Year: 2026
Type: article
Abstract: Charged‐particle sputtering is a fundamental process that contributes to the generation of the Moon’s neutral exosphere. Neutral sputtering rates are dependent on the speed, flux, and composition of the incident charged‐particle populations, all of which are variable at the Moon’s orbit. Dramatic increases in the neutral sputtering rate are likely driven by the impact of interplanetary coronal mass ejections (ICMEs). ICMEs have enhanced densities and speeds, as well as changes in their underlying composition with respect to typical solar wind values. Here, we study the role that ion composition has on the overall contributions to neutral sputtering at the Moon by analyzing in situ observations by NASA’s Advanced Composition Explorer (ACE) mission. A pre‐existing catalog of ICMEs at 1 au is used to extract relevant time periods and convolve compositionally resolved ion fluxes with laboratory sputtering yields. Median sputtered fluxes increase by factors of 2.4× and 1.5× the average solar wind value during ICME sheath and ejecta periods, respectively. Protons typically dominate sputtered fluxes from the Moon for all data, including during ICME sheath and ejecta periods; however, the contributions from alphas increases during ICME ejecta due to enhanced alpha‐to‐proton ratios. Heavy ions, including C, O, Ne, Mg, Si, and Fe typically contribute less than 10% of the total sputtered flux. Furthermore, the relative contribution of heavy ions decreases during ICME ejecta driven by strong increases in the sputtered contribution from alphas. Overall, solar wind heavy ions play an important, although not dominant, role in sputtering of the Moon’s surface.
DOI: 10.1029/2026je009972
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,070
OpenAlex ID: W7221714371