THE ORIGIN OF ASTEROID 162173 (1999 JU(3))

Near-Earth asteroid (162173) 1999 JU(3) (henceforth JU(3)) is a potentially hazardous asteroid and the target of the Japanese Aerospace Exploration Agency\u27s Hayabusa-2 sample return mission. JU(3) is also a backup target for two other sample return missions: NASA\u27s OSIRIS-REx and the European Space Agency\u27s Marco Polo-R. We use dynamical information to identify an inner-belt, low-inclination origin through the v(6) resonance, more specifically, the region with 2.15 AU \u3c a \u3c 2.5 AU and i \u3c 8 degrees. The geometric albedo of JU(3) is 0.07 +/- 0.01, and this inner-belt region contains four well-defined low-albedo asteroid families (Clarissa, Erigone, Polana, and Sulamitis), plus a recently identified background population of low-albedo asteroids outside these families. Only two of these five groups, the background and the Polana family, deliver JU(3)-sized asteroids to the v(6) resonance, and the background delivers significantly more JU(3)-sized asteroids. The available spectral evidence is also diagnostic; the visible and near-infrared spectra of JU(3) indicate it is a C-type asteroid, which is compatible with members of the background, but not with the Polana family because it contains primarily B-type asteroids. Hence, this background population of low-albedo asteroids is the most likely source of JU(3)