Forming the Moon from terrestrial silicate-rich material

TL;DR

This paper explores an alternative lunar formation hypothesis where the Moon forms from terrestrial mantle material ejected by a nuclear explosion at Earth's core-mantle boundary, addressing geochemical inconsistencies in the giant impact model.

Contribution

It proposes a novel lunar formation mechanism involving nuclear explosion-induced ejection of mantle material, supported by hydrodynamic modeling.

Findings

Nuclear fission can provide the energy needed for lunar material ejection.

Hydrodynamic simulations show shock waves can disrupt and expel mantle material.

The scenario offers an alternative to the giant impact model considering isotopic similarities.

Abstract

Recent high-precision measurements of the isotopic composition of lunar rocks demonstrate that the bulk silicate Earth and the Moon show an unexpectedly high degree of similarity. This is inconsistent with one of the primary results of classic dynamical simulations of the widely accepted giant impact model for the formation of the Moon, namely that most of the mass of the Moon originates from the impactor, not Earth. Resolution of this discrepancy without changing the main premises of the giant impact model requires total isotopic homogenisation of Earth and impactor material after the impact for a wide range of elements including O, Si, K, Ti, Nd and W. Even if this process could explain the O isotope similarity, it is unlikely to work for the much heavier, refractory elements. Given the increasing uncertainty surrounding the giant impact model in light of these geochemical data, alternative hypotheses for lunar formation should be explored. In this paper, we revisit the hypothesis that the Moon was formed directly from terrestrial mantle material. We show that the dynamics of this scenario requires a large amount of energy, almost instantaneously generated additional energy. The only known source for this additional energy is nuclear fission. We show that it is feasible to form the Moon through the ejection of terrestrial silicate material triggered by a nuclear explosion at Earths core-mantle boundary (CMB), causing a shock wave propagating through the Earth. Hydrodynamic modelling of this scenario shows that a shock wave created by rapidly expanding plasma resulting from the explosion disrupts and expels overlying mantle and crust material.