Scientists have uncovered a groundbreaking revelation about the origins of life-sustaining elements on Earth. By analyzing the unique chemical signatures of zinc in meteorites, researchers have unveiled a crucial link between the presence of volatile compounds and the emergence of life as we know it.
Volatile elements and compounds, which readily transform into vapor at low temperatures, encompass essential components for life, including the six most common elements found in living organisms and water. The distinctive composition of zinc in meteorites serves as a key identifier for the sources of these vital volatiles on Earth.
A team of researchers from the University of Cambridge and Imperial College London has shed light on the complex origins of Earth’s zinc, revealing that approximately half of it originated from regions beyond Jupiter, while the other half stemmed from closer to Earth within our Solar System. This groundbreaking discovery underscores the critical role of “unmelted” asteroids in providing the necessary compounds for life to thrive on our planet.
“One of the most fundamental questions on the origin of life is where the materials we need for life to evolve came from,” said Dr Rayssa Martins from Cambridge’s Department of Earth Sciences. “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.”
Planetesimals are the fundamental building blocks of rocky planets, including Earth. These diminutive entities are born through a captivating process known as accretion, where particles orbiting a young star gradually coalesce to form larger bodies.
However, not all planetesimals are created equal. The earliest planetesimals that took shape in the Solar System were subjected to intense levels of radioactivity, leading to their melting and loss of volatiles. Conversely, planetesimals that formed after the decline of these radioactive sources managed to evade the melting process, retaining a greater portion of their volatiles.
In a fascinating study, Martins and her colleagues delved into the intriguing origins of zinc on Earth. Through meticulous analysis of a diverse array of meteorites from different planetesimals, the researchers uncovered a striking revelation about our planet’s formation.
Their findings paint a compelling picture: while “melted” planetesimals contributed significantly to Earth’s mass, they surprisingly only provided a fraction of its zinc. The study’s model suggests that the majority of Earth’s zinc actually originated from unmelted or “primitive” materials, challenging previous assumptions and highlighting the crucial role of these volatile-rich sources in our planet’s history.
“We know that the distance between a planet and its star is a determining factor in establishing the necessary conditions for that planet to sustain liquid water on its surface,” said Martins, the study’s lead author. “But our results show that there’s no guarantee that planets incorporate the right materials to have enough water and other volatiles in the first place – regardless of their physical state.”
Unlocking the ability to trace elements through millions or even billions of years of evolution could prove to be an indispensable tool in the quest to discover life beyond our planet—whether on Mars or on distant planets outside our Solar System.
“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.”
Journal reference:
- Rayssa Martins, Elin M. Morton, Sven Kuthning, Saskia Goes, Helen M. Williams, Mark Rehkämper. Primitive asteroids as a major source of terrestrial volatiles. Science Advances, 2024; DOI: 10.1126/sciadv.ado4121