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Prebiotic species formation during terrestrial planets late accretion using a neural network approach

Presentation #108.03 in the session Astrobiology and Origins of Life (Oral Presentation)

Published onOct 23, 2023
Prebiotic species formation during terrestrial planets late accretion using a neural network approach

Impacts can form prebiotic species (HCN, NH3, CH4) through the interaction of the impact vapor plume and the background atmosphere of a rocky planet. We extend the results of Zorzi & Schaefer (in prep) by looking at the net effect of multiple impacts during sustained bombardment, to assess the production of prebiotic species during the late accretion stage of terrestrial planets. We use a neural network approach to estimate the post-impact atmospheric composition from the planet and impact initial conditions: those are the pre-impact atmospheric chemical composition, surface density and scale height, the target surface material and the single impact kinetic energies. Once trained, the neural network is able to estimate the atmospheric evolution resulting from ten of thousands of impacts within a short computational time compared to a full hydrodynamic and kinetic solution. The model accounts for: i) the partitioning of H, C, N, O vaporized from the surface upon impact in silicate and gas phases; ii) the change in atmospheric composition due to the shock caused by the plume and the subsequent reactions when plume and atmosphere materials mix. We apply the model to solar system objects. For Earth, Mars and Venus, we retrieve atmospheric compositions from literature and use models for Late Heavy Bombardment (LHB) to assess number, size and velocities of impactors 4.1-3.8 Gyr ago (de Niem et al., 2012). Applied to those conditions, our model will assess the effect of impacts on atmospheric evolution and estimate the amount and type of prebiotic molecules that might be present on these worlds, allowing us to determine whether the necessary, yet perhaps not sufficient, conditions for impact-driven emergence of life were present. Preliminary results will be presented at the meeting.

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