The Visible Spectral Properties of Trojans and NEOs

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The Trojan asteroids orbit the Sun in a 1:1 resonance with Jupiter, centered on, and librating around, that planet's L4 and L5 Lagrange points. Originally thought to have been captured form the outer parts of the asteroid belt, the Trojans are proposed in newer theories to have been captured from the Kuiper belt during a period of extreme mixing of the small bodies of the Solar System. In-depth study of these objects provides constraints on the degree of dynamical mixing in the early Solar System as well as on the compositions of primitive bodies. In this project, the Principal Investigator and collaborators will use ground-based telescopes in Arizona and South Africa to make visible and near-infrared spectrophotometric observations of hundreds of Trojan asteroids as well as dozens of near-Earth objects (NEOs), obtaining taxonomic classifications and spectral slopes. Determining the relative fractions of the dominant taxonomic classes at different sizes of Trojans will constrain dynamical mixing implied by the "Nice Model" of the early Solar System. By combining new and archival data, the team hopes also to determine whether the different spectral types seen are related by "space weathering" processes or actually reflect compositional differences. The NEO observations will complement other ongoing observational programs and are designed to aid in the timely characterization of potentially hazardous objects and possible space mission targets.