A late veneer explanation for the 3 to 4 ppm Δ17O Earth-Moon difference implies that a large fraction of Earth’s water was delivered earlier than the giant impact event. Lunar whole rock and mineral separates analyzed in this study include samples from all the Apollo landings: Apollo 11 (10020 and 10044), Apollo 12 (12016 and 12040), Apollo 14 (14053), Apollo 15 (15016, 15059, 15386, and 15555), Apollo 16 (62237 and 67435), and Apollo 17 (70017, 70035, 71055, 72155, and 78235). If the impactor had a different oxygen isotopic composition (Δ17O) to the proto-Earth, a prediction of this model is that Earth and the Moon should display resolvable isotopic differences (see Results for the definition of Δ17O) (2, 3). If the Earth-Moon system evolved from an initially highly vaporized and isotopically homogenized state, as indicated by recent dynamical models, then the terrestrial basalt-lunar oxygen isotope difference detected by our study may be a reflection of post–giant impact additions to Earth. The collision that created the moon must have been so powerful that it caused the material of the young Earth and the large body that hit it to completely blend, new research suggests — and water must have already been on the surface of Earth before the moon-forming crash. On the basis of this assumption, our data indicate that post–giant impact additions to Earth could have contributed between 5 and 30% of Earth's water, depending on global water estimates. “Exoplanets with water on their surfaces may be much more common than we previously thought. "Because water is such a vital ingredient for life, we rightly see it as precious. Journal reference: Science Advances, DOI: 10.1126/sciadv.aao5928

Read more: The moon may have formed in a vaporised, doughnut-shaped Earth
Research published in the journal Science Advances implies the Earth may have had water earlier than thought, and that terrestrial water could have survived the impact that created the Moon, the event which was previously hypothesised to be responsible for our planet's water.