EPFL - Ecole Polytechnique Fédérale de Lausanne logo.
Sep. 4, 2020
How do you know if a distant planet is home to life? Researchers at EPFL have developed a model that can be used to interpret research results from distant "evidence of life". Explanations.
Image above: A new planet is discovered every two to three days. Image Credits: 123RF / PETER JURIK.
Twenty-five years ago, the scientific world discovered the first exoplanet, a planet that orbiting another sun in the galaxy. Since then, more than 4,300 of them have been spotted. And this is far from final! On average, a new planet is discovered every two to three days and almost 200 are said to be telluric, that is to say composed mainly of rocks like the Earth.
Biosignatures
Even if many other parameters must be added to this one to shelter life, such as the presence of water and the distance from their star, it is precisely on these "hard" objects that scientists have focused their quest. potential traces of life. In this context, the search for biosignatures by spectroscopy (study of the spectrum of a physical phenomenon) will probably become one of the most important methods and themes of astronomy in the coming years.
CHEOPS exoplanet chaser satellite
Numerous programs are thus being developed on the basis of new cutting-edge tools, such as the CHEOPS exoplanet chaser satellite, a project in which the University of Bern is participating, put into orbit in December 2019, or the James-Webb optical telescope, including the launch is scheduled for October 2021.
Start from the unknown
What will be the implications of such research? How to interpret the results? What does it mean if, in the end, only one biosignature is identified? Or what to deduce if none is detected? This is where researchers from the Swiss Federal Institute of Technology in Lausanne (EPFL), in collaboration with a team from the University of Rome Tor Vergata, intervened, by proposing an original model, based on the principle of Bayesian statistics, particularly relevant in the presence of small data samples.
"We all have a hunch that if we find evidence of the existence of life on another planet, that means it is all over the galaxy, but to what extent exactly?" notes Amedeo Balbi, professor of astronomy and astrophysics in the Department of Physics at the Roman University. "In this study, we propose a method that allows you to turn that intuition into statistics, and also to say precisely what these numbers mean in terms of quantity and abundance."
From one world to another
“One of our goals is to know how the assumptions, which attribute a certain degree of credibility to the presence of life outside the Earth, are weighed and compared in light of the new data that will be collected in the coming years ”, describes Claudio Grimaldi, researcher at the Laboratory of Complex Matter Physics at EPFL.
The study was able to determine that, given the small number of planets that will be examined in the near future, and assuming that life is born independently on other planets, the detection of a single biosignature could lead to a initially agnostic observer to conclude with a probability greater than 95% that there would be more than 100,000 inhabited planets in the galaxy, that is to say a greater number than that of pulsars, objects resulting from the explosion of a massive star in end of life. Conversely, the complete absence of biosignatures would in no way make it possible to think that we would be the only living beings and would still leave everything open to the abundance of other forms of life in the Milky Way.
Transfer of life between planets
Scientists add a notion to their analysis: that of panspermia, that is to say the possibility that the distribution of life in space is not the result of independent development, but of the transfer of microscopic organisms. or organic matter, between neighboring planets or over great distances, by comets for example. According to these options, the appearance of life would then be correlated with a factor of distance and the capacities of these different forms of life to resist the throes of transference as well as to adapt to new conditions.
Related article:
Cheops observes its first exoplanets and is ready for science
https://orbiterchspacenews.blogspot.com/2020/04/cheops-observes-its-first-exoplanets.html
Related links:
Tor Vergata University of Rome: https://en.uniroma2.it/
CHEOPS Mission Home Page: https://cheops.unibe.ch/
Ecole Polytechnique Fédérale de Lausanne (EPFL): https://www.epfl.ch/en/
Images (mentioned), Animation (ESA), Text, Credits: EPFL/GHI/ Philippe Kottelat/Orbiter.ch Aerospace/Roland Berga.
Greetings, Orbiter.ch
