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作者：R. S. Park, A. Berne, A. S. Konopliv, J. T. Keane, I. Matsuyama, F. Nimmo, et al.
▲ 链接：
https://www.nature.com/articles/s41586-025-08949-5
▲ 摘要：
月球因绕地球的偏心和倾斜轨道而经历了周期性的潮汐强迫。这种潮汐相互作用的响应驱动了月球重力场的时间变化，并且对卫星的内部结构很敏感。
研究组使用美国航空航天局GRAIL航天器的数据来恢复随时间变化的月球重力场，包括3级引力潮汐勒夫数k3。他们报告了k3 = 0.0163±0.0007的估计值，这比球对称卫星的估计值高出约72%。
当地幔的弹性剪切模量在近端和远端之间的变化约为2~3%时，才能解释如此大的k3，该观测证明了月球深部内部的横向非均质性。这种不对称结构表明，在近侧地幔中保存了大约100~200 K的主要热异常，该异常在30~40亿年前形成了地表月海区域，并可能影响深月震的空间分布。
▲ Abstract：
The Moon undergoes periodic tidal forcing due to its eccentric and oblique orbit around the Earth. The response to this tidal interaction drives temporal changes in the lunar gravity field and is sensitive to the satellite’s internal structure. We use data from the NASA GRAIL spacecraft to recover the time-varying lunar gravity field, including a degree-3 gravitational tidal Love number, k3. Here, we report our estimated value of k3 = 0.0163 ± 0.0007, which is about 72% higher than that expected for a spherically symmetric moon. Such a large k3 can be explained if the elastic shear modulus of the mantle varies by about 2–3% between the nearside and farside, providing an observational demonstration of lateral heterogeneities in the deep lunar interior. This asymmetric structure suggests preservation of a predominantly thermal anomaly of roughly 100–200 K in the nearside mantle that formed surface mare regions 3–4 billion years ago and could influence the spatial distribution of deep moonquakes.
