Getting All Charged Up
Remember how we said that the plants that we needed to make our air
needed lights during the lunar night? That's just one example of
how we need to use electricity on the moon. We also need to use electricity
to get water out of the air, to help control the temperature of the moonbase,
and for all of our lights, computers, robots, and other equipment.
During the lunar day, the easiest way to get electricity is directly from
the sun using solar cells. Of course, during the nighttime on most
places on the moon this doesn't work, so a different kind of power source
is needed.
Nuclear Power or Solar Power
Right now we're only going to talk about two of the kinds of power sources that can be used. One of them is nuclear power. Nuclear power is able to generate a lot of electricity for a moonbase. In fact, the moon is full of a special kind of helium called helium 3 or just He3 for short, that some scientists believe will provide the moon and the earth all of the nuclear fusion power both planets will ever need. That would be really great, but that technology isn't working just yet, so the nuclear power we're talking about for our moonbase would be nuclear fission power, just like the atomic reactors on earth. A reactor would be nice because it can be easily controlled or fixed by people on the moonbase (because its close by), and because it generates a whole bunch of power. There are a bunch of problems with an atomic reactor on the moon too. The two biggest problems are that an atomic reactor would have to be launched up to the moon from earth, and most people think the nuclear fuel in an atomic reactor is very dangerous. Big atomic reactors are really heavy, and you'd need a really big rocket to launch one to the moon (or a lot of little rockets if you sent the reactor to the moon in pieces). If the rocket crashed during lift off, a lot of nuclear fuel would be scattered all over the ground, and some of it might even burn up in the air. This big problem with atomic reactors makes many scientists worry about ever launching an atomic reactor into space.
Another way to get electricity to the moonbase is to have some solar cells on our moonbase for electricity during the solar day, and another group of solar cells somewhere else during the solar night, for instance someplace where the sun is still shining. For instance, if some solar cells were put on the other side of the moon and wires run from those solar cells to our moonbase, then we could have electricity all the time! Of course, we would also have a big problem with all the wire we would have to string between the moonbase and the solar panels on the other side of the moon -- we might need an extension cord as long as 5500 km/3418 miles to go from the moonbase to the solar panels on the other side of the moon. Of course, in most cases, that's too much wire.
There is another way to move electricity from one place to another without using wires at all, and there is a really good place to get power that gets sunlight all the time. That place is in space, in a special orbit above the moon. And the way to move electricity without wires is by using the electricity to make microwaves, and then sending the microwaves where you need the power. Microwaves are a special kind of super high radio frequency energy that can be very accurately pointed in any direction that it is needed. That is why microwaves are used for things like radar. Microwaves also carry a lot of energy, that's why microwaves are used in microwave ovens. So a special satellite orbiting over the moon uses solar cells to make electricity out of sunlight; then it uses that electricity to make microwaves and sends those microwaves to a place near our moonbase.
The next part of the trick is to turn the microwaves back into electricity.
This is done with a big area on the moon covered with small antennas that
kind of looks like a field of antenna trees. The antennas turn the
microwaves back into electricity, and the rest of the work is pretty easy.
There is one last trick I will talk about here, and this only works
if the moonbase is near the south pole or north pole of the moon.
This also uses solar energy, which can be turned into electricity with
solar cells. Maybe you've heard that scientists think there is ice
hidden in the bottom of craters on the south and north poles of the moon.
These craters are special because the sunlight never goes into them.
Why? Because on the lunar poles, the sun is always very low in the
sky. If the sun was high in the sky, the sunlight would quickly melt
the ice inside the craters. The interesting part for our energy needs
is that the sun never really sets completely either. Just as there are
craters near the lunar north and south poles, there are also mountains
or high spots near the poles too. The high spots are different from
the craters because sunlight almost always shines on these high spots.
So if we put our base on one of these high spots (or put mirrors on one
of these high spots and reflected the light to our moonbase, or put solar
cells there and sent electricity to our moonbase) we would never run out
of power! But remember this trick only works if we put our moonbase
at one of the lunar poles.
Keeping Cool and Keeping Cozy
Temperature control is the next big thing to worry about. The solution is something us rodents are pretty used to, we decided to build our moonbase in a hole in the ground! Not really, what we actually decided to do was to dig a wide ditch on the lunar surface, then build our moonbase down in the ditch, and then cover the moonbase up with the dirt we had dug out of the ditch. That way the moonbase would be buried halfway underground. Rodents and people figured out a long time ago that caves and holes in the ground were nice places to live. The reason for that is that the temperature under the ground doesn't change much, even when the temperature above ground changes a lot. On the moon, the ground temperature is actually pretty cold, always around 35° F/2° C which is like a winter day on earth, but that's OK, because all of our plant lights can warm up the inside of the moonbase so it stays nice and cozy, day or night.
So that's the plan we came up with to live on the moon. Now all we had to figure out was how to get there...