Compositional Diversity Among Primitive Asteroids HUMBERTO CAMPINS1, JULIA DE LEÓN2, JAVIER LICANDRO2, AMANDA HENDRIX3, JUAN A. SÁNCHEZ3 AND VICTOR ALI-LAGOA4 1University of Central Florida, Orlando, Florida, USA.
[email protected] 2 Institute of Astrophysics of the Canaries, Tenerife, Spain 3 Planetary Science Institute, Tucson, Arizona, USA 4 Max Planck Institute for Extraterrestrial Physics, Garching, Germany In Primitive Meteorites and Asteroids, Physical, Chemical, and Spectroscopic Observations Paving the Way to Exploration, Editor: Neyda Abreu, published by Elsevier July 17, 2018 ABSTRACT. Spectroscopic observations from the ultraviolet to the mid-infrared have revealed new and diagnostic differences among primitive asteroids. We review the spectral characteristics of these asteroids and their inferred compositional and physical properties. Primitive asteroids throughout the belt show carbon-rich compounds, varying degrees of aqueous alteration and even surface ice; recent observations provide significant new constraints on composition, thermal inertia, and other surface properties. New mid-infrared connections between primitive asteroids and interplanetary dust particles indicate that the latter sample a larger fraction of main belt asteroids than meteorites. Links with the composition of comets are consistent with a proposed continuum between primitive asteroids and comets. Two sample-return missions, OSIRIS-REx and Hayabusa 2, will visit primitive near-Earth asteroids (NEAs). Most spacecraft-accessible NEAs originate in the inner asteroid belt, which contains several primitive asteroid families and a background of primitive asteroids outside these families. Initial results from these families offer a tantalizing preview of the properties expected in the NEAs they produce. So far, primitive asteroids in the inner belt fall into two spectral groups.