The Moon's fragile exosphere, a sparse envelope of gas surrounding the lunar body, is mainly generated by interactions between the Moon's surface and external forces. Until now, scientists believed the solar wind played a major role in this process. But new research led by Vienna University of Technology (TU Wien) challenges that assumption.
Using original lunar rock from NASA's Apollo 16 by Robert Schreiber
Berlin, Germany (SPX) Jul 25, 2025
The Moon's fragile exosphere, a sparse envelope of gas surrounding the lunar body, is mainly generated by interactions between the Moon's surface and external forces. Until now, scientists believed the solar wind played a major role in this process. But new research led by Vienna University of Technology (TU Wien) challenges that assumption.
Using original lunar rock from NASA's Apollo 16 mission, TU Wien scientists conducted precision experiments to measure how solar wind particles actually erode the Moon's surface. The findings reveal that previous models significantly overestimated this sputtering effect due to neglecting the complex structure of lunar regolith.
"Our study provides the first realistic, experimentally validated sputtering yields for actual lunar rock," said Prof. Friedrich Aumayr from TU Wien's Institute of Applied Physics. He noted that the real erosion rate is up to ten times lower than previously predicted, primarily because the regolith is highly porous. Instead of releasing atoms upon impact, incoming ions often lose energy through multiple internal collisions, greatly reducing sputtering efficiency.
Lead author Johannes Brotzner emphasized the importance of combining laboratory data with advanced simulations: "Using a specially developed quartz crystal microbalance, we were able to measure mass loss due to ion bombardment with high accuracy. Parallel 3D simulations factored in the Moon's surface texture and porosity."
These results support conclusions drawn from a recent isotope analysis study in Science Advances, which suggested micrometeorite impacts-not solar wind-are the primary contributor to the Moon's exosphere over long timescales. TU Wien's findings independently confirm this through a different experimental lens.
The research has far-reaching implications for planetary missions. As NASA's Artemis program prepares to return humans to the Moon, and ESA and JAXA's BepiColombo mission gears up for Mercury observations, understanding how surface erosion works on airless bodies becomes increasingly critical.
Research Report:Solar wind erosion of lunar regolith is suppressed by surface morphology and regolith properties
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