A race against the clock: Constraining the timing of cometary bombardment relative to Earth's growth
arXiv:2309.03954 · doi:10.1016/j.icarus.2023.115754
Abstract
Comets are considered a potential source of inner solar system volatiles, but the timing of this delivery relative to that of Earth's accretion is still poorly understood. Measurements of xenon isotopes in comet 67P/Churyumov-Gerasimenko revealed that comets partly contributed to the Earth's atmosphere. However, there is no conclusive evidence of a significant cometary component in the Earth's mantle. These geochemical constraints would favour a contribution of comets mainly occurring after the last stages of Earth's formation. Here, we evaluate whether dynamical simulations satisfy these constraints in the context of an Early Instability model. We perform dynamical simulations of the solar system, calculate the probability of collision between comets and Earth analogs component embryos through time and estimate the total cometary mass accreted in Earth analogs as a function of time. While our results are in excellent agreement with geochemical constraints, we also demonstrate that the contribution of comets on Earth might have been delayed with respect to the timing of the instability, due to a stochastic component of the bombardment. More importantly, we show that it is possible that enough cometary mass has been brought to Earth after it had finished forming so that the xenon constraint is not necessarily in conflict with an Early Instability scenario. However, it appears very likely that a few comets were delivered to Earth early in its accretion history, thus contributing to the mantle's budget. Finally, we compare the delivery of cometary material on Earth to Venus and Mars. These results emphasize the stochastic nature of the cometary bombardment in the inner solar system.
26 pages, 12 figures
References in corpus (24)
- Dynamics of the giant planets of the solar system in the gaseous proto-planetary disk and relationship to the current orbital architecture
- Water Delivery and Giant Impacts in the 'Grand Tack' Scenario
- Formation of planetary systems by pebble accretion and migration: How the radial pebble flux determines a terrestrial-planet or super-Earth growth mode
- The timeline of the Lunar bombardment - revisited
- Highly Siderophile Elements in the Earth's Mantle as a Clock for the Moon-forming Impact
- Constraints on resonant-trapping for two planets embedded in a protoplanetary disc
- Origin and Evolution of Short-Period Comets
- Contemporary formation of early solar system planetesimals at two distinct radial locations
- Planetesimal rings as the cause of the Solar System's planetary architecture
- Dynamical evidence for an early giant planet instability
- The Feeding Zones of Terrestrial Planets and Insights into Moon Formation
- Constraining the giant planets' initial configuration from their evolution: implications for the timing of the planetary instability
- Outward migration of Jupiter and Saturn in 3:2 or 2:1 resonance in radiative disks: implications for the Grand Tack and Nice models
- Early Solar System instability triggered by dispersal of the gaseous disk
- The Role of Early Giant Planet Instability in the Terrestrial Planet Formation
- Terrestrial Planet Formation from an Annulus
- A re-assessment of the Kuiper belt size distribution for sub-kilometer objects, revealing collisional equilibrium at small sizes
- Early Bombardment of the Moon: Connecting the Lunar Crater Record to the Terrestrial Planet Formation
- Thermal processing of Jupiter Family Comets during their chaotic orbital evolution
- Fate of the runner in hit-and-run collisions
- Collision Chains among the Terrestrial Planets. II. An Asymmetry between Earth and Venus
- Effects of pebble accretion on the growth and composition of planetesimals in the inner Solar System
- Rethinking the role of the giant planet instability in terrestrial planet formation models
- Building Terrestrial Planets: Why results of perfect-merging simulations are not quantitatively reliable approximations to accurate modeling of terrestrial planet formation