Zinc from primitive asteroids that crashed into Earth billions of years ago played a pivotal role in our planet’s “volatile inventory,” which was crucial for the emergence of life, according to new study findings.
Published in Science Advances, the researchers highlight the significant contribution of these celestial bodies to Earth’s formation and provide new insights into the complex processes that led to the development of habitable conditions on our planet.
Led by a team from Imperial College London and the University of Cambridge, the research focuses on the isotopic composition of zinc in meteorites. By analyzing these isotopes, researchers have traced the origins of Earth’s zinc to two differentiated sources.
First, as Earth was forming billions of years ago, the planet’s accretion of materials spun around in a chaotic soupy mess of rocks and gas forming the basic structure of Earth over tens of millions of years. Called planetesimals, they underwent melting and volatility, and eventually would form about 70% of the Earth’s mass. Oddly enough, this process only contributed to about 10% of Earth’s total zinc content.
“One of the most fundamental questions on the origin of life is where the materials we need for life to evolve came from,” explained Cambridge professor and study author Dr. Rayssa Martins in a statement. “If we can understand how these materials came to be on Earth, it might give us clues to how life originated here, and how it might emerge elsewhere.”
Those life-giving materials came from what scientists call “primitive materials.” These are the unmelted rocks and materials that slammed into Earth in its infancy, and deposited their various materials into the planet’s early “body.”
This finding underscores the critical role of unmelted primitive asteroids in delivering essential volatiles to Earth.
The research team employed advanced isotopic analysis techniques to measure zinc isotopes in 21 meteorites. To model Earth’s zinc isotopic composition, Monte Carlo simulations were conducted. These simulations mixed different meteorite groups in arbitrary proportions to replicate Earth’s zinc composition. The results confirmed that asteroid impacts into the early Earth contributed significantly to the planet’s zinc inventory, despite forming only a small fraction of its mass.
The study’s findings have profound implications for our understanding of how life-supporting conditions developed on Earth. By demonstrating that primitive asteroids were a major source of volatiles like zinc, the research suggests that similar processes could be at play in other planetary systems. This knowledge enhances our understanding of planetary formation and the potential for life elsewhere in the universe.
Primitive asteroids’ contribution to Earth’s volatile inventory is not an isolated phenomenon. Other studies have shown that asteroids delivered essential elements such as water and organic compounds to Earth. For instance, carbonaceous chondrites are believed to have brought water and organic molecules necessary for life. Similarly, isotopic studies on elements like potassium support the idea that both inner and outer Solar System materials contributed to Earth’s development.
“Similar conditions and processes are also likely in other young planetary systems,” said Martins. “The roles these different materials play in supplying volatiles is something we should keep in mind when looking for habitable planets elsewhere.”
MJ Banias covers space, security, and technology with The Debrief. You can email him at mj@thedebrief.org or follow him on Twitter @mjbanias.