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PI : Suporn Boonsue

Title : Investigation and Characterization of Itokawa Regolith:Particle Interaction Processes

Abstract

Initial mineralogical and petrological analysis of Itokawa samples indicates that the majority of surface particles suffered long-term thermal annealing at approximately 800℃ and followed by shock (Nakamura et al., 2011, Science). However, the processes responsible for regolith reconsolidation and shock-induced features have not yet been completely established. We propose to characterize Itokawa regolith and regolith breccia components with an emphasis on deformation and melting phenomena, especially as these relate to how grains are bonded. We will investigate formation and modification processes of the regolith and matrix of the regolith breccia. A detailed investigation of the adhesive components of the Itokawa samples will help to address mechanisms of lithification and subsequent evolution of the asteroid components. Mineralogical and geochemical comparisons between less modified crystalline rock and mineral fragments and reprocessed regolith breccia will be performed in order to better understand the source rock of the regolith. We will use a field emission scanning electronmicroscope (Hitachi SU-70 FESEM) equipped with an Oxford Intruments high-performance X-ray detector (EDX) and Electron Backscattered Diffraction spectroscope (EBSD), as well as non-destructive micro-Raman spectroscopy (using 514.5 nm and 785 nm lasers) to determine (a) regolith surface features, (b) grain morphology, boundary features and orientation maps, (c) crystal structure, (d) mineral compositions, and (e) phase transformations (including amorphization) in select Itokawa samples. Our goal is to better understand particle interaction processes, i.e., adhesion, collision, and frictional forces between the regolith components and how these interact to generate reconsolidated materials.

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