Anyone who grew up with the Apollo moon launches in the 1970s, along with the movie "2001: A Space Odyssey" (which premiered in 1968), was left with the impression that there would be colonies on the moon any day now. Given that it's now more than 30 years later and there's been no significant progress, it's safe to assume there won't be a moon colony any time soon. But it's still a tantalizing thought. Wouldn't it be cool to be able to live, vacation and work on the moon?
Let's say we did want to colonize the moon. There are some basic needs that the moon colonists would have to take care of if this were any sort of long-term living arrangement. The most basic fundamentals include:
It would be ideal to get as much of these resources as possible from the moon itself, because shipping costs to the moon are unbelievable -- something on the order of $50,000 per pound. Just one gallon of water weighs about eight pounds, so it costs $400,000 to get it to the moon! At those rates, you want to carry as little as possible to the moon and manufacture as much as you can once you get there.
Obtaining breathable air, in the form of oxygen, is fairly easy on the moon. The soil on the moon contains oxygen, which can be harvested using heat and electricity.
Water is trickier. There's now some evidence that there may be water, in the form of buried ice that has collected at the south pole of the moon. If so, water mining might be possible, and it would solve a lot of problems. Water is necessary for drinking and irrigation, and it can also be converted to hydrogen and oxygen for use as rocket fuel.
If water isn't available on the moon, it must be imported from Earth. One way to do that would be to ship liquid hydrogen from the earth to the moon, and then react it with oxygen from the moon's soil to create water. Since water molecules are 67 percent oxygen and 33 percent hydrogen by weight, this might be the cheapest way to get water to the moon. As a side-benefit, the hydrogen can react with oxygen in a fuel cell to create electricity as it creates water.
Moon Colony Resources
Food is also a problem. One person eats about 450 pounds of dehydrated food per year. A whole colony of people would require tons of food. The first thought that anyone on Earth would have is, "Grow the food on the moon." We think that way because here on Earth, chemicals like carbon and nitrogen are freely available in the atmosphere, and minerals are freely available in the Earth’s soil. A ton of wheat is made up of a ton of carbon, nitrogen, oxygen, hydrogen, potassium, phosphorous, and so on. To grow a ton of wheat, you'll have to import all the chemicals not readily available on the moon. Once the first crop is in, and as long as the colony's population is stable, then the chemicals can be reused in a natural cycle. The plant grows, a person eats it, and the person excretes it as solid waste, liquid waste and carbon dioxide in the breath. These waste products then nourish the next batch of plants. But you still have to get tons of food or chemicals to the moon to start the cycle.
In the shelter category, it's likely that the first shelters will be inflatable structures imported from Earth, but a lot of research has been done on the possibility of building structures from ceramics and metals created on the moon.
Power on the moon is an interesting challenge. It would probably be possible to manufacture solar cells on the moon, but sunlight is available only part of the time. As mentioned previously, hydrogen and oxygen can react in a fuel cell to create electricity. Nuclear power is another possibility, using uranium mined on the moon.
With all of this information, you can begin to see why there's not a colony on the moon right now -- it's complicated! But let's imagine that we wanted to create a 100-person self-sustaining colony on the moon. Let's further imagine that, to start the colony, the following was shipped to the moon per person:
- The person him/herself -- 200 pounds
- A starter pack of food (or chemicals to grow food) -- 500 pounds
- Initial shelter and equipment -- 1,000 pounds
- Manufacturing equipment -- 1,000 pounds
That’s approximately 3,000 pounds per person and 300,000 pounds for the colony. When you realize that the space shuttle orbiter weighs 165,000 pounds without fuel, and you understand that the 100 people are going to live their entire lives on the moon off of the materials found in just two space shuttle orbiters, you realize how extremely optimistic this weight estimate is. At $50,000 per pound, that's $15 billion just for the shipping costs. By the time you factor in design, development, materials, training, people and administrative costs, as well as actual amounts of materials that have to be sent, not to mention the time and money that's been invested just to get the International Space Station into low-Earth orbit, you can see that even a small colony on the moon would cost hundreds of billions, if not trillions, of dollars.
Maybe next year...