Colonizing the Moon with GURPS Spaceships

[AlexanderHowl]

I was curious how much it would cost to set up a 10,000 person realistic mining colony on the moon within five years without superscience at TL9 using the rules from GURPS Spaceships (we will ignore the Spaceships 2 interface and transport numbers because they ignore certain realities of economics for ease of playability). In order to account for the psychological needs of the humans, we will need one open space per habitat. In order to account for the economic needs of the humans, we will need around 6,000 jobs.

The number that I am getting is around $1 trillion, and I was wondering if anyone would get a different number. Since we are looking at a realistic perspective, any interface crossing spacecraft probably needs a month of repairs and inspection after every mission, so please keep that into account. Also, please remember that people will bring luggage (~0.1 tons/person) and to account for required life support when going from Earth surface to Moon surface.

[Varyon]

Our final design for the colony would call for around 75,000 tons of Habitat, and an equal mass of Open Spaces. Note this is 1 person per cabin - low-ranking workers will probably be in bunks (4 to a cabin), while high-ranking managers will likely have large personal rooms (multiple cabins for a single person), and some cabins will actually be Establishments rather than living areas, so I assume this will all roughly balance out to 1 per cabin. The bulk of the work here will be mining raw materials and processing them into components to be shipped to orbital colonies and settled planets (including Earth). We’ll need a communication array of some sort. While it could probably safely rely on relays, let’s give it enough range to talk to Earth directly. Even a Level 1 array is good enough for that - at TL9, that’s a system for an SM+1 vessel, so would be only around 30 lb. Let’s boost that to 1.5 ton for a great deal of redundancy and some increased range (Level 5 array). Our colony needs armor to help protect against occasional meteor impacts and from radiation, but stone armor is functionally free, so we’ll just use however much of that we need (likely by simply burrowing into the moon). To reduce the number of impacts it has to tank, we’ll give it a 1.5 ton laser cannon (or 1.5 tons worth of smaller laser cannons, whichever is more effective) to blast whatever tries to slam into it. We’ll also need power, for our mining and factory systems. Fission is cheapest, but we’ll go with solar panels instead as those don’t require workers and are easier to manufacture on site (and less likely to cause excessive angst back on Earth). We also need somewhere to store our goods until they can be shipped out, but cargo holds are free. I’m not sufficiently knowledgable about economics to figure out what percentage of the inhabitants are involved in mining/production as opposed to support roles (like nurses, farmers, etc), and Spaceships gives no guidance on how many people need to work a Mining/Factory system to keep it running, so I’m just going to assign all 7,000* jobs to cover the workspace requirements. A 75,000 ton Habitat/Open Space system would be appropriate for a 1,500,000 ton vessel - we’ll go with SM+14 and increase by +1 SSR. An SM+14 system needs 300 workers**, so we’ll go with 500 here. That’s 1,000 of our 7,000 jobs simply in keeping the Habitats and Open Spaces working. The comm/sensor array and laser cannon(s) are small enough not to need workspaces, so we’ll ignore those. That leaves us with 6,000 jobs for miners and factory workers. That’s the same number of workers we’d need for 2 SM+17 systems, so we’re looking at 3,000,000 tons. We’ll need an equal mass of solar panel arrays to power it.

Now we need to know the ratio of factories to mining systems, which aren’t given anywhere. Using the speeds from SS1 (each ton of factory system produces $24k/day), each person working in a factory system produces $12M per day. Using the speeds from SS2 (each ton of factory system produces $1k/day), each person working in a factory system produces $500k/day. If our mining and factory workers average out to around Average wealth, they need to be paid $3600/month. If we assume 4 mining facilities are needed for each factory (my gut reaction here being “divide by 5”), this means our mining and factory workers are each producing either $2.4M or $100k each day, depending on what speed we’re using. Assuming 30 day months, subtracting out their pay, and rounding to two significant figures, that’s a net gain of either $14B or $600M every month - but note this doesn’t factor in how much it costs you to ship the goods to their destination.

That’s 75,000 tons ($1.5B) of Habitat, 75,000 tons ($10M) of Open Spaces, 1.5 tons ($60k) for a comm/sensor array, 1.5 tons ($150k) for laser cannon(s), 3,000,000 tons of solar panel arrays ($500B), 2,400,000 tons of mining/processing ($48B), 600,000 tons of factories ($600B). Grand total, not counting the free armor, we’re looking at 6,150,003 tons, and $1,149,510,210,000. Now we just need to figure out what it costs to get it there. We’ll leave out the cost of the comm/sensor array and laser cannon(s), since it’s pretty much a rounding error at this point.

Luna has resources, so it seems appropriate to build things there rather than building them on Earth and then shipping them there. Assuming you have things at a comparable relationship to how we end up at the end (40% not producing anything, but likely working the establishments, maintaining habitats/open spaces, etc), every colonist requires $150k of Habitat, $1k of Open Space, $50M of Solar Panel Arrays, $4.8M of mining/processing, $60M of factories, for a grand total of around 615 tons and $115M per colonist. Each colonist produces either $1.44M or $60k per day. Over the course of 5 years, that’s $2.592B or $108M. That means, if you had your initial crew work for the full 5 years and then send everyone else once everything was setup, you can say each colonist makes enough infrastructure for either 24 more colonists, or 1 more colonist. So, of your initial $1.15T, you actually need to only initially ship either $46B or $575B, and pay $6.5M worth of salaries (which is pretty much a rounding error). You can probably reduce this if you send everyone at once, but have 1/25 or 1/2 the colonists in hibernation chambers, then wake them up as their “section” is completed, allowing them to contribute to future work. That’s more complicated to figure out, however.

