A group of scientists from the Lunar and Planetary Laboratory at the University of Arizona has, for the first time, meticulously reconstructed the early history of the Moon.
The study, published in the journal Nature Geoscience, sheds light on the origin of basaltic lunar rocks with high titanium content, samples of which were brought to Earth by astronauts almost 60 years ago.
There is a theory that the Moon formed as a result of a collision between a young Earth and the dwarf planet Theia. Debris ejected into orbit gradually coalesced, forming the satellite. It is likely that in the early stages, the Moon was covered in magma, forming the mantle and crust, with remnants of lava crystallizing into titanium and iron minerals such as ilmenites below the surface.
Over millennia, the mineral layer on the Moon subsided, mixing with the mantle, and then resurfaced as titanium-rich lava flows. Theoretical models suggest that this layer initially migrated to the nearside of the Moon due to the impact of a large body, and then subsided inward as a network of sheet-like plates.
Scientists compared these models with data obtained from the GRAIL A and GRAIL B spacecraft, which orbited the Moon in 2011-2012 and measured its gravitational field.
Gravity maps confirmed the presence of a subsurface ilmenite layer, which remained after the submersion of other minerals. Such anomalies are interrupted by large basins on the surface, indicating their earlier formation.
The study’s authors speculated that the ilmenite layer submerged over 4.3 billion years ago.
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