The moon is a barren and desolate place. The face which every human on Earth has stared at for centuries was shaped long ago by the innumerable impacts that peppered its surface. This is in stark contrast to say the surface of planets (or even some other moons) whose surfaces have been shaped through volcanic or tectonic means. This lack of surface activity is what led us to believe that the Moon was dead, a solid ball of rock that solidified many billions of years ago. However recent studies have shown that the Moon might not be as dead as we first thought with its center being not unlike that of our own Earth.
Data from the Selenological and Engineering Explorer (SELENE or Kaguya as it’s known to JAXA), as well as information gleaned from other missions, was used to model the Moon’s interior at different levels. We’ve known the rough structure of the Moon’s interior for some time now, ever since the astronauts on the Apollo missions deployed seismometers, however we never had much insight into the viscosity of those layers or whether or not the core was molten. This research shows that the mantle actually has 2 sections, the upper layer with a high viscosity and a lower layer that’s low viscosity. This would then suggest that there’s a source of heat in the Moon’s core that’s causing the lower mantle to become more liquid, indicating that the Moon’s core is likely molten.
Since the Moon is much smaller than Earth the processes that keep our core molten aren’t likely to have as much of an effect which is why it was long thought to be dead. However it appears that tidal forces, the same things that responsible for warping and shaping the moons around other planets, is what is responsible for causing the heating in the Moon’s core. In all honesty I didn’t think Earth would have the mass required to exert a strong enough tidal force to do that, we’re not exactly sitting on a gas giant, however it appears that Earth has sufficient mass to accomplish this.
Whilst this won’t be fueling the next revolution in space exploration it does open up some interesting possibilities for future expeditions to our celestial sister. Having some kind of temperature gradient opens up the possibilities of using that heat for useful work on the Moon’s surface from things like power generation to good old fashioned heating. Of course the challenge of drilling a couple kilometers into the lunar surface in order to do this is an exercise I’ll have to leave up to the reader but it’s at least an option instead of a science fiction fantasy now.
