Researchers have uncovered new insights into how the building blocks of life arrived on Earth, suggesting that “unmelted” asteroids played a crucial role in delivering volatile elements necessary for life to emerge. A team from the University of Cambridge and Imperial College London analyzed the chemical fingerprints of zinc contained in meteorites to determine the origin of these essential compounds.
Led by Dr. Rayssa Martins, the study found that about half of Earth’s zinc came from beyond Jupiter, while the other half originated closer to our planet. The researchers discovered that “primitive” planetesimals, which formed later in the Solar System and avoided melting, were responsible for supplying most of Earth’s volatiles, including water. This breakthrough could have significant implications for the search for life elsewhere in the universe, as it highlights the importance of considering the source of volatile elements when searching for habitable planets.
The Origin of Volatile Elements on Earth
The building blocks of life, including volatile elements such as water and the six most common elements found in living organisms, have been a subject of interest for researchers studying the origin of life on Earth. A recent study published in Science Advances has shed light on the source of these essential compounds, suggesting that they may have originated from “unmelted” asteroids.
Volatiles are elements or compounds that change into vapor at relatively low temperatures. They play a crucial role in the emergence and sustenance of life on Earth. The researchers used the chemical fingerprints of zinc contained in meteorites to determine the origin of volatile elements on Earth. Zinc, with its unique composition, can be used to identify the sources of Earth’s volatiles.
The study found that about half of Earth’s zinc came from beyond Jupiter and half originated closer to Earth. This discovery has significant implications for our understanding of how life emerged on Earth. According to 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.”
The Role of Planetesimals in Shaping Earth’s Composition
Planetesimals are the main building blocks of rocky planets like Earth. These small bodies are formed through a process called accretion, where particles around a young star start to stick together, forming progressively larger bodies. However, not all planetesimals are created equal. The earliest planetesimals that formed in the Solar System were exposed to high levels of radioactivity, which caused them to melt and lose their volatiles.
In contrast, some planetesimals formed after these sources of radioactivity were mostly extinct, helping them survive the melting process and preserve more of their volatiles. The researchers measured the zinc from a large sample of meteorites originating from different planetesimals and used this data to model how Earth got its zinc. Their results show that while “melted” planetesimals contributed about 70% of Earth’s overall mass, they only provided around 10% of its zinc.
The Importance of Unmelted Materials in Supplying Volatiles
The study’s findings suggest that unmelted, or “primitive,” materials were an essential source of volatiles for Earth. Dr. Martins states, “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. But our results show 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.”
The ability to trace elements through millions or even billions of years of evolution could be a vital tool in the search for life elsewhere, such as on Mars, or on planets outside our Solar System. The researchers’ results highlight the importance of considering the role of different materials in supplying volatiles when searching for habitable planets.
Implications for the Search for Life Elsewhere
The study’s findings have significant implications for the search for life beyond Earth. According to Dr. Martins, “Similar conditions and processes are also likely in other young planetary systems. The roles these different materials play in supplying volatiles is something we should keep in mind when looking for habitable planets elsewhere.”
The research was supported in part by Imperial College London, the European Research Council, and UK Research and Innovation (UKRI). The study’s results provide a new perspective on the origin of life on Earth and highlight the importance of considering the role of different materials in supplying volatiles when searching for habitable planets.
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