Mercury, the closest planet to the Sun, is also one of the least known in the solar system. On the one hand, its composition is similar to that of Earth and the other rocky planets. It is made up of silicate minerals and metals, but unlike the other rocky planets, Mercury’s core makes up a much larger part, 85% (Earth’s is about 30%). As if this were not enough, it has a mysteriously persistent magnetic field that scientists still can’t explainAnd now another reason has been added: diamonds.
According to a recent study, based on simulations of the early evolution of Mercury, a team of Chinese and Belgian geoscientists found evidence that Mercury may have a layer of solid diamond beneath its crust. According to their simulations, this layer is 15 km thick, sandwiched between the core and the mantle hundreds of kilometres below the surface. Although this makes diamonds inaccessible (at least for now), these findings, published in Nature, could have implications for theories about the formation and evolution of rocky planets.
The authors, led by Bernard Charlier, were inspired by previous research by a team at MIT and NASA’s Goddard Space Flight Center. This involved a re-evaluation of Mercury’s gravitational field based on measurements taken by NASA’s MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) mission, which allowed scientists to gain a better understanding of the potential structuring of the planet’s interior. These data led the scientists to theorize that Mercury’s internal structure consisted of an outer metallic layera liquid shell and a solid inner core.
While the composition of the core remains uncertain, it seemed likely that the core contained abundant iron, nickel, silicon, and possibly sulfur and carbon. MESSENGER data led scientists to believe that the large dark spots observed on Mercury’s surface were formed largely of graphite that was probably raised from the interiorThese data suggest that sufficient amounts of carbon could have crystallized within Mercury between the core and mantle boundary and floated to the surface as graphite.
So, given the amount of graphite on Mercury’s surface, it stands to reason that the planet was saturated with carbon. Diamond was previously ruled out because it was believed that the necessary pressures did not exist near Mercury’s core to produce it. However, if the boundary between the core and the mantle was deeper than previously thought, It is possible that the necessary pressure conditions existed after all..
For their study, the team relied on thermodynamic models to recreate these pressure conditions based on the existence of a deeper boundary between the core and the mantle. These experiments allowed them to simulate what conditions were like on Mercury as it slowly cooled. Their results indicated that, assuming a sulfur content of about 11% and a pressure of about 1-2% of that inside the Earth, diamond could crystallize within the molten core.
Thus, over thousands of years, This diamond would form a layer of about 15 to 18 km thickGiven that diamond is an exceptional thermal conductor, the presence of this layer could change the way astrogeologists model Mercury’s interior dynamics and shed light on its mysterious magnetic field.
Not only is Mercury the only rocky planet other than Earth that has a magnetosphere, but it alsoThere is evidence that it could be much older than ours.. Therefore, the revised models from the interior of Mercury couldYoto explain ceitherwhy the planet’s magnetosphere has persisted for so long.