Sputter Yields of the Lunar Surface: Experimental Validation and Numerical Modelling of Solar Wind Sputtering of Apollo 16 Soils

• Main Authors: Brötzner, Johannes, Biber, Herbert, Szabo, Paul Stefan, Jäggi, Noah, Fuchs, Lea, Nenning, Andreas, Fellinger, Martina, Nagy, Gyula, Pitthan, Eduardo, Primetzhofer, Daniel, Mutzke, Andreas, Wilhelm, Richard Arthur, Wurz, Peter, Galli, André, Aumayr, Friedrich
• Format: Journal Article
• Language: English
• Published: 18-10-2024
• Subjects: Physics - Earth and Planetary Astrophysics; Physics - Instrumentation and Methods for Astrophysics; Physics - Solar and Stellar Astrophysics; Physics - Space Physics
• DOI: 10.48550/arxiv.2410.14450

Sputtering by solar wind ions is a key process driving the ejection of
high-energy particles into the exospheres of airless bodies like asteroids,
Mercury and the Moon. In view of upcoming missions which will deliver new
in-situ data on these exospheres like the Artemis program at the Moon and
BepiColombo at Mercury, a deeper understanding of sputtering effects is
crucial. In this work, we combine sensitive quartz crystal microbalance
measurements and numerical simulations to quantify sputter yields of Apollo
soil 68501 under solar wind relevant conditions. We find that none of the
commonly used simulation codes can reliably predict laboratory sputter yields
without experimental benchmarks. All of the employed packages significantly
overestimate the sputter yields of flat samples by at least a factor of 2 for
the case of hydrogen. When accounting for surface roughness and regolith-like
porosity, sputter yields are decreased even further to 7.3E-3 atoms\ion and
7.6E-2 atoms\ion for H and He at solar wind energies of 1 keV\amu,
respectively. The reduced yields of porous regolith structures are largely
independent of the ion incidence angle, making them applicable across a wide
range of lunar latitudes. This study highlights the need for experimental
validation of sputtering models to ensure accurate predictions for space
weathering and lunar exosphere composition.