Produced by: Tarun Mishra Designed by: Manoj Kumar
Using data from NASA’s MESSENGER spacecraft, scientists have identified a potential 10-mile-thick diamond mantle beneath Mercury’s crust. This finding suggests the planet may harbour more secrets than previously thought.
Mercury has long baffled scientists due to its unique traits, such as its dark surface, dense core, and early end to volcanic activity. These characteristics set it apart from other planets in the solar system.
The presence of graphite patches on Mercury’s surface led scientists to hypothesize a carbon-rich magma ocean in its early history. This ocean could have created the graphite patches and the planet’s dark surface hue.
Researchers now propose that Mercury’s mantle is not made of graphite but a more valuable carbon allotrope: diamond. The formation of this diamond layer is attributed to the high-pressure conditions at the mantle-core boundary.
The conclusions are based on geophysical data collected by the MESSENGER spacecraft, which orbited Mercury and mapped its surface from 2011 to 2015. This mission provided crucial insights into Mercury’s geology and magnetic field.
Scientists replicated Mercury’s interior conditions on Earth using a large-volume press, applying over seven gigapascals of pressure to synthetic silicate. These experiments helped study how minerals change under such extreme conditions.
The team believes the diamond layer could have formed through two processes: the crystallization of a carbon-rich magma ocean and the progressive crystallization of Mercury’s initially liquid core, which enriched the remaining melt with carbon.
This discovery might explain why Mercury’s major volcanic activity ended relatively quickly, around 3.5 billion years ago. A diamond layer could have facilitated rapid heat removal, leading to the early termination of volcanism.
The research team plans to further investigate the thermal effects of a diamond layer at the mantle-core boundary. They anticipate new data from the BepiColombo mission, expected in 2026, to enhance their understanding of Mercury’s internal structure and evolution. The study was published in Nature Communications.