The solar system’s smallest planet may have vast riches beneath its surface, according to a stunning discovery by a NASA spacecraft.
Scientists have determined that Mercury, the closest planet to the sun, may contain a 10-mile thick mantle layer of diamonds based on data from NASA’s MESSENGER space probe, Space.com reported.
Mercury’s surface, particularly dark-colored patches of graphite, a type of carbon, have left scientists scratching their heads for decades.
The patches suggest the inner planet may once have had a carbon-rich magma ocean that would have formed the patches when the magma seeped to the surface.
The same geological process would likely have also created a carbon-rich mantle — however new data and a reevaluation of mass on the planet’s surface suggest that the mantle is not made of graphite, but precious diamond.
“We calculate that, given the new estimate of the pressure at the mantle-core boundary, and knowing that Mercury is a carbon-rich planet, the carbon-bearing mineral that would form at the interface between mantle and core is diamond and not graphite,” team member Olivier Namur, an associate professor at KU Leuven, told Space.com.
“We directly thought that this must have a huge implication for the speciation [the distribution of an element or an allotrope amongst chemical species in a system] of carbon, diamond vs graphite, on Mercury,” Namur added.
MESSENGER, which stands for “Mercury Surface, Space Environment, Geochemistry, and Ranging,” was launched in 2004 and is the first spacecraft to orbit Mercury, which it did from 2011 to 2015, mapping the entire planet and collecting data about its geology and magnetic field, according to Space.com.
The team, which published their findings in the journal Nature Communications, used a large-volume press to replicate conditions below Mercury’s crust, with temperatures reaching up to 3,950 degrees Fahrenheit.
The tests allowed the scientists to see how minerals found on the planet would have reacted in the planet’s early history.
“We believe that diamond could have been formed by two processes. First is the crystallization of the magma ocean, but this process likely contributed to forming only a very thin diamond layer at the core/mantle interface,” Namur told the outlet. “Secondly, and most importantly, the crystallization of the metal core of Mercury.”
Mercury’s core was completely liquid when the planet formed some 4.5 billion years ago, and slowly crystallized over time.
“The liquid core before crystallization contained some carbon; crystallization, therefore, leads to carbon enrichment in the residual melt,” Namur said. “At some point, a solubility threshold is reached, meaning the liquid cannot dissolve more carbon, and diamond forms.”
The diamond, which is not as dense as metal, would have floated to the top of Mercury’s core before resting between the core and mantle creating a 0.62 mile diamond layer that continued to grow over time, according to Namur.
Namur said that the shocking discovery highlights the different processes by which the other inner planets with solid surfaces, Venus, Earth and Mars, formed.
“Mercury formed much closer to the sun, likely from a carbon-rich cloud of dust. As a consequence, Mercury contains less oxygen and more carbon than other planets, which led to the formation of a diamond layer,” Namur said.
“However, Earth’s core also contains carbon, and diamond formation in the Earth’s core has already been suggested by various researchers,” he added.
