Space Weathering Effects in Troilite by Simulated Solar-Wind Hydrogen and Helium Ion Irradiation

J. M. Christoph, G. M. Minesinger, C. Bu, C. A. Dukes, L. T. Elkins-Tanton

Research output: Contribution to journalArticlepeer-review

Abstract

Space weathering is a key process in the interpretation of airless planetary surfaces. As we engage new missions to planetary objects with potentially novel surfaces such as 16 Psyche, there is renewed interest in expanding our knowledge of space weathering effects to a wider variety of analog materials, including the physical/chemical effects of solar-wind ions on planetary regoliths. We have experimentally simulated the effects of solar ions on two polished thick sections of meteoritic troilite (FeS) via irradiation with 1 keV hydrogen (H+) and 4 keV helium (He+), to investigate effects resulting from different ion species. We detected depletion of sulfur over the course of each irradiation using in situ X-ray photoelectron spectroscopy. Sulfur depletion rates were surprisingly similar for H+ and He+, interpreted as a function of subsurface ion-activated diffusion. By comparing XPS-derived elemental abundances with SDTrimSP computer simulations, we further quantified sulfur diffusion, sputtering yield, and altered-layer composition with respect to incident-ion fluence, and accounted for the influence of surface oxidation due to atmospheric sample storage. Using scanning electron microscopy, we detected an increase in nanoscale surface roughness resulting from the irradiation, which we quantified using atomic force microscopy. Based on these results, we estimate that an exposure time of order 103 Earth-years is required for troilite on Psyche to reach equilibrium sulfur depletion within the first atomic layer.

Original languageEnglish (US)
Article numbere2021JE006916
JournalJournal of Geophysical Research: Planets
Volume127
Issue number5
DOIs
StatePublished - May 2022
Externally publishedYes

Keywords

  • asteroid
  • meteorite
  • Psyche
  • solar wind ion
  • space weathering
  • surface

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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