For years, scientists have been puzzled about why Earth and Mars have fewer important elements like copper and zinc compared to ancient space rocks called meteorites.
These elements, known as moderately volatile elements (MVEs), are important because they are often found alongside life-essential ingredients like water, carbon, and nitrogen.
Now, a new study has uncovered a surprising clue about how our planet formed.
A team of scientists, led by Assistant Professor Damanveer Grewal from Arizona State University, worked with researchers from Caltech, Rice University, and MIT to investigate this mystery.
Their study, published in Science Advances, challenges long-held beliefs about how Earth and Mars lost these key elements.
For a long time, experts thought that MVEs were lost early in the solar system’s history because they didn’t fully condense when planets were forming, or because they disappeared when small planetary bodies, called planetesimals, melted and separated into layers.
But the new research suggests something very different: many of the earliest planetesimals actually kept their MVEs.
To reach this conclusion, the team studied iron meteorites, which are remnants of the metallic cores of some of the first planetary building blocks in our solar system.
Their findings showed that these ancient planetesimals were much richer in MVEs than scientists expected. This means that the materials that formed Earth and Mars originally had plenty of these elements—but something happened later to make them disappear.
So, what caused the loss of these essential elements? The researchers believe that intense cosmic collisions over millions of years stripped away the MVEs from Earth and Mars. Instead of losing them at the start of their formation, these planets gradually lost their MVEs during violent crashes with other space rocks.
“This discovery changes how we think about planetary formation,” said Grewal. “It shows that Earth and Mars started out with plenty of life-essential elements, but they were lost over time due to massive impacts.”
This new understanding reshapes the story of how our planet got its ingredients for life. It also provides new insights into the early history of the solar system and the forces that shaped the worlds we see today.
