Late veneer on the terrestrial planets: dynamics perspective

The origin of the late veneer of the terrestrial planets and of the lunar bombardment has been the subject of numerous studies in the field of cosmochemistry and in the field of planet formation and dynamical evolution of the early solar system. In the last years, we have studied [1,..,5] the dynamical and collisional evolution of the population of planetesimals originally in the terrestrial planet region and still “alive” at the time of the Moon-forming event. We have shown that this population of leftover planetesimals can explain the late veneer of Earth, Mars and Vesta as constrained by the amount of highly siderophile elements (HSE) in their mantles as well as the number of late impact basins on the Moon. The low concentration of HSE in the lunar mantle can be explained by a late sequestration of lunar mantle HSEs into the core at the time of the lunar mantle overturn. The origin of the late veneer carrier from the terrestrial planet region is consistent with the isotopic constraints on the source of the late veneer, indicating a non-carbonaceous source. This suggests that the carbonaceous projectiles that delivered part of the terrestrial volatile elements had already decayed by the time the late veneer started.

[5]Nesvorný, D., et al. 2023, Icarus, 399, 115545.

[4]Nesvorný, D., et al. 2022, ApJL, 941, L9.

[3]Zhu, M.-H. et al. 2021, Nature Astronomy, 5, 1286.

[2]Zhu, M.-H. et al. 2019, Nature Astronomy, 571, 226.

[1]Morbidelli, A., et al. 2018, Icarus, 305, 262.