University of Bern has been reinforced by the establishment of a university center of competence, the Center for Space and Habitability (CSH). The Swiss National Science Foundation also awarded the University of Bern the National Research Center (PRN) PlanetS, which it operates with the University of Geneva.
Reference: “Biological Footprints of Earth I. Airborne Tropical Spectroscopic Detection of Phototrophic Life” by CHL Patty, J. G. Kuhn, P. H. Lambrev, S. Spadaccia, H. J. Hoeijmakers, C. Keller, W. Mulder, V. Pallichadath, O. Poch, F Snik and D. M. Stam, A. Pommerol, and B. O. Demory, Accepted, Astronomy and astrophysics.
DOI: 10.1051 / 0004-6361 / 202140845