Mercury formAtion by Giant iMpact during Accretion: mass transfer, metal-silicate re-equilibration, and magma oceans

Objective

"High-energy collisions shaped planetary growth, internal structures, and surfaces. Evidence includes the cratered Moon, Mars, and Mercury; the likely impact origin of Earth’s and Mars’ moons; and metal meteorites from destroyed differentiated bodies. Mercury’s unusually large core may also reflect mantle stripping during a giant impact. Interest in Mercury has strongly increased in recent years, notably with the ESA-JAXA BepiColombo mission. Yet the giant impact hypothesis has never been tested in terms of thermochemical evolution. In this context, the applicant has designed ""MAGMA"", a project to reassess how such an event shaped Mercury and test its viability. The project will explore thermodynamic and chemical outcomes of candidate impacts, focusing on melt production and volatile partitioning between core and mantle materials from both impactor and target—key to Mercury’s thermal and chemical evolution and to interpreting BepiColombo data. Given Mercury’s particularly large core, even small differences in volatile content strongly affect its mass and measured gravity field. The work combines shock-physics simulations with laboratory experiments on element behavior under post-impact conditions, compared to spacecraft data. It merges the applicant’s expertise with an innovative experimental campaign, new to the applicant, requiring host infrastructure and supervisor expertise. Ultimately, MAGMA will assess the uniqueness of Mercury in light of the growing discovery of super-Mercury exoplanets. Beyond Mercury, the project will advance understanding of how giant impacts shape the diversity of rocky planets, including Earth. Its interdisciplinary approach will provide new tools to link geochemical signatures to dynamical histories. Results will directly benefit interpretation of ongoing missions and exoplanet observations, offering a framework to understand how extreme collisional events shape planetary systems."