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This might be the most nonsensical proposal I have read in a while. Because why should we build things on the ground and deliver the finished products in orbit

This might be the most nonsensical proposal I have read in a while. Because why should we build things on the ground and deliver the finished products in orbit, when we can push an entire industrial chain into orbit and furnish it with the vast quantities of required inputs, while taking advantage of the vast nothingness that exists there, and the 100000 times more expensive labor. It's like Elon Musk's Mars city, but in vacuum, with zero in situ resource utilization.

techdragon 4y ago
I think you’ve misinterpreted my point, I agreed with the point your making about complex supply chains and components. I specifically said that its only going to make sense for some specific items, and I was specifically thinking the first candidate would be bulk low density support structures. For all the structural aluminium isogrid beams, and perovskite solar panels that are the end products of specialist supply chains with the exact issues your talking about In a large scale on orbit construction project, like a space based solar power station, we could manufacture complex interlocking units on the ground like space station modules on the ISS, and hope all the power routing, and docking, and everything else, will work together when launched… or we can build it the old fashioned way, but with robots or astronauts up in space… bolting, welding, wiring, cabling and routing everything up there from easily made standard parts that meet the requirements. Just like large photovoltaic solar farms are built on earth, with X units of photovoltaic panels, attached to structural support frames suitable for the location they are being installed at (wind loads, thermal range, etc) … and everything cabled together with hundreds of little plastic clips and miles of copper wire in weatherproof plastic conduit. Now some things will obviously be different in space, like hundreds of plastic clips are obviously a space debris risk, so they probably won’t design cabling systems that need that sort of support. But they will need to manage lots of power and data cables which will need some level of protection from the slow but steady degradation by various forms of radiation and plasma from the Sun and deep space, and it turns out a few millimeters of plastic can get you years and years of protection from oxygen plasma which would could eat away at exposed wires and slowly increase the risk of short circuits. Yes it might need to be replaced regularly, but so will other things, and then you don’t need to use crazy specialised oxygen plasma resistant wire insulation… Space is hard, but we build things for way more harsh environmental conditions on the ground all the time in industrial applications. What they don’t need that space currently does, is earth based industry doesn’t usually care about total weight. Starship will revolutionise space not by magic, but by slashing the cost per kilo and allowing us to use more normal engineering procedures and hardware where appropriate. Like panels and wiring and support structural girders. My point was that 3d printing lightweight plastic structural parts where they are needed, will be to space based solar power, what mixing concrete on a construction site is when compared to having everything transported to the site via cement mixers. Sometimes it makes sense for the project to mix on site, other times it won’t. I’m not sure what there is to argue with about this thesis.
- manholio 4y ago
  > My point was that 3d printing lightweight plastic structural parts where they are needed, will be to space based solar power, what mixing concrete on a construction site is when compared to having everything transported to the site via cement mixers. Sometimes it makes sense for the project to mix on site, other times it won’t. I argue that any kind of large scale structure fabrication is fundamentally different than the preparation of raw inputs, like your concrete example. A large orbital 3D printer is a complex industrial machinery that needs servicing, constant supervision and human involvement, it's more akin to the Hubble telescope than to an concrete mixer. The costs to operate it in space are orders of magnitude higher than on the ground even in the most optimistic orbit cost reduction scenario, short of space elevators and the like. Until we have self replicating and selfrepairing orbital robots, any space project will need to contend with the fact that human labor in a spacesuit in orbit is inconceivably more expensive than a guy riding his bike to the factory in sweatpants, breathing the free air our planet seems to have aplenty and drinking the water that falls from the sky from time to time. And this is, I repeat, a fundamental stumbling block no matter how far launch vehicles advance, space will always be insanely hard compared to surface. So you better have a damn good economic case for printing structures in orbit which are 1000x more expensive than the same structures built on earth. The savings from the support structure and the lack of foldable mechanisms necessary to deploy into orbit could be significant, but definitely less than a single order of magnitude.
  - Nomentatus 4y ago
    Costs for both paths will go down steeply over time. But launch costs can only go down so far given the sheer amount of fuel necessary to launch anything into orbit from earth. Remember maintainance robots will come, not just more reliable and cheaper printers that are very lightweight (used at the end of a long flexible arm.) 3D printing aluminum isn't, you know, rocket science.
    - manholio 4y ago
      You don't seem to resonate witn the basic premise of this discussion: the mass of the structure must stil be lifted into orbit in the form of raw materials, printer fillament, etc. We were debating the finer points of wheter the high cost of space fabrication is covered by space optimized design that will never need to experince atmospheric drag, gravity, launch forces, vibrations and volume constraints etc.

