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Coordinated Nanoscale Compositional and Oxidation State Measurements of Lunar Space‐Weathered Material
Author(s) -
Burgess K. D.,
Stroud R. M.
Publication year - 2018
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
eISSN - 2169-9100
pISSN - 2169-9097
DOI - 10.1029/2018je005537
Subject(s) - space weathering , regolith , weathering , astrobiology , materials science , microscale chemistry , nanoscopic scale , mineralogy , dissolution , geology , chemical engineering , nanotechnology , geochemistry , physics , asteroid , mathematics education , mathematics , engineering
Abstract Space weathering on airless bodies includes a number of processes, such as micrometeorite impacts and solar wind bombardment, which leads to a variety of microscale to nanoscale alteration features, including vapor deposited layers on grain and rock surfaces and creation of nanophase opaque inclusions. The nanophase inclusions cause reddening and darkening of the visible to near‐infrared spectra of space weathered material, features associated with increasing space exposure of many airless body regoliths. On the Moon, most nanophase inclusions are metallic iron (npFe 0 ), but recent work using aberration‐corrected scanning transmission electron microscopy and electron energy loss spectroscopy has provided evidence of oxidized nanoparticles in space weathered lunar soil grains. We examined three different lunar soils in order to confirm the finding of oxidized nanophase inclusions and to provide detailed elemental and mineralogical information about the surrounding material. Our data show that substrate and rim composition are key factors in determining whether highly localized oxidation occurs; for example, nanophase inclusions in rims on low Fe substrates are more prone to oxidation. Detailed understanding of the phases and features present in these samples is necessary for the correct interpretation of remotely sensed data as well as extrapolation from processes on the lunar surface to those on other airless bodies.