Earth’s Relationship with Water Might Go Back Further than we Thought

Water is an extremely important component of the Earth and has shaped its surface and interior throughout its 4.5 billion year history. But when did it become a part of Earth’s scenery?

Due to the high-energy collisional nature of planetary accretion, the terrestrial planets were thought to have originated as dry, with water being delivered late by comets and other bodies which form further out in the solar system.

In order to pinpoint the origin of water on Planet Earth, scientists from the Woods Hole Oceanographic Institution looked at the ratio between the two stable isotopes of hydrogen in different rocks. They discovered that rocks from the asteroid ‘4 Vesta’ have the same hydrogen isotope composition as the Earth, indicating a similar water content. The volcanic rocks on ‘4 Vesta’ are some of the earliest rocks to have formed within our solar system.

In addition to hydrogen, carbon and nitrogen signatures have also been compared and suggest that carbonaceous chondrites were likely the common source of water. Carbonaceous chondrites are the most primitive and unaltered meteorites which formed in the same cloud of dust and gas as the sun, well before the planets formed.

The isotope similarities between Earth, Vesta and carbonaceous chondrites suggest that either Earth’s water was delivered extremely early on in solar system or that it was always present in the inner solar system. One key implication is that life on our planet could have started form very early on, it may have even started on the other terrestrial planets before they evolved into their inhabitable states as we see them today.