月の土壌粒子中の空隙がH₂O分子を生み出す場所だった～太陽風による新たな水生成メカニズムを解明、将来の月面資源利用にも期待～

2026-02-09 東京大学

月面の土壌粒子中に存在している直径数ナノメートルから数十ナノメートルの空隙中でH₂Oが形成

＜関連情報＞

• https://www.s.u-tokyo.ac.jp/ja/press/11048/
• https://www.nature.com/articles/s41598-025-34389-2

月面土壌の小胞における太陽風誘起H2O生成と保持の分子動力学シミュレーション Molecular dynamics simulations of solar-wind induced H2O formation and retention in vesicles of lunar soil

Daigo Shoji
Scientific Reports  Published:09 February 2026
DOI:https://doi.org/10.1038/s41598-025-34389-2

Abstract

Several observations have shown that the lunar surface contains both H₂O molecules and OH. One possible origin of these chemical species are implanted solar-wind hydrogen. However, the reaction pathway from hydrogen to H₂O remains unclear. Here, we use reactive molecular dynamics simulations to investigate H₂O formation at vesicle walls in plagioclase grains. When hydrogen atoms were implanted into plagioclase containing a spherical vesicle, 2–3 times more hydrogen became preferentially trapped at the vesicle wall as OH due to oxygen dangling bonds. The accumulation of OH and subsequent trapping of hydrogen atoms led to the synthesis of H₂O molecules. If the trapped hydrogen does not diffuse over several lunar days, which is plausible given the strong bonding energy of the dangling bonds (>5 eV), up to a few wt% of H₂O can form near vesicle walls. Furthermore, in vesicles lacking pathways to the outer space, their closed structure inhibits H₂O diffusion, consistent with the detection of H₂O in Apollo soils.