Note the above doesn’t count on the cost to ship things to the moon. That's why I included weights - however you're calculating shipping costs, you should be able to apply it to the above. It also implies your factories are going to be geared to produce more colonies, although at TL9 you can probably reconfigure them fairly readily once the work is done (you may need to replace your initial factory workers with ones trained to produce the goods you actually want). I’ll also mention the reason I opted to have factories instead of just mining facilities - I’d expect the cost of shipping to be too much to justify shipping raw materials, so completed components (which are worth more per unit weight) seemed a better bet. If you want the mining colony to just mine and ship raw materials, you lose the bootstrapping option (thus needing to ship the full 6.15M tons) but reduce the cost of the facility to around $610B (and 5/6 of that is the solar panel arrays powering the factories). Humorously, while production goes down markedly, you can reduce cost to around 1/10th normal if you have the Lacks Automation switch in play.


*EDIT: And now I see you actually intended for there to be only 6000 jobs. Did you mean only 6000 people working at all (implying 40% unemployment, unless you want some of those 10k to be children... but then I probably have too many habitats and open spaces), or only 6000 working in mining (and manufacturing, in my example)?
**EDIT2: Rereading, I also see I somehow thought SM+14 needed 300 workspaces, rather than the 100 it actually needs. That means the habitat management calls for only 300 workers, but I'll still go with 6000 working in mining and manufacturing (which works out to 4800 miners, 1200 factory workers).

[AlexanderHowl]

How much does it cost under your scenario to transport people to Luna? Of, you should also consider that your solar panels only operate for 1/2 the lunar month, unless you put your station at the lunar poles, which have their own issues (an extra 2 mps of delta-v both ways). Unlike solar, fission or fusion can work 24/365 (though I prefer fusion to fission due to the space and worker efficiency).

[Varyon]

Originally Posted by AlexanderHowl

How much does it cost under your scenario to transport people to Luna?

I didn't bother calculating that - whatever methods you end up using for transport (and calculating the price thereof) would work with my suggestion.

Originally Posted by AlexanderHowl

Of, you should also consider that your solar panels only operate for 1/2 the lunar month, unless you put your station at the lunar poles, which have their own issues (an extra 2 mps of delta-v both ways). Unlike solar, fission or fusion can work 24/365 (though I prefer fusion to fission due to the space and worker efficiency).

I failed to consider that. Replacing with fission drops the price by around $200B. Replacing with fusion increases the price by around $200B but reduces the weight by 1.5M tons. Depending on assumptions about lunar resources and/or how your technology works, you may need to ship the entire power-producing apparatus to Luna, rather than being able to bootstrap it.

[AlexanderHowl]

The surface of the moon possesses plenty of thorium, so it is possible to use a thorium fission reactor with available resources. You wouldhave to activate the thorium with a small particle accelerator (easily enough done with resources from a college physics lab). An additional benefit of using thorium is that the radioactive waste is easier to deal with, though that is a minor benefit on the moon.

[johndallman]

Originally Posted by AlexanderHowl

The surface of the moon possesses plenty of thorium, so it is possible to use a thorium fission reactor with available resources. You would have to activate the thorium with a small particle accelerator (easily enough done with resources from a college physics lab).

A college particle accelerator will let you make U-233 from Thorium-232 in microgram quantities. To make it in reactor quantities, there's no way other than a already-running reactor, unless you want to start using fusion bombs.

[AlexanderHowl]

I am not sure if that is necessarily true. I came up with a design around a decade ago as an intellectual exercise that accelerated a lithium plasma at uranium targets to produce a spray of a neutrons to activate molten thorium, and it was nothing beyond what the local university could produce from what the physicists I knew told me. Admittedly, it was an absolutely insane design to use on the Earth, it produced U-236 as a byproduct, but it would be fine for the moon.

[Flyndaran]

Wouldn't that, at worst, just mean you need to bring a single fission reactor to get things started for the thorium breeders?

[AlexanderHowl]

I do think that you are correct.

[Varyon]

Now that I've run the numbers, it looks like a minimum cost of $5.7k/ton, and a maximum of $10k/ton, to get to Luna, depending on if laser rockets are available for reaching orbit. Note I’m assuming fission reactors for the following. In all cases, anytime you ship Habitat modules, you ship their inhabitants with them. All the below use the $5.7k/ton shipping cost.

The no-bootstrap colony, where you send everything to the lunar surface, costs $950B for the colony itself and $35B for shipping. Total cost is $985B. No need to worry about shipping in colonists - they all came with their Habitat modules.

The fast-bootstrap colony, where you ship 4% of the colony and have it build itself, would cost $38B for the colony itself and $1.4B for shipping. Once it’s built, you’ll need to ship in additional colonists, which will increase price. Total cost is $39.4B, plus whatever you pay to ship in your colonists.

The slow-bootstrap colony, where you ship 50% of the colony and have it build itself, would cost $475B for the colony itself and $17.5B for shipping. Once it’s built, you’ll need to ship in additional colonists, which will increase price. Total cost is $492.5B, plus whatever you pay to ship in your colonists.


As for shipping in additional colonists, you have a few options. The cheapest is as cargo - put them in a spacesuit and strap them in. Call it 0.2 tons (and thus $1.14k per person), including luggage. Seeing as they need to stay like that for a several days of travel, it’s not ideal. For a more comfortable experience that’s markedly less likely to involve possible human rights violations, take the HEDM Lunar transit vehicle from the linked post and sacrifice some of its payload space for Passenger Seating or Habitats.