2024-04-12 11:00:15
Researchers at the University of Arizona have shed light on the mystery of the Moon’s “asymmetric” geology, combining computer simulations and space data. Their study, published in Nature Geosciencereveals a crucial chapter in history lunarshedding light on the evolution of its interior and, by extension, that of planets like Earth or Mars.
Credit: Adrien Broquet/University of Arizona & Audrey Lasbordes
The birth of the Moon, approximately 4.5 billion years ago, resulted from the collision between the Earth and a small planet. This catastrophe cosmic force projected debris into space, which clumped together to form our satellite naturel. Knowledge of this process comes largely from analysis of lunar rock samples collected by the Apollo missions more than fifty years ago and subsequent satellite observations, revealing a surprisingly high concentration of titanium on the near side of the Moon . The explanation for this distribution remained a mystery until now.
The Moon formed quickly and at high temperature, probably covered by an ocean of magma. As this magma cooled and solidified, it formed the lunar mantle and crust. However, dense minerals like ilmenite, rich in titanium and iron, formed a gravitational instability, causing them to sink toward the Moon’s interior.
The visible side of the Moon, with its dark regions or “seas”, covered in titanium-rich volcanic flows (center), constitutes the familiar appearance of the Moon from Earth (left).
The dark region is surrounded by a pattern of gravity anomalies (blue in the right image) interpreted as the remnants of dense material that sank.
Credit: Adrien Broquet/University of Arizona
This process of “mantle reversal” left behind vestiges materialized by gravitational anomalies, revealed by NASA’s GRAIL mission. These anomalies surround vast dark regions on the visible side of the Moon, the “seas”, covered with volcanic lava flows.
The recent study confirms that these gravitational signatures match predictions from models of sinking ilmenite layers, providing the first physical evidence of a global overthrow of the lunar mantle more than 4 billion years ago. This discovery helps clarify how and when this event occurred, highlighting theasymmetry fundamental of the Moon in all respects, notably the region of the Ocean of Storms (Oceanus Procellarum), lower, with a thinner crust, and rich in elements such as titanium and thorium.
These discoveries have important implications for future exploration of the Moon, particularly for the Artemis missions, which will benefit from an understanding update of our satellite.
1712986799
#lunar #surface #sank #crust