Earth may have had all the elements necessary for life, contrary to theories that they came from meteorites.

For many years, scientists have predicted that many elements essential to life, such as sulfur and nitrogen, arrived on Earth when asteroid-like objects carrying them crashed onto our planet’s surface.

But new research published by our team in Scientists progress suggests that many of these elements, called volatiles, may have existed on Earth from the beginning, when it was a planet.

Volatile materials evaporate more easily than other elements. Common examples include carbon, hydrogen, and nitrogen, although our research has focused on a group called chalcogens. Sulfur, selenium and tellurium are all chalcogens.

Understanding how these volatile elements arrived on Earth helps planetary scientists like us better understand Earth’s geological history and could tell us more about the habitability of terrestrial planets beyond Earth.

The popular “late veneer” theory predicts that the Earth first formed from materials low in volatile substances. According to the theory, after the formation of the Earth’s core, the planet became volatile when volatile-rich bodies from the outer solar system collided with the surface.

These objects made up about half a percent of Earth’s mass. If the late plating theory is correct, then most of the elements that make up life arrived on Earth some time after the formation of the Earth’s core.

But our new research suggests that Earth had all of its volatile elements essential for life early on, when the planet formed. These results challenge the late plating theory and are consistent with another study tracing the origin of water on Earth.

To study the origin of volatile substances on Earth, we used a computational technique called first-principles calculus. This technique describes the behavior of isotopes, which are atoms of an element with a variable number of neutrons. You can think of an element as a family: each atom has the same number of protons, but different isotopic cousins ​​have a different number of neutrons.

Different isotopes behaved slightly differently at each stage of Earth’s formation. And the isotopes left a signature after each formation stage that scientists can use as a sort of fingerprint to track where they were throughout Earth’s formation.

First-principles calculations allowed us to calculate the isotope signatures we would expect to see for different chalcogens, based on how the Earth formed. We ran a few models and compared our isotope predictions for each model with actual measurements of chalcogen isotopes on Earth.

We found that although many volatile substances evaporated during the formation of the Earth, when it was hot and glowing, there are still many more left today. Our results suggest that most of the volatiles on Earth are likely leftovers from the early stage of Earth’s formation.

Although chalcogens are interesting to study, future research should focus on other volatile substances essential for life, such as nitrogen. And further research into how these volatiles behave under extreme conditions could help us learn more about how isotopes behave during each of the growth stages of Earth’s formation.

We also hope to use this approach to see if some exoplanets – planets beyond our solar system – might be habitable for life.

This article is republished from The Conversation under a Creative Commons license. Read the original article.