Global Study of Small-scale Color Features on 433 Eros, the Effect of Residual Scattered Light and Implications for Ponded Deposit Formation Mechanisms

Introduction: Utilizing all viable MSI color image sequences, we cataloged every resolvable spectral/albedo unit on Eros: high reflectance streaks, dark soils, ponded deposits and average regolith. This complete catalog increases our understanding of regolith processes on Eros and provides additional constraints on understanding the significance of compositional and maturity variations on airless silicate bodies. A new detailed analysis of residual scattered light is presented and used to constrain interpretations of the spectral ratios. The nature of the residual scattered light indicates that we are unable to obtain a pure uncontaminated spectrum of ponded material. Background: The NEAR Shoemaker spacecraft orbited 433 Eros, a Near Earth Asteroid in 20002001. Earth-based telescopic spectra indicated, and the NEAR Infrared Spectrometer (NIS) confirmed, that Eros is composed of mafic silicates, olivine (Mg,Fe)2SiO4 and pyroxene (Mg,Fe,Ca)2Si2O6 [1,2]. Four types of albedo/spectral features have been identified in previous studies (Figure 1). High reflectance streaks are high albedo streaks found on steep slopes. Dark soils are low albedo deposits found in topographic lows and frequently associated with white streaks. Ponded deposits are flat, smooth deposits that infill topographic lows normal to local gravity. Average Eros is typical regolith.