OK, let’s see if we could start with a much smaller habitat, but still big enough to grow most of its food. I assume a two cylinder habitat with 300 metre radius (just big enough to provide 1g artificial gravity without revolving too fast for comfort), and 500 metres long, which would house around 1,000 people. I am assuming that it would be assembled from parts and resources from earth, apart from lunar regolith for soil. I am also assuming that it is placed in low earth orbit, which reduces the need for radiation protection as it is within the Van Allen belts. A thin outer sheet of aluminium would do (as in the ISS) and an inner plastic plate.
Even so, 1.56 million tons need to be transported from Earth, as shown below, and the costs of such transport is very high.
Now the components and assembly of such a habitat, and transporting lunar regolith as soil, would cost hundreds of millions of dollars, but that is minor compared to the cost of transporting such a large tonnage above into even low earth orbit (LEO). Even at $100/kg launch costs, the cost of transporting the parts for such a habitat from Earth would exceed $150 billion, more than my estimate of a large habitat built in long run space conditions which would house 200 times more people.
Moreover, there seems no chance of getting launch costs down to such a low level in the near future. It needs to be a long term objective (or even lower) just to get people long term into space, but then potential low cost solutions (such as the spaceplane/skyhook combination suggested in earlier posts) need high volume to be economic, to cover high capital costs, and you won’t get high volume until costs are low … classic “chicken and eg” dilemma. It would cost over $1 billion to develop Skylon, we are probably stuck with incremental improvements to rockets for now (such as recovering first and second stages).
Not only are the above costs way too high, this approach does nothing to develop space manufacturing. There is a better route, to be discussed in the next post.
Note that cumulative costs (launch, assembly, maintenance) of the International Space Station is over $100 billion to date – and that only weighs 420 tons, and the living area is barely the size of a suburban house.
Costs are acceptable, but fresh air isn’t free