The Cassini state equilibrium associated with the precession of the Moon predicts that the mantle, fluid core, and solid inner core precess at different angles. We present estimates of the dissipation from viscous friction associated with the differential precession at the core‐mantle boundary (CMB), Q _{c m b} , and at the inner core boundary (ICB), Q _{i c b} , as a function of the evolving lunar orbit. We focus on the latter and show that, provided the inner core was larger than 100 km, Q _{i c b} may have been as high as 10¹⁰–10¹¹ W for most of the lunar history for a broad range of core density models. This is larger than the power required to maintain the fluid core in an adiabatic state; therefore, the heat released by the differential precession at the ICB can drive a past lunar dynamo by thermal convection. This dynamo can outlive the dynamo from precession at the CMB and may have shut off only relatively recently. Estimates of the magnetic field strength at the lunar surface are of the order of a few μT, compatible with the lunar paleomagnetic intensities recorded after 3 Ga. We further show that it is possible that a transition of the Cassini state associated with the inner core may have occurred as a result of the evolution of the lunar orbit. The heat flux associated with Q _{i c b} can be of the order of a few mW m⁻², which should slow down inner core growth and be included in thermal evolution models of the lunar core.

中文翻译：

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过去的内核驱动的岁月发电机

与月球进动相关的卡西尼状态平衡表明，地幔，流体核和固体内核进动在不同的角度。我们提出了与芯壳边界（CMB）Q _{c m b}和内芯边界（ICB）Q _{i c b}的微分进动相关的粘性摩擦耗散的估计值，它是不断演化的函数月球轨道。我们关注后者，并表明，如果内芯大于100 km，则Q _{i c b}可能高达10 ¹⁰ –10 ¹¹W用于大多数月球历史，适用于各种核心密度模型。这比将流体芯保持在绝热状态所需的功率大。因此，ICB的差动进动释放的热量可以通过热对流驱动过去的发电机。该发电机可以使CMB的进动寿命更长，并且可能只是在最近才关闭。月球表面磁场强度的估计值约为几μT，与3 Ga之后记录的月球古磁场强度兼容。我们进一步表明，与内芯相关的卡西尼状态的转变可能是由于月球轨道的演变而发生的。与Q _{i c b}相关的热通量可以约为几mW m ^{-2的数量级}，这应该减慢内核的生长，并应包括在月球核心的热演化模型中。