This question is a continuation of Unprepared and Without a Homeworld.

The Scenario

In my previous question, I proposed a theoretical near future in which a population of 10s of thousands of people live in space.

The vast majority of these people are machinists, pilots, geologists, chemists, engineers, industrial architects, etc. Manual labor would be mostly automated.

For understanding of how these people are living, the majority of this population exists in mining colonies distributed throughout the asteroid belt. Asteroid colonies would include hundreds of smaller, not-self sufficient bases with crews of 5-50 people, with a few dozen mostly self-sufficient industrial/economic bases with populations typically in the 200-1000 range. The total population in the belt would be about 40,000.

There would also be a larger base on Mars with about 10,000 people which would serve as an industrial center for building and maintaining the majority of the ships, space stations, and durable goods in the belt.

The general overview of the trade economy would sort of look like:

  • Luxury goods, polymers, and advanced technologies would be imported from Earth to Mars.
  • Mars would combine the polymers and advanced technologies with less advanced parts made from local resources to supply the belt with most of their manufactured goods.
  • Mars would also act as a distribution center for the luxury goods from Earth.
  • The larger asteroid bases would contain artificially lit farms that would produce regular shipments of consumer goods to the smaller mining bases.
  • The larger asteroid bases would also contain refineries that process ore that they get from the smaller bases. Most of this ore would then be shipped back to Earth, some might also go back to Mars.

The Problem

Based on a Ideal size for a relativistic generation ship?, it is estimated that it would take 23,000 tons of infrastructure per person to make space survival; so, assume the total mass of colonies is probably about 1.1 billion tons of infrastructure to support human life, plus a few billion tons of infrastructure to support all the cumulative mining, processing, manufacturing, shipping, and storage needs of the population.

I'm hoping for a near future scenario which is not so far in the future that modern governments and technology are still mostly relevant and recognizable, but I'm having trouble reconciling that with the several billion tons of mass required to build such colonies. According to this article, it costs 62 million dollars per launch to send 70 tons to mars. So, 3 billion tons of infrastructure would take ~266 trillion dollars just to launch into deep space barring any cleaver cost cutting solutions.

The one unrealistic technological breakthrough that can be assumed to be discovered within the next few years is cheap cold-fusion. If other un-developed technologies are proposed, please cite a source that gives reason to think it would be plausible to expect within the timeline given.

The Question:

Assuming the collective Governments and Corporations of the world decided today that colonization and mining of the asteroid belt should be treated as a major priority, how could costs be cut to make this doable in the next 25-50 years using no more than 10% of the world's GPD?

  • $\begingroup$ Ignoring the premise of wanting to colonize a region that has only a handful of rocks big enough to land a couple of people on: how will you judge the best answer? We can compare it to gearing up for war or the effort to land on the moon, but you're suggesting something much bigger. We're guessing. How will you judge the best guess? $\endgroup$
    – JBH
    Commented Jan 18, 2019 at 18:15
  • $\begingroup$ Think of it more like a big government sponsored gold rush meets the space race. There is a thing that is only known to exist in the asteroid belt that is valuable enough to make the effort worth the risk. Controlling it would be the future day equivalent to controlling the modern day oil industry. Best answer would be the shortest time-table that could be plausibly achieved without crashing the Earth's economy or unrealistic leaps in technological advancement. $\endgroup$
    – Nosajimiki
    Commented Jan 18, 2019 at 18:44
  • $\begingroup$ But that's my point, how will you judge whether or not any time given is the smallest that won't crash the planetary economy or that didn't require unrealistic leaps of tech. What's an unrealistic leap in tech? Please think this through. Until then, I need to VTC OT:POB. You might want to consider why you're asking the question since almost any time from a decade to a century would be believable. $\endgroup$
    – JBH
    Commented Jan 18, 2019 at 19:00
  • $\begingroup$ I'm with @JBH on this - looks like a VTC: OT:POB to me. $\endgroup$ Commented Jan 18, 2019 at 19:25
  • $\begingroup$ As a rough upper bound, you could probably divide the amount of material you want to send to space by the weight of one of our long-range probes(like Voyager) to get the number of rocket launches needed using today's tech, then multiply by the number of launches we can realistically do in a year. That's a very rough estimate though (and probably not too useful), but anything better would depend more on the specifics of your world than our world. $\endgroup$
    – Giter
    Commented Jan 18, 2019 at 19:39

2 Answers 2


It would be next to impossible to do so within the given timeframe. The two primary bottlenecks would be the availability of heavy boosters to LEO and transfer windows (Earth-Mars windows happen roughly once every two years http://clowder.net/hop/railroad/EMa.htm ). As to transfer windows to the asteroid belt it is a bit more complicated, as they have to be calculated for each individual target. You can ignore the transfer windows, but your journeys will require much more Delta V and will last longer.

If you allow timeframe closer to a century it might just be doable, provided a few developments:

  1. A space elevator is a must. Some promising materials are already being developed so it is not entirely unfeasible. But I believe that it is still roughly 50 years away.

  2. A lunar base would be advantageous to cut down on the cost of materials and fuel extracted from the regolith (as compared to lifting them up from Earth). Regolith contains amongst other elements: oxygen, iron, aluminium and magnesium.


  1. If at all possible we should utilize Von Neuman probes for mining. It would probably be impossible to replicate the control systems in situ, but a single probe could carry enough spares to build several probes from materials mined from asteroids. This option has the potential for the highest reward, as a partially self-replicating probe could be sent within decades, but on the other hand lack of a single type of resource at the target asteroid, could cause the whole mission to fail.

In essence, my plan would be as follows: using conventional boosters colonize the Moon and create shipyards on the surface, or in lunar orbit. Then begin either colonizing the asteroid belt or moving smaller asteroids closer to Earth for mining. Colonization of Mars would be best left till the end, as it doesn't really provide a significant advantage (it is just another gravity well one has to deal with while moving material). However, either a fully automated or small scale manned ISRU installation could be active from the beginning, stockpiling refined materials for the full-scale colonization.


"How could costs be cut to make this doable in the next 25-50 years using no more than 10% of the world's GPD?"

Invent cheap, low-power anti-gravity.

(Example: Traveller RPG)


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