Late Accretion onto Terrestrial Planets

Earth and earth-like (terrestrial) planets in the inner solar system have been formed by collisions of proto-planets. Presumably, the last of such giant collision events happened, when Earth with struck by mars-sized body, ao-called Theia. It is thought that upon impact lithic fragments, molten and partly vaporized matter were ejected into the Earth, orbit where they accumulated (accreted) to form the Moon. How Earth has evolved from a glowing hot planet that was most likely covered by a couple of thousands of kilometre thick magma oceans with a metal core to a habitable planet with liquid water at the surface and an atmosphere and biosphere is the overarching goal of the research network. In this context the project focuses on the time period immediately after the formation of the Moon 4.5 Ga ago until the last mare basins on the Moon were formed by large impact events about 3.8 Ga ago. Physical, chemical and mineralogical processes (cooling, crystallisation, and segregation of elements) in the interior of Earth, but mostly the intense bombardment by cosmic bodies delivering additional mass and heat to the interior have significantly shaped this important period in the evolution of our planet, the so-called “late accretion phase”. Since almost no relicts in terms of rocks and mineral phases have been preserved on Earth the Moon is key as it can be considered as an archive of the bombardment history of the Earth-Moon-System. In this regard the Moon serves “as a window into the past of Earth”.

Together with various partners, the MfN is contributing its expertise in the field of impact and shock wave physics and meteorite research to the research project. Primarily with the aid of numerical models developed at the MfN (iSALE), it is possible to investigate the formation of large impact basins on the Moon, mixing and transport processes caused by the ongoing bombardment by asteroids, the formation of the Moon, and the creation of a global or partial magma ocean through impact processes and the incorporation of material from the impactor (in particular the metallic core) into the Earth’s interior.
 

Partners

Freie Universität Berlin (FUB)
Technical University of Berlin (TUB)
University of Münster (WWU)