For centuries novelists have written about humans living and working on the moon. One of my favourite science fiction novels is “A Fall of Moondust” by the British author Arthur C Clarke (1917-2008). It was written in 1961, before man had ventured into space and when we knew very little about the Moon’s surface, but set in the 2050s. In the novel the Moon has been colonised, and it is visited by tourists from Earth. One of its attractions is a cruise, in a specially designed boat, across one of the maria, or lunar seas, filled with an extremely fine and very dry dust which flows like water.
Arthur C Clarke -the author of “A Fall of Moondust” Image provided by Amy Marash
Why would we want to colonise the Moon ?
There are many reasons for building permanent colonies on the Moon. I have listed a few below which I think are the most important.
- To ensure the continuation of humanity. One reason, which applies to colonising space generally not just the Moon, is that while the human species is restricted to life on a single planet it is vulnerable to extinction caused by natural or man made disasters. If humans could live in a self supporting colony on the Moon, then this would provide a Plan B to allow the continuation of our species.
- To spread civilisation to other places. Since humans first evolved, they have constantly sought new territories. It seems to be almost a biological imperative to find other places to live. There are not many uninhabited places on Earth, so humans may one day extend their civilisation not only to the Moon but also to other places in the solar system such as Mars and the moons of Jupiter and Saturn.
- It is relatively easy to get to. Compared to Mars, the next most likely candidate, the Moon is much closer to the Earth. The Moon is on average 384,000 km away from Earth, whereas Mars at its closest approach is still around 60,000,000 km away. It is therefore easier, and therefore cheaper, to reach.
- To stimulate the economy. Despite the enormous cost, building bases on the Moon will give a huge stimulus to the Earth’s economy and there will be many jobs created in high technology industries. There may well be spin-offs that we are not yet aware of, in the same way that the Apollo programme in the sixties and early seventies led to huge technological developments unconnected to space travel such as improved kidney dialysis equipment.
- There would be no biological impact. The Moon has no indigenous lifeforms which could be damaged by contact with humans. This is not true of the few uninhabited areas of the Earth, like Antarctica.
- To exploit resources. In the longer term it may be possible to exploit the minerals found on the Moon, including a rare form of helium called helium-3. This is more common on the Moon than the Earth and could be used to generate nuclear power, without the radioactive waste produces by conventional uranium-based reactors. In reality, there are still huge obstacles to doing this. The concentration of Helium-3 found in moonrocks is still very low and it may never be economically viable to extract it . Another point is that although Helium 3 could, in theory, be used to generate clean energy in a nuclear fusion reactor, no one has yet found a way of doing this.
Even compared to the most extreme places on Earth, the Moon is a very harsh environment and there are huge challenges to be faced in building a lunar colony.
- No atmosphere. The Moon has no atmosphere so a human would need to wear a space suit or they would be dead within minutes. Death would come not only from a lack of oxygen but also from the fact that any exposed fluids in their tears, saliva and even inside their lungs would quite literally boil away!
- Deadly radiation. The Moon has almost no magnetic field to shield the surface from cosmic rays from space. There is also no atmosphere, so other deadly radiation such as X-rays can get to the surface and cause damage to human health. When they left the protection of the Earth’s magnetic field, the Apollo astronauts kept seeing flashes of light even when they were inside their spacecraft with their eyes closed. This was due to cosmic rays passing through the wall of their spacecraft, and into their bodies, including their eyes. When the rays hit their their retinas, the light sensitive area at the back of their eyes, flashes of light were visible. Exposure to cosmic rays and other forms of harmful radiation greatly increases the risk of developing cancer.
- Extreme variations in temperature. The Moon rotates much more slowly than the Earth. On the Moon there are 15 days of daylight followed by 15 days of darkness. This, coupled with the lack of an atmosphere which would help to hold heat at night, means that the surface of the Moon is exposed to extreme variations in temperature. At the Moon’s equator over a 30 day period, the temperature ranges from +130 degrees to -140 degrees Celsius.
- Risk of meteor strikes. On the Earth, meteorites with a mass of around a ton or less burn up in the Earth’s atmosphere before they hit the ground. On the Moon there is no atmosphere in which this can occur, so anything which is attracted by the Moon’s gravity will hit the surface. Because meteorites move so fast they have a large amount of energy and can therefore do great deal of damage. A tiny pebble-sized lump of rock weighing only 10 grammes but travelling at 100,000 km an hour would have the same energy as a huge 10 tonne boulder travelling at 100 km/h (63 mph), and if this were to hit a moon base the results would be catastrophic.
For these reasons, I believe that a moon base would be better built underground where it would be shielded from the aforementioned radiation, meteorite strikes and extreme swings in temperature.
An Underground Moon-base
Another factor to consider is the long term impact of low gravity on the human body. This has never been studied before, although studies have been carried out in zero, rather than low, gravity conditions, primarily on astronauts who have spent time on the International Space Station (ISS).
Astronauts in zero gravity aboard the International Space Station -Image from NASA
When astronauts spend time in zero gravity their muscles weaken because they no longer have to support their weight. For this reason, astronauts in the ISS spend a great deal of time exercising to try and minimise the loss of muscle strength. Also, in zero gravity the body does not need to have strong bones for support. Astronauts’ bodies lose bone matter at the rate of 1.5% per month. After a year in space an astronaut would have lost roughly 20% of their initial bone mass, greatly weakening their skeleton. The minerals lost from their bones are excreted in their urine, which can give rise to kidney stones. After returning to Earth from a long space mission, it can take several years for bones density to return to normal, and astronauts may run the risk of osteoporosis in later life.
Although there is some gravity on the Moon, many of the negative impacts of zero gravity would surely occur, albeit to a lesser degree. I think it is highly likely that there would be loss of muscle and bone density if people spent long period of time there. One solution to prevent long-term damage might be for people to be attached to heavy weights so that they would weigh the same as on Earth. What is also unclear is how the development of young children would proceed. Would a child born and brought up on the Moon have weak muscles and thin bones, which would mean that they would never be able to live on Earth?
The International Space Station – Image from NASA
The International Space Station, pictured above, orbits the Earth less than 500 km above the surface. It normally holds only six astronauts and is the most expensive single object ever constructed, costing around $150 billion in 2014 dollars. It costs around $5 billion a year to run. All consumables such as food and water have to be brought up from Earth at great cost.
Building a large moon-base in which hundreds of people could live and work would undoubtedly cost far, far more. I would expect that the costs would be in the trillions of dollars. It would be too expensive for any single nation to afford and its costs- and benefits – would need be shared among all the countries of the world.
The moon-base would have to be as self sufficient as possible, because getting supplies from Earth would be so expensive. It might use the energy from sunlight to grow plants to produce food and oxygen, so that food would not need to imported from Earth. Water is also in very limited supply on the Moon. Although there are small deposits of ice in areas which are in perpetual shadow, such as the bottoms of craters, this would have to be strictly rationed and recycled.
Given the costs and complexities involved, I would predict that a large moon-base will not be built for at least one hundred years.
Updated 7 May 2020