The Consequences of Late Accretion Volatile Delivery and Loss Mechanisms on Venus' Evolution
(2022) Europlanet Science Congress 2022 — Location: Granada (18.September.2022)
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- Authors
Dehant, Véronique 
- Abstract
- The evolution of surface conditions on Venus has recently made a return to the forefront of planetary sciences questions. Due to both the striking similarities and the obvious differences between Earth and Venus, understanding Venus might hold some of the keys to how terrestrial planets become habitable, either in our solar system or beyond. The question of the origin and persistence of water at the surface/in the atmosphere of Venus determines, in a large part what the planet's evolutionary path has been. The critical difference between Earth and Venus might even be settled during their primordial evolution. Since no sample of Venus can be studied yet, as would be the case for Earth, we turn on alternative methods of investigation. We track the evolution of volatiles at the surface of the planet during its history, since the end of the magma ocean phase. We compare these scenarios with present-day observation and derive limits on maximum amounts of volatiles in the atmosphere of Venus through time, on volatile exchanges, and on water delivery. We have developed coupled numerical simulations of the evolution of Venus, modeling mechanisms that govern its surface conditions and atmosphere composition. Currently, the simulations include modeling of mantle dynamics, core evolution, volcanism, surface alteration, atmospheric escape (both hydrodynamic and non-thermal), greenhouse effect, and the feedback mechanisms between the interior and the atmosphere of the planet. Focusing on Late Accretion, we have modeled the effects of large meteoritic impacts on long term evolution through three aspects: atmosphere erosion, volatile delivery and mantle dynamics perturbation due to energy transfer. The models are constrained by present-day observation and atmosphere composition, with the requirement that scenarios fit reasonnably the current state of the planet. We produce scenarios that fit present-day conditions and feature both early mobile lid regime (akin to plate tectonics) as well as late episodic lid regime with resurfacing events. However, water outgassing during late evolution could be dampened by high surface pressures. Therefore, it is during the early history of Venus, in particular, that we observe the largest volatile exchanges. That era seems to have large repercussions on long term evolution and present-day state, as it determines volatile inventories and repartition.
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Citations
Gillmann, C., Golabek, G., Raymond, S. N., Schonbachler, M., Tackley, P. J., Dehant, V., & Debaille, V. (2022). The Consequences of Late Accretion Volatile Delivery and Loss Mechanisms on Venus’ Evolution. EPSC Abstracts, 16(EPSC2022-62), 2. https://doi.org/10.5194/epsc2022-62 (Original work published 2022)