@article{f26cabee94a34519a81522fe7a113c21,
title = "Space Weathering Effects in Troilite by Simulated Solar-Wind Hydrogen and Helium Ion Irradiation",
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.",
keywords = "Psyche, asteroid, meteorite, solar wind ion, space weathering, surface",
author = "Christoph, {J. M.} and Minesinger, {G. M.} and C. Bu and Dukes, {C. A.} and Elkins-Tanton, {L. T.}",
note = "Funding Information: This work is supported by NASA contract NNM16AA09, “Psyche: Journey to a Metal World.” The authors acknowledge the use of facilities within the Eyring Materials Center at Arizona State University supported in part by NNCI-ECCS-1542160. J.M.C thanks the staff and researchers at the CMS and the Eyring Materials Center at Arizona State University. C.A.D. acknowledges support from the NASA SSW Working Program (NNX15AM38G) and NSF Astronomy (2009365). The NSF MRI Program (1626201) is acknowledged for UVa's PHI Versaprobe III XPS. G.M.M. was supported by the Virginia Initiative for Cosmic Origins (VICO) and the Psyche Mission. The authors are grateful to M. Thompson, L. Chaves, and one anonymous reviewer for their recommendations, which improved this paper significantly. Thanks also to D. Rogers, S. Dibb, A. Gerhard, and others for editorial assistance. Funding Information: This work is supported by NASA contract NNM16AA09, “Psyche: Journey to a Metal World.” The authors acknowledge the use of facilities within the Eyring Materials Center at Arizona State University supported in part by NNCI‐ECCS‐1542160. J.M.C thanks the staff and researchers at the CMS and the Eyring Materials Center at Arizona State University. C.A.D. acknowledges support from the NASA SSW Working Program (NNX15AM38G) and NSF Astronomy (2009365). The NSF MRI Program (1626201) is acknowledged for UVa's PHI Versaprobe III XPS. G.M.M. was supported by the Virginia Initiative for Cosmic Origins (VICO) and the Psyche Mission. The authors are grateful to M. Thompson, L. Chaves, and one anonymous reviewer for their recommendations, which improved this paper significantly. Thanks also to D. Rogers, S. Dibb, A. Gerhard, and others for editorial assistance. Publisher Copyright: {\textcopyright} 2022 The Authors.",
year = "2022",
month = may,
doi = "10.1029/2021JE006916",
language = "English (US)",
volume = "127",
journal = "Journal of Geophysical Research: Planets",
issn = "2169-9097",
publisher = "Wiley-Blackwell Publishing Ltd",
number = "5",
}