Question

Origin of Earth's Water

Liquid water covers approximately $71\%$ of Earth's surface, yet the origin of this water remains a subject of scientific debate. Scientists have proposed two main models to explain how Earth acquired its water.

*Model 1*
Earth's water was delivered during the late stage of planetary accretion by carbonaceous chondrites (meteorites originating from the outer asteroid belt). Carbonaceous chondrites are rich in water and organic compounds. The deuterium-to-hydrogen ($D/H$) ratio of these meteorites is approximately $1.4 \times 10^{-4}$, which closely matches the $D/H$ ratio of Earth’s modern oceans ($1.56 \times 10^{-4}$). Proponents of Model 1 argue that because asteroids formed closer to the Sun, they were more likely to intersect Earth's orbit during its final formation phases.

*Model 2*
Earth's water was delivered during the Late Heavy Bombardment, roughly $3.9$ billion years ago, by icy comets originating from the outer solar system. Comets contain up to $80\%$ water ice. Proponents of Model 2 argue that the extreme gravitational perturbations caused by the migration of giant planets scattered comets inward, resulting in frequent impacts on Earth. Although many comets have $D/H$ ratios of approximately $3.0 \times 10^{-4}$ (twice that of Earth's oceans), proponents argue that a subset of comets from the Kuiper Belt has $D/H$ ratios matching Earth's oceans and that comet impacts delivered the vast majority of Earth's volatile elements.

Based on the provided models, is the following statement true or false?

According to Model 2, gravitational perturbations caused by the migration of giant planets scattered comets inward, leading to frequent impacts that delivered Earth's water.