Near-Earth Asteroid and Meteorite Source Regions: The Big Picture

International audience"Where do meteorites come from?" has been an enduring question in planetary science, placing "traceability" (e.g. sample return) at the forefront of current exploration. Towards this goal, orbits for 2 dozen recovered meteorite falls have been determined by dedicated teams over many decades. Herewith we now add the orbits for more than 1000 near-Earth asteroids (NEAs) for which we have telescopic spectral measurements [1] sufficient to make meteorite analog assessments. For hundreds of these NEAs, their meteorite analogs have a high degree of confidence to specific classes (e.g. H, L, LL chondrites) based on detailed mineralogical modeling [2] tested against the ground truth from the Hayabusa mission [3]. As independent variables, we correlate each NEA's meteorite analog with its dynamical source region derived from the models by Granvik et al. [4,5] accounting for Yarkovsky drift and resonance delivery efficiencies. When ratioed to the overall flux rate for the diffusion of main-belt asteroids into the inner solar system, distinct source region signatures emerge for all major meteorite classes. Most interestingly, a high degree of correlation is found with respect to the compositional gradient in the asteroid belt [6,7], with the most primitive classes preferring an outer belt or Jupiter Family Comet origin. We integrate all of these results together into a new "Big Picture" view of where the major classes of meteorites come from. Observational data used in this research were obtained using the NASA Infrared Telescope Facility, which is operated by the University of Hawaii under contract NNH14CK55B with the National Aeronautics and Space Administration. This work supported by the National Science Foundation Grant 0907766 and NASA Grant NNX10AG27G. References: [1] Binzel et al. (2018), Submitted to Icarus. [2] Shkuratov et al. (1999). Icarus137, 222. [3] Nakamura et al. (2011). Science 333,1113. [4] Granvik et al. (2018). Icarus312, 181. [5] Granvik, M., Brown, P. (2018). Icarus311, 271. [6] Gradie, J., Tedesco, E.F. (1982). Science216, 1405. [7] DeMeo, F. E., Carry, B. (2014). Nature505, 629