techdragon 4y ago

I think you’ve misinterpreted my point, I agreed with the point your making about complex supply chains and components. I specifically said that its only going to make sense for some specific items, and I was specifically thinking the first candidate would be bulk low density support structures. For all the structural aluminium isogrid beams, and perovskite solar panels that are the end products of specialist supply chains with the exact issues your talking about In a large scale on orbit construction project, like a space based solar power station, we could manufacture complex interlocking units on the ground like space station modules on the ISS, and hope all the power routing, and docking, and everything else, will work together when launched… or we can build it the old fashioned way, but with robots or astronauts up in space… bolting, welding, wiring, cabling and routing everything up there from easily made standard parts that meet the requirements. Just like large photovoltaic solar farms are built on earth, with X units of photovoltaic panels, attached to structural support frames suitable for the location they are being installed at (wind loads, thermal range, etc) … and everything cabled together with hundreds of little plastic clips and miles of copper wire in weatherproof plastic conduit. Now some things will obviously be different in space, like hundreds of plastic clips are obviously a space debris risk, so they probably won’t design cabling systems that need that sort of support. But they will need to manage lots of power and data cables which will need some level of protection from the slow but steady degradation by various forms of radiation and plasma from the Sun and deep space, and it turns out a few millimeters of plastic can get you years and years of protection from oxygen plasma which would could eat away at exposed wires and slowly increase the risk of short circuits. Yes it might need to be replaced regularly, but so will other things, and then you don’t need to use crazy specialised oxygen plasma resistant wire insulation… Space is hard, but we build things for way more harsh environmental conditions on the ground all the time in industrial applications. What they don’t need that space currently does, is earth based industry doesn’t usually care about total weight. Starship will revolutionise space not by magic, but by slashing the cost per kilo and allowing us to use more normal engineering procedures and hardware where appropriate. Like panels and wiring and support structural girders. My point was that 3d printing lightweight plastic structural parts where they are needed, will be to space based solar power, what mixing concrete on a construction site is when compared to having everything transported to the site via cement mixers. Sometimes it makes sense for the project to mix on site, other times it won’t. I’m not sure what there is to argue with about this thesis.

manholio 4y ago
> My point was that 3d printing lightweight plastic structural parts where they are needed, will be to space based solar power, what mixing concrete on a construction site is when compared to having everything transported to the site via cement mixers. Sometimes it makes sense for the project to mix on site, other times it won’t. I argue that any kind of large scale structure fabrication is fundamentally different than the preparation of raw inputs, like your concrete example. A large orbital 3D printer is a complex industrial machinery that needs servicing, constant supervision and human involvement, it's more akin to the Hubble telescope than to an concrete mixer. The costs to operate it in space are orders of magnitude higher than on the ground even in the most optimistic orbit cost reduction scenario, short of space elevators and the like. Until we have self replicating and selfrepairing orbital robots, any space project will need to contend with the fact that human labor in a spacesuit in orbit is inconceivably more expensive than a guy riding his bike to the factory in sweatpants, breathing the free air our planet seems to have aplenty and drinking the water that falls from the sky from time to time. And this is, I repeat, a fundamental stumbling block no matter how far launch vehicles advance, space will always be insanely hard compared to surface. So you better have a damn good economic case for printing structures in orbit which are 1000x more expensive than the same structures built on earth. The savings from the support structure and the lack of foldable mechanisms necessary to deploy into orbit could be significant, but definitely less than a single order of magnitude.
- Nomentatus 4y ago
  Costs for both paths will go down steeply over time. But launch costs can only go down so far given the sheer amount of fuel necessary to launch anything into orbit from earth. Remember maintainance robots will come, not just more reliable and cheaper printers that are very lightweight (used at the end of a long flexible arm.) 3D printing aluminum isn't, you know, rocket science.
  - manholio 4y ago
    You don't seem to resonate witn the basic premise of this discussion: the mass of the structure must stil be lifted into orbit in the form of raw materials, printer fillament, etc. We were debating the finer points of wheter the high cost of space fabrication is covered by space optimized design that will never need to experince atmospheric drag, gravity, launch forces, vibrations and volume constraints etc.