Effect of Internal Structure on the Formation of Binary Near-Earth Asteroids

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This project is a study of the effect of internal structure on the origin and evolution of binary near-Earth asteroids (NEAs). Previous NSF-supported work has shown that tidal disruption alone cannot account for the high population fraction of binary NEAs. However, the YORP thermal effect can, and also explains the critical rotation, diamond shape, and raised equatorial ridge of the best-studied binary NEA. YORP can also explain the provenance of small inner Main Belt asteroid binaries, which have not experienced tidal disruptions. Bearing in mind preliminary results on how weak cohesion affects disruption outcome, the new work includes 1) a systematic study of the effect of particle size distribution, particle shape, and simulation resolution on tidal and YORP-style rotational disruption; 2) development and deployment of a weak cohesion model; and 3) maintenance and dissemination of a database of binary asteroid properties. The team's unique high-performance simulation tools have already been responsible for important advances in the study of binary NEA formation, and this study will establish the relative importance of rubblized structure, weak cohesion, and contact binarity, on the provenance of binary asteroids. In light of rapidly improving observations and new data from recent and forthcoming spacecraft missions, this theoretical research is an important part of our understanding of the nature and evolution of small bodies in the solar system.Results from this research bear on the internal structure of NEAs, with implications both for sample return missions and for hazard mitigation strategies. The work will be the bulk of a graduate student thesis, will involve undergraduates, and will update a public repository of observed binary small bodies. This research will also strengthen international ties between the University of Maryland and l'Observatoire de la Côte d'Azur in Nice, France.