Collisional fragments of Jupiter Trojans as windows into the formation of the solar system

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This project carried out at the California Institute of Technology seeks to address the origin of Jupiter Trojans, which are clusters of asteroids in Jupiter’s orbit. These two clusters sit at gravitationally stable points in the orbit, one ahead of the planet, and the other behind. The origin of these asteroids is still unknown. This project is to examine the composition of the Jupiter Trojans that have recently undergone collisions to obtain insight into their history. The exposed material will be examined using data from several ground-based observatories including the Keck Observatory and the Atacama Large Millimeter/submillimeter Array (ALMA). The broader impacts of this project include significant upgrades to a free online class available on Coursera called The Science of the Solar System. The upgrades are to include the last 5 years of space exploration and to develop new rich content based on the research into the early dynamical history of the solar system. The composition of the Jupiter Trojans provides a critical observational clue into the dynamical history of the solar system, but little is known about the compositions of these objects, because long term irradiation and continuous particle bombardment have turned their surfaces into dark refractory deposits with no identifiable spectral features. This multi-faceted project will study recent collisional fragments of Jupiter Trojan asteroids. Observing recent fragments with freshly exposed interior materials will provide insight into their composition, into their formation history, and the nature of the dynamical evolution of the early solar system. A systematic study will be carried out of objects in size from approximately 5 km, where all objects should be continuously collisionally active, up to approximately 40 km, where only the occasional object should have experienced a recent collision. Using combinations of Palomar visible photometry, Keck infrared spectroscopy, and ALMA radiometry, the albedo, composition, and collisional history of these fragments will be examined. This study will reveal the origin of these objects, their connection to the main belt of asteroids or to the Kuiper belt, and, by extension, the dynamical history of the early solar system.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.