Bombardment history of the planets

University Of Arizona, Tucson AZ

Investigators

Abstract

AST-0806828 Malhotra It is becoming increasingly clear that the planets and the planetesimals (the asteroids and Kuiper belt objects) in the solar system have co-evolved, such that the planets migrate and the planetesimal belts are depleted, while the bombardment rate on the planets evolves. This project will detail one crucial phase in this evolution, associated with the late heavy bombardment (LHB), some 3.9 billion years ago. Building on earlier evidence for the source and the mechanism of this event, this investigation will assess the number, sizes, and changing impact rates of the LHB and post-LHB impactors. Rigorous analysis and numerical modeling combined will identify the dominant and less dominant sources of the LHB and post-LHB impactors, and provide upper and lower limits on the duration of the LHB, its intensity on the Earth, Moon and other terrestrial planets, and the magnitude of depletion of the main asteroid belt. This research helps to understand the dynamical history of the planets and minor bodies of the solar system, especially the bombardment history of planet Earth, the crater-based geochronology of Mars and Mercury, and the history of the main asteroid belt. It adds impetus to renewed study of the Moon, and is also of interest to extra-solar planetary system studies. Knowledge gained during the study will be integrated into Dr Malhotra's natural sciences class, and meteorite bombardment and the history of early Earth have broad public and community interest.