Biomarkers in extra-solar systems

Detecting life beyond the solar system present an additional challenge because our investigation capabilities are even more limited, restricted to low signal-to-noise remote sensing. However, unlike the solar system, we have the opportunity to study a very large sample of stars on which we could potentially search for life.

A challenge will be to characterize a fraction of these planets with the most advanced telescopes (JWST/NASA launch in 2018 and ELT/ESO) in an attempt to characterize their atmosphere and to search for biomarkers. It is supposed here that biological activity can change a planet’s environment as it did for Earth with the advent of oxygenic photosynthesis. As stated by Selsis (2015, Pathways Towards Habitable Planets) “the most general way to search for signs of life may be to search for a strong thermodynamic disequilibrium in the atmosphere, which cannot be maintained by abiological processes only”.

We will focus our atmospheric characterization work on planets around M-dwarfs whose atmospheres will be amenable to characterization in the coming decade. The breakthroughs in instrumentation and analysis methods, as well as the recent detection of potentially habitable exoplanets around the closest stars, that are ideal targets, open the prospect of detecting the molecules in the atmospheres of habitable exoplanets. We are currently participating to the study of the SPHERE instrument upgrade, with the main objective of characterizing the atmosphere of the closest habitable exoplanet, Proxima b and we are participating to a collaboration to obtain spectral constraints of telluric planets atmosphere through observations with JWST/NASA.