Small Bodies in the Kuiper Belt : Lessons from Pluto's Small Satellites

During the approach and flyby of the Pluto system in 2015, the instruments on theNew Horizons spacecraft obtained data on Pluto's small satellites that far surpassedwhat was previously available. All four small moons (Styx, Nix, Kerberos, and Hydra,in order of distance from Pluto) have highly irregular shapes, rapid non-synchronous rotation rates, high obliquity rotational poles, high visible albedos ( 50-80%), andneutral-to-blue visible colors. The even more detailed information obtained for Nix and Hydra reveal those 40 km diameter objects to have relatively ancient ( 3-4 Gyr) surfacesdominated by crystalline water ice, but with a hint of ammonia-containing compounds. Here we addresswhat these results say about the origin and evolution of these bodies, and howthese results inform studies of other small bodies in the Kuiper belt, including2014 MU69, the next flyby target for the New Horizons mission.