Asteroidal Space Weathering: The Major Role of FeS

. Space weathering (SW) effects on the lunar surface are reasonably well-understood from sample analyses [1-3], remote-sensing data, and exper-iments [e.g. 2, 4, 5], yet our knowledge of asteroidal SW effects are far less constrained. While the same SW processes are operating on asteroids and the Moon, namely solar wind irradiation, impact vaporiza-tion and condensation, and impact melting, their rela-tive rates and efficiencies are poorly known, as are their effects on such vastly different parent materials. Asteroidal SW models based on remote-sensing data and experiments are in wide disagreement over the dominant mechanisms involved and their kinetics [e.g. 6, 7]. Lunar space weathering effects observed in UV-VIS-NIR spectra result from surface- and volume-correlated nanophase Fe metal (npFe