Researchers from the University of Cambridge and Imperial College London have uncovered new clues about how life’s essential elements arrived on Earth.
They used a special technique to study the chemical fingerprints of zinc found in meteorites.
Their findings suggest that without certain types of asteroids, Earth might not have had the necessary compounds to support life.
Volatile elements are those that easily turn into vapor at low temperatures.
These include important elements for life like carbon, nitrogen, and oxygen, as well as water.
The zinc in meteorites has a unique chemical signature, which can be used to trace where Earth’s volatiles originated.
The researchers discovered that Earth’s zinc supply came from two main parts of the Solar System: about half from areas beyond Jupiter and half from regions closer to Earth.
This split provides vital clues about the origins of life-supporting materials.
Dr. Rayssa Martins from Cambridge’s Department of Earth Sciences explained, “One of the key questions in the origin of life is where these essential materials came from.
By understanding how they arrived on Earth, we might find hints about how life began here and possibly elsewhere.”
The team focused on the role of planetesimals—small space objects that were the building blocks of planets like Earth. These bodies formed through a process called accretion, where dust and particles around a young star stick together and grow larger over time.
However, not all planetesimals are alike. The earliest ones in the Solar System were exposed to high levels of radioactivity, which caused them to melt and lose their volatile elements. But others formed later, when this radioactivity had mostly died down, allowing them to keep their volatile materials.
In their study, published in Science Advances, the researchers analyzed a large set of meteorites from different planetesimals. They measured the amount and composition of zinc in these meteorites and built a model to trace Earth’s zinc over the millions of years of its formation.
Their results revealed that while the ‘melted’ planetesimals provided around 70% of Earth’s total mass, they only supplied about 10% of its zinc. The rest of Earth’s zinc came from materials that didn’t melt, referred to as ‘primitive’ materials. These unmelted materials were crucial for delivering the volatiles needed to support life on Earth.
The study highlights that while a planet’s distance from its star can create conditions for liquid water, it’s not enough to guarantee life-supporting elements. “Our findings show that having the right materials is just as important,” said Dr. Martins.
The research also suggests that similar processes could happen in other young planetary systems. Tracing these elements over millions or billions of years may be a key tool in searching for life on planets like Mars or those beyond our Solar System.
This study was supported by Imperial College London, the European Research Council, and UK Research and Innovation (UKRI).
Source: University of Cambridge.
