Coupling Planetary and Ecosystem Modeling to Asses Habitability and
Inhabitation in the Solar System and beyond

Stephane Mazevet

Observatoire de la Côte d’Azur, University Côte d’Azur, Nice (France)

With thousands of exoplanets now identified, the characterization of habitable planets and the potential
identification of inhabited ones is a major challenge for the coming decades. To address this challenge,
we developed an innovative approach to assess habitability and inhabitation by coupling for the first
time the atmosphere and the interior modeling with the biological activity based on ecosystem modeling.
I will review the results we obtained in four different situations where habitability and inhabitation are in
question. We first applied the method to asses the possibility of methanogenic activity at the Enceladus
ocean floor and provide an interpretation for the plume composition measured by the Cassini mission[1].
Secondly, we quantified the impact of methanogenic activity on the composition of the early Earth
atmosphere and its influence on the long term climate[2]. Thirdly, we considered Early Mars to asses
favorable landing sites to investigate whether methanogenesis started 4 billion years ago[3]. Lastly, we
applied the method to habitable Earth-like planets around G-type stars to inform the design of future
space missions[4].
[1] A. Affholder, F. Guyot, B. Sauterey, R. Ferrière, S. Mazevet, “Bayesian analysis of Enceladus’s plume data to assess
methanogenesis”, Nature Astronomy 5 (2021), p. 805-814.
[2] B. Sauterey, B. Charnay, A. Affholder, S. Mazevet, R.F errière,“Co-evolution of primitive methane-cycling ecosystems and
early Earth’s atmosphere and climate”, Nature Communications 11 (2020).
[3] B. Sauterey, B. Charnay, A. Affholder, S. Mazevet, R. Ferrière,“Early Mars habitability and global cooling by H2-based
methanogens”, Nature Astronomy (2022).
[4] S. Mazevet, A. Affholder, B. Sauterey, A. Bixel, D. Apai and R. Ferriere « Prospects for the characterization of habitable
planets », Comptes rendus de l’académie des sciences, physique, pp. 1-16. doi : 10.5802/crphys.154. (2023)