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Old 08-08-2019, 04:58 PM
k9bfriender is offline
Join Date: Jul 2013
Posts: 11,339
Originally Posted by Sam Stone View Post
Space colonies by definition have no resources of their own. All they would ever have to sell is whatever people could make there. And since they are going to be under Earthlike gravity, it's hard to think of anything that could be made there that would be worth the cost of shipping the materials to make it to the colony, then shipping the finished goods elsewhere. O'Neill originally thought that the value would be in the real estate, since Malthusian thinking was all the rage at the time. But the Earth has plenty of living space, and will continue to do so. So the colonies have to provide something of value to get the money needed to build and maintain them.
The only resources they have are all of the metals and organics and volatiles that they are sitting on. That's not nothing.

Not all spinning cans are O'Neill cylinders. The only parts that would be under Earth Like gravity would be the areas where people live. Manufacturing can either take place in the middle, or even on a completely separate facility that is co-located with it. You are generally going to want to build these on or in asteroids for protection from radiation and space junk, (and for them being close to mine) so the way I see it playing out is that you have the habitat in a spinning cylinder that is buried under the surface, and most of the manufacturing, especially what benefits form zero g, on or around the surface.

We ship that stuff in extremely energy efficient ways. We ship heavy stuff on the ground and water, where the only energy price we have to pay is the friction of moving it horizontally. That's a far cry from moving billions of kg of mass around in space, especially given the limits of the rocket equation - even with nuclear rockets.
The rocket equation is a real pain for getting off the Earth, or the moon for that matter. The rocket equation does not have the same effect when you are not escaping a gravity well. Moving materials from one asteroid mine/colony to another actually requires very little in the way of delta-V. If it is just materials, and nothing perishable like people, and it doesn't matter how long it takes, it can be done with a few mere meters per second.

Last edited by k9bfriender; 08-08-2019 at 04:59 PM.