Technology

The story of Earth’s water has long been a subject of scientific debate. Was it delivered by comets and asteroids impacting the early planet, or was it present from the beginning? Recent research suggests the latter may be true, with a significant portion of our planet’s water potentially originating from Earth’s formation, locked away within its deep mantle. This discovery challenges existing theories and offers new insights into the conditions that made Earth habitable.

Whereas Earth doesn’t appear particularly rich in hydrogen at the surface – most exists bound to oxygen in the form of water – a team from Peking University proposes that this is merely a fraction of the total. Their research indicates the largest reservoir of hydrogen may reside within the planet’s dense, iron-rich core. Understanding the origin and distribution of hydrogen is crucial to unraveling the mysteries of planet formation and the history of water on Earth.

According to the study, published and widely reported by Live Science, the core could contain 0.07-0.36% of its mass as hydrogen, representing nine to 45 times the amount of hydrogen found in all of Earth’s oceans. This equates to potentially several sextillion kilograms of hydrogen, making the Earth’s core a surprisingly significant hydrogen reservoir. The findings, also covered by CNN, suggest that Earth’s water may have been present during its early stages of development, rather than being solely delivered by later impacts.

Investigating the core directly is currently impossible, so researchers employed laboratory models to simulate the extreme conditions found deep within the Earth. They used a diamond anvil cell to subject a small iron sphere encased in hydrated silicate glass to pressures of 111 gigapascals and temperatures of approximately 5100 Kelvin. While not a perfect replication of the core’s environment, these conditions are close enough to provide a realistic picture of how elements behave under such intense pressure and heat. The sample was completely melted, allowing the iron, silicon, oxygen, and hydrogen to freely mix, mirroring the conditions of Earth’s early, molten interior.

Hydrogen’s Affinity for Iron

The experiments revealed that hydrogen readily dissolves in iron and forms bonds with oxygen and silicon. This suggests that hydrogen could have naturally become incorporated into the forming core during Earth’s early history. This also helps explain why the core isn’t entirely composed of pure iron and why its density is lower than previously expected. The research team’s findings indicate a plausible mechanism for retaining significant amounts of hydrogen within the Earth’s interior over billions of years.

A more precise understanding of the amount of hydrogen stored in the core could deepen our understanding of Earth’s water cycle and potentially reveal whether oxygen and hydrogen can flow in and out of the planet’s interior over geological timescales. If this process occurs on other rocky planets, it raises the possibility that they too may harbor substantial water reserves beneath their surfaces, even if they appear dry from the outside. This discovery has implications for the search for habitable worlds beyond our solar system.

Implications for Planetary Science

The findings have sparked interest among planetary scientists, including Yifei Jiao from the University of California, Santa Cruz, who described the potential impact as a “rare ‘natural experiment’” offering valuable research material, according to nlc.hu. The research team is now working to refine their models and explore the implications of their findings for other planets and moons in our solar system.

What comes next involves further refining these models and exploring the implications for other planetary bodies. Continued research into the Earth’s core, even through indirect methods, will be crucial to validating these findings and unlocking the secrets of our planet’s origins. The possibility of substantial water reserves hidden within other rocky planets also fuels the ongoing search for extraterrestrial life and habitable environments.

What are your thoughts on this new theory? Share your comments below!