Astrochemical Inheritance of Terrestrial Planets Water from Local Wet Silicates
Lise Boitard-Crépeau, Stefano Pantaleone, Cecilia Ceccarelli, Pierre Beck, Lydie Bonal + 1 more
TLDR
This paper proposes that terrestrial planets acquired their water from local wet silicates, challenging the need for outer Solar System delivery.
Key contributions
- New quantum mechanics calculations show water binds twice as strongly to silicate grains than amorphous ice.
- Stronger water binding to silicates enables retention at higher temperatures, providing a local source for inner planets.
- Model predictions align with observed water content in terrestrial planets, suggesting a local origin for their water.
Why it matters
This research offers a compelling alternative to the prevailing theory of water delivery from the outer Solar System. It suggests that Earth and other inner planets could have formed with their water locally present, fundamentally changing our understanding of planetary formation and habitability.
Original Abstract
The delivery of water to the inner Solar System rocky planets, including Earth, remains debated, as standard models assume that they formed from dry grains, inside the snowline of the protosolar nebula. However, a recent work showed that a not-negligible amount of water formed during the prestellar phase could have been retained by pebbles and planetesimals at the Earth's orbit in enough quantities to reproduce its water content. This study was based based on quantum mechanics (QM) calculations of the binding energy (BE) of water on amorphous ice and on a kinetic approach. Here, we present new QM calculations of the BE of water frozen on the surface of silicate grains, and show that it is on average about twice larger than that on the amorphous ice. The contribution of this first layer of frozen water increases the dust temperature at which frozen water can be retained. This provides a local source of water not only for the Earth, but also for the inner rocky planets. The predictions from our model are in agreement with the available estimates of water content in terrestrial planets. This suggests that water delivery from the outer Solar System may not be required.
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