Lunar Mining and Energy: Powering Sustainable Moon Colonies

On July 20, 1969, Neil Armstrong's historic first step on the Moon marked humanity's greatest leap into space exploration. This monumental achievement opened the door to a new era, an era where humanity would venture beyond our common home into the unknown of space. Yet as NASA lost government interest, human beings have now not stepped foot on the moon for over 50 years. But now, 50 years later, with the rise of commercial space travel and new geopolitical rivalry, the Moon has again caught our eye. The Moon has captured our attention as a way to explore and to expand our civilisation – and it now seems that we are headed there to stay. This is part one of a three part series on our growing lunar economy. 

 

This article will focus on mining resources from the moon and powering lunar settlements, and in the following articles we will look at how our life will look on the moon as well as agriculture and biodomes on the moon.

 

Lunar Mining and In Situ Resource Extraction

Various government programs, most notably NASA’s Artemis program, as well as private space enterprises have their eyes set on the moon, yet we must consider how lunar colonies will sustain themselves so far from Earth. It is far too expensive to be sending large loads of materials to the moon, and if anything breaks, there would be a substantial wait – often far too long. So how will we solve this problem?

 

The proposed solution is ISRU (In Situ Resource Extraction), which involves mining materials already existing on the Moon to build what we need to support our lunar settlements. There are two main resources of the moon of value to our colonies: regolith and lunar ice. 

 

Regolith is like the soil of the moon (although it is not living like Earth soil), it consists of remnants of former asteroids and meteorites which have collided with the moon and turned into rock fragments and dust. The value in this regolith comes from its constituents – it consists of roughly 40% oxygen, and the rest is a variety of metal alloys, most notably silicon, iron and aluminium. This oxygen would be highly important for lunar colonies, not only for life support, but for rocket fuel. Rocket fuel typically consists of liquid oxygen and liquid hydrogen, so when the oxygen is separated from the metals (via electrolysis) and liquified it can be used for lunar fuel depots. The remaining metal alloys can then be used in a diverse range of building applications. The proposed idea for constructing and repairing settlements on the moon is to bring a 3D printer to the Moon and use concrete (made from the metals in the regolith) as the material to construct buildings and other important machinery and tools.

The latter resource of value on the Moon is lunar ice, which is why upcoming missions are planned to go to the Moon’s south pole. Like regolith, lunar ice is believed to come from asteroids and meteorites colliding with the Moon. Most of this ice would have been evaporated by the extreme heat (up to 120° C) the Moon receives from sunlight, yet there are some areas of the moon which are perpetually dark. This perpetual shadowing leads them to remain extremely cold (colder than -220° C) which allows the existence of ice. This ice will be invaluable as it would otherwise cost from $2000-20 000 to send one kilogram of water to the moon. So when combined with recycled urine, lunar ice would allow for much cheaper access to water. But this is not the only use of lunar ice. It can also be used as a rocket fuel by separating the water into hydrogen and oxygen and then liquifying it (like the oxygen from the regolith). After being liquified it can then be stored in a lunar fuel depot to refuel any spacecraft stopping at the Moon. There is also no worry of running out of this fuel for a long while as deposits are estimated to accumulate to tens or hundreds of millions of metric tonnes (for context, Saturn V rockets sent to the Moon only required 2,400 metric tonnes of fuel). However, there are significant challenges with gathering this lunar ice. As it would be at a temperature of less than -220° C, it could not be extracted by humans. The ice will thus have to either be obtained by robotic systems able to withstand the extreme cold or by some other means of vaporising (likely with focused sunlight) the ice and capturing it as a gas.

 

As well as these interesting resources, the Moon is also believed to have large deposits of Helium-3 (which is quite rare on Earth). This is generally considered a better alternative to deuterium in fusion reactors due to it having less radioactive byproducts as well as likely being easier to extract energy from. Although not of much use now, it will be needed by future fusion reactors – both on and off the Moon.

 

Lunar Energy Production and Distribution

As the Moon will not be connected to the Earth’s electrical grid, it will need its own sustainable and reliable energy sources. The two primary contenders are nuclear and solar. NASA is currently working on a project called Kilopower, which aims to produce a set of reliable, powerful and compact fission reactors. Fission reactors are highly desired in early development of sustainable lunar colonies as they are reliable and can operate around the clock, particularly in perpetually dark craters or during the almost 15-day lunar nights. As well as this, the reactors only need to be small-sized and can hence be transported to the Moon with minimal hassle. Their small size is due to the limited power they need to produce and hence the small quantities of uranium required to fuel them. The systems NASA is asking companies to design would provide at least 40 kilowatts of power, enough to continuously power 30 households for ten years. Studies have shown that this level of power would be adequate for a crew of 4-6 astronauts.

 

Although lunar nights are very long and solar cannot be relied on as the sole source of power, there is still significant potential for their usage. Lunar days last for 14 days, meaning that there will be long periods of open access to sunlight (and some areas close to the south pole have near-constant sunlight). There will also be an increased solar panel efficiency of around 3% compared to Earth due to the lack of atmosphere on the Moon. Yet these solar panels will demand greater requirements than those on Earth due to the extreme lunar conditions. Powerful cooling systems will have to be in place to keep the solar panels from overheating as they will be exposed to extreme solar heat for around 14 Earth days. As well as this, they will need advanced batteries to store the energy during the long lunar nights.

 

Yet generating energy for lunar colonies is not the only concern as the power will also have to be distributed throughout the settlement. Lunar microgrids will be similar to electrical grids on the Earth, yet will require more advanced technologies such as high-efficiency DC distribution systems, resilient architecture and automation. In particular, there will have to be significant development into the automation systems to protect the grid from extreme conditions and fix arising issues somehow inaccessible to human astronauts. However, it will not be viable to have the lunar microgrid power the entire settlement as obvious restrictions will make it difficult to set up a grid to run across the entire area of operations. Operation sites further away from the main settlement, such as mining sites or solar panel sites, will have to have their own off-grid energy production. Major sites could have their own fission reactor, otherwise they would likely be powered by chemical fuel cells, such as hydrogen which could be gathered from lunar ice.

 

So it seems certain that settlement and habitation of the Moon will be invaluable to humanity's future in space exploration. Lunar mining may serve as highly useful for building the infrastructure to support the upcoming space economy. We know that many of the resources on the Moon are valuable and widely used in our Earth economy, and we also know that it is easier to rocket off the Moon than off of the Earth. Hence it is highly likely that the Moon may evolve into a commerce hub of the future space economy. Furthermore, ISRU and microgrids on the Moon will give us experience in building sustainable space settlements, and will be invaluable for exploration of Mars and beyond.