Erosion of the lunar surface by solar wind ions

Abstract

Solar wind sputtering is a key process driving material ejection from the lunar surface and contributing to the exosphere [1 –5]. We present high-precision sputter yield measurements on Apollo 16 regolith sam- ples, complemented by advanced 3D regolith modeling. Our results show that sputter yields for H and He ions at solar wind energies are nearly an order of magnitude lower than previously assumed. This significant reduction is attributed to surface roughness and porosity effects, which have not been adequately considered in past studies. Additionally, our data reveal discrepancies with numerical predictions that have otherwise been reliable for single minerals, suggesting that the properties of lunar regolith are not just a linear combination of its constituents. By providing experimentally validated sputter yields for real lunar ma- terial, our work challenges existing exosphere models and offers a cru- cial benchmark for future studies. These findings have broad implica- tions for interpreting data from upcoming missions like Artemis and BepiColombo and for understanding space weathering on airless plan- etary bodies in general.