Question occurred to me when I started thinking about vacuum worlds and other places with no arable land trying to feed themselves:
Question: how much does a habitat cost? How much does it cost to build a city on the moon or dug into some asteroid, or to make space for agriculture on an airless world? We build and price ships, but we don't tend to look at how much it's costing to put a colony on some of these worlds that don't have free air for the taking.
Let's start with some comparisons. An acre of space is about 900 dTons. Modern acre of farmland costs around $3000 an acre now, closer to $2000 around the time MT was published. A modern four-story office building costs around $130-230 per square foot to put up, depending on where you're building, which makes it around $5.6 million to $10 million for the same amount of space.
For these purposes, we want something that will support people, but it doesn't have to move; we're looking at planetside and spacebased habitats, and planetside stuff won't be moving (unless you've got a specific idea for something strange and neat), so we won't add drives to the spacebased stuff.
CT doesn't give us a lot of insight. There's shipbuilding, but the environment costs are subsumed in the cost of a Stateroom. Could be workable but a lot of hidden assumptions like grav plates that a groundbased installation might not want to spend money on (altough it would certainly be nice to not bang your head on the ceiling every time you take a wrong step).
MT gives very detailed guidelines that might be used, if you mine that resource.
First, hull material:
Then, environment:
Nutshelling it, we're looking at Cr26,000 per dTon in the CT world and maybe Cr12,000 in the MT universe (half that if you're willing to live with local gravity or in a rotating structure). Ballparks it around Cr23 million per acre in CT or Cr11 million in the MT universe, which is roughly consistent with building a city, but tells me that trying to grow food in that situation is like building an office building and then trying to grow food in that, which is to say doable but - at 2000 to 5000 times the "land" cost of good ol' fashioned farming - it's very expensive food, even amortizing the expense over a long stretch.
Question: how much does a habitat cost? How much does it cost to build a city on the moon or dug into some asteroid, or to make space for agriculture on an airless world? We build and price ships, but we don't tend to look at how much it's costing to put a colony on some of these worlds that don't have free air for the taking.
Let's start with some comparisons. An acre of space is about 900 dTons. Modern acre of farmland costs around $3000 an acre now, closer to $2000 around the time MT was published. A modern four-story office building costs around $130-230 per square foot to put up, depending on where you're building, which makes it around $5.6 million to $10 million for the same amount of space.
For these purposes, we want something that will support people, but it doesn't have to move; we're looking at planetside and spacebased habitats, and planetside stuff won't be moving (unless you've got a specific idea for something strange and neat), so we won't add drives to the spacebased stuff.
CT doesn't give us a lot of insight. There's shipbuilding, but the environment costs are subsumed in the cost of a Stateroom. Could be workable but a lot of hidden assumptions like grav plates that a groundbased installation might not want to spend money on (altough it would certainly be nice to not bang your head on the ceiling every time you take a wrong step).
MT gives very detailed guidelines that might be used, if you mine that resource.
First, hull material:
CT hull material ends up costing Cr50,000 per dTon (assumes dispersed structure) for something that can withstand micrometeor hits as a ship's hull can.
Same thing in the MT world hits around Cr22,000 per dTon (hull frame plus factor-40 armor), and there are discounts if you go above 10,000 dTons: a 100,000 dT town of maybe 20-25,000 souls is half that. Starts heading up again after 300,000 dTons for some reason: a 1,000,000 dTon small city hits Cr14,700 per dTon. Something to do with the way they calculate the hull mass. Anyway, if you can shave hull down to 8 (a bit over 3/4 inch "soft steel") on the argument that it isn't moving anywhere, you can save quite a bit: Cr1400 per dTon up to 10,000 dTon, slides down to Cr1000 per for 100,000, Cr900 per for 1,000,000.
Best, however, is to mine out an asteroid or dig into the planet. Cr1000 per resulting dTon in the CT world, plus a bit to ship if you're moving an asteroid. A bit steeper in the MT world: Cr75 per cubic meter of hull, ergo the total hull, rather than of resulting space (why a tunnel costs more in a buffered planetoid is beyond me, but that's not the focus of the essay, though it might warrant a look over in errata), so Cr1265 per useful dTon (basing the comparison on the planetoid). MT's a bit more for mining than for the factor-8 hull, but you get a few feet of rock providing factor-50 armor to protect your habitat, well worth the cost when the solar flare hits.
Then, environment:
Ct offers three options. A crash couch - which presumably comes with air to breathe for at least a day - costs Cr25,000 for a half dTon. A small craft stateroom offering barebones long-term support for one person costs Cr50,000 for 2 dT. A full stateroom providing longer support for up to 2 persons is Cr500,000 for 4 dTons. So, Cr25,000 to 125,000 per person/dTon, depending on whether you'de just looking for air and gravity or would like the recycling plumbing, the plush carpeting, and the stove and washer/dryer thrown in. All that is powered en passant - it assumes you have a power plant, and a wee bit of that power is being diverted to life support.
MT runs Cr135 per dTon for lights and cliimate control, Cr4050 per dTon for the privilege of breathing useful air - puts it around Cr4,200 per dTon. Adding a comfortable definition of "up" adds Cr6750 per dTon but drinks power like a fish drinks water; we could content ourselves with local planetary gravity or centripetal acceleration. It all needs to be powered, and fusion plants are expensive beasts, but solar cells are reasonably cheap and reliable. (MT solar cells are magical beasties, producing many times more power than there is sunlight, but then MT life support systems seem to eat power like candy, so maybe it'll balance out for this issue).
Nutshelling it, we're looking at Cr26,000 per dTon in the CT world and maybe Cr12,000 in the MT universe (half that if you're willing to live with local gravity or in a rotating structure). Ballparks it around Cr23 million per acre in CT or Cr11 million in the MT universe, which is roughly consistent with building a city, but tells me that trying to grow food in that situation is like building an office building and then trying to grow food in that, which is to say doable but - at 2000 to 5000 times the "land" cost of good ol' fashioned farming - it's very expensive food, even amortizing the expense over a long stretch.
