The early Earth’s reservoir of exogenous organic matter and its relevance to the emergence of prebiotic chemical systems

Grégoire Danger – PIIM, Marseille

Some of the organic matter in our solar system may have originated in dense molecular clouds. These clouds are made up of silicate grains surrounded by ices including H₂O, CO₂, CO, CH₃OH and NH₃. In some areas, the cloud will collapse on itself to form a solar nebula that will potentially evolve into a planetary system such as our solar system. During this evolution, these ices will undergo numerous modifications leading to a complexification of the organic matrix. The agglomeration of these grains carrying more or less evolved organic matter have formed the small bodies of our solar system, from the asteroids to the comets far away. These small objects could have then served as a reservoir of organic matter for the development of prebiotic chemistry on the surface of a telluric planet such as the primitive Earth.

Using experimental approaches developed in our laboratory, we try to reproduce the conditions of formation of interstellar grains and to study their molecular composition. Following this strategy, we aim to determine the role of solid phases in the origin and evolution of organic matter (volatile and non-volatile) in these astrophysical environments. Linked to the question of the origin of biochemical systems on Earth, our research could help determine how such organic matter may have serve in the emergence of prebiotic chemical processes, representing the first stages towards the appearance of life.