The Moon is the Earths only satellite, and so far the only foreign body, that humans have stepped on with their feet. Because of its close proximity to the Earth, the Moon will be most likely the first object on which humans have permanent settlements. Many states have expressed their interest on having a permanent moon base, so the colonization of the Moon might happen sooner than we might imagine.
Moon has a diameter of about 3 500 kilometres, which is about 27 % of the diameter of the Earth. The mass of the Moon is only about 1,2 % of the mass of the Earth. Gravity experienced on the surface of the Moon is about 17 % of that experienced on Earth. Of all the moons in the Solar System, the Moon is the second most dense.
The Moon has a core, that consists mostly of iron, and is also partially liquid. The Moon has a thick mantle on top of its core, that consists mostly of silicate rock and iron. The crust on the top of the mantle consists various elements, for example silicates, lime, aluminium and iron oxides.
Orbit and rotation
Physically, the Moon orbits around the Earth in approximately 27 days. Because the Earth orbits around the Sun the same time, one phase of the Moon lasts around 30 days. Like most other moons, the Moon is tidally locked to the Earth, so the same side is always positioned towards the Earth.
The properties of the crust are well known, because we have brought samples back from the Moon. Approximately half of the crust is silicon oxides. In addition, the crust contains a lot of aluminium oxide, lime oxide, iron oxide and magnesium oxide, with smaller concentrations of titanium oxide and sodium oxide.
Surface of the Moon contains a lot of dark oceans, that are created by ancient volcanoes. They are essentially covered by lava. Surface of the Moon has also hundreds of thousands of craters, that have been developed during billions of years by meteorite strikes.
Liquid water can’t exist on the surface of the Moon, because it would get decomposed by radiation from the Sun, and the hydrogen vapour would disappear in to the space. However, it is possible that the Moon contains small amounts of water. Frozen water might exist quite close near to its surface, which could be used by explorers.
The Moon does not have an atmosphere. It is basically a vacuum, so the colonisers would have to use a pressurised suit to explore the Moon. There’s a bit of dust floating around, which is raised to air by small particles that hit the surface of the Moon.
Temperatures on the Moon vary widely, depending whether it is the day or the night. The temperatures at the equator are about -50 °C on average, with the lowest temperatures being about -170 °C and the highest temperatures about 120 °C. Temperatures in the craters can be very low, and one of the coldest temperatures ever recorded, -245 °C, was recorded near the north pole of the Moon.
We already have the methods to travel to the Moon. However, humans have not visited the Moon for decades, so the technology should be updated to todays standards. It takes a couple of days to travel to the Moon, which is very comfortable to humans. With current technology, price is a problem, as transporting one kilogram of material to the Moon costs millions of dollars.
Its way more easier to travel from the Moon to the Earth, than vice versa. If a large base is built on the Moon, a space elevator or some other system could be built, that would allow inexpensive trave from the Moon to the Earth. The Moon could be used for harvesting resources, and the resources could be transported back to the Earth rather cheaply.
There are multiple ways to build permanent habitats on the Moon. The first habitats will probably be rather inexpensive and light modules, that can be covered with the soil. The soil can be transformed to a glass-like structure with radiation. Its important to protect surface habitats from micrometeorites, which could be done by building an light artificial magnetic field over them, or placing them in secure places inside craters.
It would be also possible to build the bases under the surface of the Moon. Underground habitats would be effectively protected from the radiation and micrometeorites. Remotely controlled robots could be sent to the Moon, which would create a ready base for humans. Digging the soil can be tricky, so it might also require the help of manual human labour.
One important thing to consider is the location of the bases. The place should have an easy access from and to the Earth, and it should also include valuable resources and interesting objects for scientific studies. If the base were to use solar energy, it should be readily available. Ideally it would also have a direct line of sight to the Earth, to ensure efficient communications without satellites. The temperatures should be somewhat stable, with not too low nor high temperatures.
NASA has suggested a place that is near the lunar north pole, where the temperatures are somewhat stable, averaging around -50 °C. The location has places nearby, where the Sun shines almost all the time. There are also interesting places near the lunar south pole, and equator would be interesting location because of its larger resources of helium-3.
There are multiple ways to satisfy the energy needs of a moon base. With current technology, it would be most feasible to use solar energy or small fission reactor. The fuel for the fission reactor could be brought from the Earth. If we were to use solar energy, and the selected location does not have constant sunlight, an efficient method to store energy should also be considered.
If fusion reactor technology will be developed to work, they might be very useful on the Moon. The Moon has large resources of helium-3, which can be used as a fuel in fusion reactors. This means that a Moon base would be very independent and efficient with its energy.
One of the upsides of the Moon is its close distance to the Earth, which can be also seen in the short communication delays. Messages between the Moon and the Earth have a round-trip time of under three seconds, which means that the settlers would be able to use real-time communications, such as video calls, although with some delay.
Because of the small delay, robots controlled from the Earth could also be used on the Moon, which isn’t possible with other objects in the Solar System. Therefore, a lunar base could be built with robots, without the need of autonomously working robots.
If bases are created on the Moon, they should preferably also be economically viable. Factories could be established on the Moon, and they could mine resources and refine them before transporting them back to the Earth. In the future, because of possible fusion reactors, helium-3 might be a very important resource, and moon has large reserves of it.
There are some theories that play with the idea of terraforming the Moon, but in practice it would be very hard. First of all, we should create an atmosphere, that wouldn’t disappear to space despite the Moons small gravity. Instead of nitrogen, we could use heavier gases, such as xenon or krypton as a buffer gas. However, these gases only exists in small amounts, so finding them and transporting them to the Moon would be quite challenging.
A lot of water should be brought to the Moon in order to create oceans and working climate. Hydrogen and oxygen are vast resources in our Solar System, but transporting them to the Moon might be an impossible task.
The Moon has long days and long nights, so we should be able to shorten them in order to keep the temperatures in control. This could be done with large installations of solar mirrors and shades. However, with artificial lightning and heating systems, this wouldn’t be necessary.
The Moon is one of the most important objects for human space colonization, and its probably going to be one of the first places that will be settled. Its close to the Earth, and we already have the technology to travel there. However, the costs of travel are still quite high, and harvesting the resources of the Moon is still a challenge.
Many states have planned lunar bases, and its probably only a matter of time until the first base on the Moon will be established. The first lunar bases will probably be quite small, but with time and technological development, resources on the Moon can base used to provide for the mankind.