Earth’s water may have been inherited from material similar to enstatite chondrite meteorites

TLDR

The origin of Earth's water remains unclear; although enstatite chondrites share isotopic signatures with terrestrial rocks, they are presumed dry, so water is usually attributed to late accretion of hydrated outer Solar System materials. We show that enstatite chondrites contain enough hydrogen to deliver at least three times the ocean mass, and their hydrogen and nitrogen isotopic compositions match Earth's mantle, indicating EC‑like asteroids could have supplied Earth's volatiles.

Abstract

The origin of Earth's water remains unknown. Enstatite chondrite (EC) meteorites have similar isotopic composition to terrestrial rocks and thus may be representative of the material that formed Earth. ECs are presumed to be devoid of water because they formed in the inner Solar System. Earth's water is therefore generally attributed to the late addition of a small fraction of hydrated materials, such as carbonaceous chondrite meteorites, which originated in the outer Solar System where water was more abundant. We show that EC meteorites contain sufficient hydrogen to have delivered to Earth at least three times the mass of water in its oceans. EC hydrogen and nitrogen isotopic compositions match those of Earth's mantle, so EC-like asteroids might have contributed these volatile elements to Earth's crust and mantle.