Image courtesy TNT

Falling Skies: The Science Behind the Fiction – Wireless Moon Power

The end of Falling Skies’ fourth season pivoted on destroying the Espheni’s power source so that our grubby fighters might have a chance at winning the war. The problem with that plan was that the power source was on the freaking moon and I’m pretty sure not even Dai, were he still alive, could hit a target at that distance, much less find a gun that could shoot a bullet a quarter of a million miles.

The idea of harvesting helium-3 from the moon, converting it to power, then beaming it back to Earth to power the Espheni war machine might sound like complete science fiction, but the basic science behind it is sound. What follows is my mostly-uneducated summary of current Earth technology to try and show that what the Espheni were doing could (almost) be done with existing human tech.

I’ll be covering the reason for the source fuel, helium-3, and a way to beam that energy all the way back to Earth. But I’m also going to touch on Pope’s Faraday suit, which is the most grounded (pun intended) bit of science used in this scenario.

Image courtesy TNT

Why Helium-3?

First, let’s start off with what helium-3 actually is. It’s a non-radioactive isotope of “regular” helium that contains 2 protons and 1 neutron instead of the usual 2 protons and 2 neutrons. The missing neutron means helium-3 has a spare proton that gets released during a fusion reaction. These spare protons are where the energy comes from during the reaction. If helium-3 fusion reactions were commercially feasible, not only would it provide clean, safe power, but the energy produced would come directly from the reaction itself.

Today’s traditional nuclear power plants use fission reactions which create heat. That heat is then used to boil water which is then used to spin a turbine that generates electricity. The actual method of generating electricity is still very old-fashioned, we’re just using the heat from a nuclear reaction to boil water.

A helium-3 reactor, on the other hand, would cut out the middleman (boiling water turning a turbine) completely. That free proton can be converted directly into electricity with a currently estimated efficiency of 70%. Compare that to the most advanced solar cells in existence that clock in at under 45% efficiency and are very expensive, while the average efficiency of most solar panels sold are only in the 10-15% efficiency range. So if helium-3 reactors were commercially viable it would be a staggeringly efficient and ridiculously safe method of generating energy.

 

Okay, cool, but why the Moon?

Helium-3 is extremely rare on Earth. In fact, it would be easier to find an honest politician than a helium-3 isotope. The surface of the moon, however, seems to be lousy with the stuff by comparison. A number of larger nations and organizations, NASA included, have plans to mine helium-3 from the moon, though all those plans are probably decades away if not longer.

So the reason the Espheni chose the Moon as a power base is because it’s fairly rich in helium-3 and Earth is not. Plus, you know, it’s harder for those pesky monkey people to blow it up if it’s on the Moon. Or so they thought …

 

Getting all that power back to Earth.

We mere humans have considered actually trucking the helium-3 all the way from the Moon back to Earth, but that’s pretty inefficient and kind of rains on helium-3’s high-efficiency parade. Another proposal is to beam the energy back home. While it was never explained in detail, the Espheni’s beaming of “wireless electricity” back to Earth could have used a microwave beam, which has been done on a smaller scale.

Image courtesy TNT

If you’ve got an electric toothbrush or maybe one of those charging mats for your cell phone, you’re already using wireless electricity. It’s just the distances are very, very small compared to going to the moon, or even going to the bathroom. The charge in those devices is done through simple electromagnetic induction which works great, but you have to almost be touching the power source. The Moon is much harder to touch.

And that’s what makes a microwave energy beam a good candidate for the long journey from Moon to Earth; it can be transmitted over very long distances and doesn’t require the receiving device to be almost touching it. But remember, this is a beam of microwaves, not electricity, so it would have to be captured and converted to be useful.

For that, the current technology, at least on Earth, is to use something called a rectifying antenna, or rectenna. A rectenna converts the microwave energy into useful electricity. The idea of producing energy on the moon and transmitting it back to Earth has already been proposed by scientists, so it’s not an idea that’s, um, alien to us. The critical difference between this proposal and what the Espheni did is our lowly human plan was to use a buttload of solar panels on the moon and not some cool helium-3 fusion generator.

 

How Faraday cages, or suits, keep you safe from all that power.

When Pope donned the Faraday suit to climb the fence-o-death he might have looked like a reject from Monty Python and the Holy Grail, but the science behind his protective suit is sound. A Faraday cage is really nothing more than a hollow, conductive container that sends electrical charges around the outside of itself, protecting whatever is inside. It’s a very low-tech, but very effective deflector shield against electrical discharges. The first Faraday cage was invented by English scientist Michael Faraday in 1836, so this technology is really old school.

Image courtesy TNT

Airplanes and automobiles are common, everyday examples of Faraday cages. Microwave ovens act as a sort of reverse Faraday cage by keeping the microwave radiation inside the oven to cook your food instead of letting it leak out to cook your eyeballs as you hungrily eye your slowly rotating dinner through the glass door.

Heck, you can wrap something in aluminum foil and it becomes a Faraday cage. So rest assured your leftovers are protected from lightning strikes, assuming you worry about that sort of thing. If you do, you should probably see a professional.

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