Origin of Water in the Terrestrial Planets: Insights from Meteorite Data and Planet Formation Models

TL;DR

This paper explores the origin of water in terrestrial planets, emphasizing that it primarily came from inner disk materials and water-rich planetesimals from beyond the snowline, rather than from in-situ condensation.

Contribution

It provides new insights into the sources and delivery mechanisms of water to terrestrial planets based on meteorite data and planet formation models.

Findings

Water in terrestrial planets mainly derived from inner disk materials.

Water-rich planetesimals from beyond the snowline contributed significantly.

Limited mixing occurred between inner and outer Solar System materials.

Abstract

Water condensed as ice beyond the water snowline, the location in the Sun's natal gaseous disk where temperatures were below 170 K. As the disk evolved and cooled, the snowline moved inwards. A low temperature in the terrestrial planet-forming region is unlikely to be the origin of water on the planets, and the distinct isotopic compositions of planetary objects formed in the inner and outer disks suggest limited early mixing of inner and outer Solar System materials. Water in our terrestrial planets has rather been derived from H-bearing materials indigenous to the inner disk and delivered by water-rich planetesimals formed beyond the snowline and scattered inwards during the growth, migration, and dynamical evolution of the giant planets.