As a citizen scientist, I would like to postulate the following idea:
A Sizable Moon is a Necessary Part in Producing a Planet’s Magnetosphere and Ultimately Able to Support Life.
I am not simply talking about our Moon keeping the planet’s axis tilt at an angle that makes our seasons predictable. Nor am I talking about tidal forces on our oceans. I am talking specifically about how a moon helps a planet in producing its magnetic field or magnetosphere.
A magnetosphere is the magnetic field produced by a planet that repels a certain amount of the sun’s solar radiation, allowing us to keep a breathable atmosphere as well as keeping us from being bombarded by high levels of cancer-causing radiation. Ours is caused by the molten iron core of the planet. For comparison, Venus has only an induced magnetic sphere, created by the way the solar radiation interacts with its atmosphere. Mars has a magnetosphere approximately 1/40’s the strength of our own. It is believed that Venus’ core has solidified keeping the iron core from producing a magnetic field and that at least part of Mars’ core is liquid, but less than earth’s. This less-liquid core would not produce as strong of a magnetic field as our own planet.
The questions is, “Why is Earth’s core liquid, the core of Venus solid, and Mars has a semi-liquid core?” Here’s where my theory comes in: the directional gravimetric pull of our Moon is what keeps our core liquid. Specifically, it is the fact that the Earth is pulled unevenly by our Moon one way and the Sun from another that has kept our core from solidifying.
Contrast that with Venus and Mars. Venus has no moon and thus its has only one significant source of gravity being exerted on its core: the sun. Now that its day is slightly longer than its orbit, the directional gravimetric pull on its core is a near constant, generating no friction, no heat and thus no magnetic field. Mars’ moons’ lack of size (and thus lack of a significant gravimetric pull on the planet) can best be summed by Andy Weir in his book, The Martian when he was talking about how much light the moons reflect back to the surface at night, “Phobos gives me some moonlight, but not enough to work with. Deimos is a little piece of crap that’s no good to anyone.” These small celestial bodies are so small they provide some pull on the planet’s core, but not nearly as much as our Moon does for our homeworld. This means that the smaller gravimetic pull on the core does not produce as much heat and friction, meaning the core has somewhat solidified.
Contrast that with Pluto. We do not yet know if the far away rocky dwarf world has a magnetic field or not. However, we recently learned that it probably has an ocean of liquid water beneath its surface. This is obviously caused by the pull of its moons on the planet. Combine that with the fact that it is described as a “real world with diverse and active geology,” could be an indication that the gravimetic pull from the moons could affect the planet’s core, generating a magnetic field. If that is the case, it would be Charon pulling in one direction and its other moons (Nix, Hydra, Styx, and Kerberos) providing additional gravimetric pulls that keeps Pluto’s core molten. Should this be true, a base could someday be established on Pluto, one that requires keeping the base warm and breathable but does not require solar radiation shielding.
Ultimately, what does this mean and how does this help us? If this theory should be accurate, it might be worth an investment to redirect a sizable asteroid from the asteroid belt and place it in orbit around Mars. Over the course of a century or more, the planet’s core would remelt and increase the strength of Mars’ magnetic field, allowing for widespread terraforming of the planet, and letting humans and plants to eventually to live on the planet without special gear protecting us from the sun’s harmful radiation.