Could primitive asteroids hold the key to life on Earth? New study reveals their role in Earth's volatiles

A new study suggests that primitive asteroids played a vital role in delivering essential volatiles, such as water, to Earth, forming the basis for life.

Primitive asteroids played a key role in delivering vital volatile elements, such as water, to Earth, forming the foundation for life.

Researchers have traced Earth's volatile elements to primitive asteroids, which provided key compounds necessary for life. These asteroids, unlike their melted counterparts, preserved crucial volatiles like water and zinc. The study, led by scientists from the University of Cambridge and Imperial College London, offers insights into how life-supporting materials may have originated on Earth and their potential role in other planetary systems.

The Role of Primitive Asteroids in Earth's Volatiles

Volatiles, such as water and certain gases, are crucial for life to form and thrive on Earth. Researchers have long debated how Earth acquired these elements, but the recent study, published in Science Advances has pinpointed primitive asteroids as a major source. Led by Dr. Rayssa Martins from Cambridge’s Department of Earth Sciences, the study used the unique chemical signature of zinc found in meteorites to trace the origins of Earth's volatile elements, suggesting that unmelted asteroids were key contributors.

“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. Martins.

The researchers analyzed a large sample of meteorites originating from different planetesimals, solid objects that formed in the early solar system from dust and gas, examining how Earth gained its volatiles over millions of years of formation.

Their findings suggest that while Earth’s mass was mostly formed from melted planetesimals, the unmelted asteroids provided the essential volatile materials, including a large percentage of Earth’s zinc.

How Primitive Asteroids Escaped Melting

During the formation of the Solar System, many planetesimals—the building blocks of planets—were exposed to extreme heat and radioactivity, causing them to melt and lose many volatiles. However, Dr. Martins' study focused on planetesimals that formed later, after most radioactive sources had decayed. These asteroids, which did not undergo melting, preserved their volatiles.

The team’s research revealed that while melted planetesimals contributed about 70% of Earth’s overall mass, they supplied only around 10% of its zinc, a critical volatile element. This indicates that primitive, unmelted asteroids played a far more significant role in delivering volatiles to Earth, which were necessary for the emergence of life.

Study Results and Implications for Life on Other Planets

Dr. Martins and her team’s findings show that Earth’s volatiles likely came from a mix of melted and primitive asteroids. A large portion of zinc and other essential compounds needed for life were delivered by primitive asteroids that avoided melting.

These insights could have broader implications for finding life beyond Earth. The study suggests that other planets in young planetary systems might follow similar patterns. As researchers continue to explore planets like Mars and distant exoplanets, the role of primitive materials could be key in identifying whether they have the right ingredients for life.

News reference:

University of Cambridge. “How did the building blocks of life arrive on Earth?”

https://www.cam.ac.uk/research/news/how-did-the-building-blocks-of-life-arrive-on-earth