“…Understanding the mantle evolution of the Moon that is behind its observed history of volcanic activity and radius change has been a long‐standing issue in studies of the interiors of terrestrial planets (e.g., Breuer & Moore, 2015; Kirk & Stevenson, 1989; Shearer et al., 2006; Solomon & Chaiken, 1976). The Moon expanded globally by 0.5–5 km in its earlier history until around 3.8 Gyr ago as revealed by the gravity gradiometry data (Andrews‐Hanna et al., 2013, 2014; Liang & Andrews‐Hanna, 2022; Sawada et al., 2016), and it then globally contracted until today, as suggested from observations of tectonic features on the Moon (Frueh et al., 2023; Yue et al., 2017); some observations of fault scarps (thrust faults) suggest that the contraction for the past 100 Myr is around 1 km or less (e.g., Clark et al., 2017; Klimczak, 2015; Matsuyama et al., 2021; van der Bogert et al., 2018; Watters et al., 2010, 2015). The period when its radius reached the maximum coincides with that when the mare volcanism was active: mare volcanism became more active with time for the first several hundred million years of the lunar history, peaked at 3.5–3.8 Gyr ago, and then declined but continued until around 1.5 Gyr ago (e.g., Hiesinger et al., 2000, 2003; Morota et al., 2011; Whitten & Head, 2015).…”