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Orbital construction facilities have a great many advantages over ground based ones: You can use materials from space without having to drag them up the gravity well, you can make vessels that don't have any atmospheric capability, and you can cold weld certain metals. However: They also have downsides.

1: Everything is in microgravity: This makes it hard to keep hold of your work and simply removes the possibility of performing some industrial processes.

2: Everything is in vacuum: At least in a 'traditional' orbital construction rig, the thing being built isn't inside the thing doing the building, and even if it were making a solid shell to build ships in is hard.

3: Everything is either too cold or too hot: Space is cold, but heat doesn't move away from hot things very well, so your materials are too cold while your tools are overheating.

4: Large crews...: ...Are hard to feed and maintain while they work.

5: Any number of other things that I haven't even thought of yet.

How can we resolve these issues, or minimise the amount by which they impede our glorious progress towards Spaaaaaaace! ??

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    $\begingroup$ None of the things you mention are deal breakers, you just have to design the appropriate equipment, and adjust your processes. Some things could be build on the Moon, for example, where they can benefit from having some gravity to work with, and then assembled into the finished product. $\endgroup$ – AndreiROM Jan 21 '16 at 17:19
  • $\begingroup$ @AndreiROM: That's why I included the 'minimise their effect' clause. I know they aren't deal breakers individually, but taken as a whole it starts to look a whole lot nicer to just build things on the ground. Designing the appropriate equipment (or starting to throw ideas around) is the point of the question. $\endgroup$ – Joe Bloggs Jan 21 '16 at 17:22
  • $\begingroup$ what level of tech are you wondering about? Present day tech or will answers with "magic" future tech be ok? $\endgroup$ – fiend Jan 21 '16 at 18:05
  • $\begingroup$ You may need to handwave something like a space elevator. Without the elevator, it is far too expensive to get a single worker out of the gravity well. The rule of thumb was it costs a bar of gold to send a can of soda. Most things aren't worth building if they are that expensive. $\endgroup$ – sdrawkcabdear Jan 21 '16 at 18:12
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Many of the issues in building in microgravity are based on lack of experience and a large enough database for quality control. As well, there are time and distance issues (for example, if you have a defective part on Earth, FedEX can deliver a replacement the next day, while waiting for SpaceX to get a launch ready will take several days at best, but more likely weeks or even months).

For the near and possibly mid future, the best way to overcome these issues is to build modules in a factory on Earth, and then assemble completed modular units in orbit, much like the ISS was assembled. There are other historical analogies, the Type XXI U boats built near the end of WWII were built from modular assemblies sent by rail to the shipyard for final assembly, for example.

Even in the Plausible Mid Future, assembly of modules might be done in pressurized bays on the Moon and then sent into space via mass driver, or an asteroid could be hollowed out and spun for gravity and a pressurized bay for building and checkout will be used. A pressurized bay in microgravity may be used, if you are willing to put up with microgravity issues. Robots might (and indeed probably will) do the bulk of the work, but a pressurized bay allows a human quality control inspector easy access and the ability to get in without the restrictions of a spacesuit.

Based on this, future spacecraft and stations might resemble cylinders of various size attached to a central truss work. With construction bays in hollowed out asteroids, the modules could be of pretty impressive size.

As an alternative, for very large construction, a "balloon" could be inflated and pressurized, and construction done inside. The balloon will become the outer hull of whatever you are building, and all the other stuff you need built inside in the comfort of a pressurized environment. A variation of this idea is on the Neofuel site, which uses a rotating balloon filled with ice to form the structure, and the various structural elements built inside: http://www.neofuel.com/iceship/index.html

So in general, the progression will be to build modules on Earth for on orbit construction, then migrate to the Moon to mine materials and then build modular sections, moving to asteroids to make modules until we finally build large enclosures to define the outline of the spacecraft/structure and build the structures inside.

Grab some tools and get busy.

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Assuming present day technology, you could eliminate the vacuum and large crews problem by having a bunch of remotely controlled robots doing the construction. They would be controlled via a ground station below. You also get the added benefit of eliminating health problems that come with extended microgravity exposure for humans.

If we up the tech level a bit and assume we've perfected nanotechnology, then using nanobots (again, remotely controlled) to do the bulk of the contruction would be great.

Basically if you remove the human component, a lot of issues with building things in orbit go away. Remote controlled robots and industrial processes are the way to go.

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1: Microgravity

Some processes might actually be better in microgravity. Examples currently being researched include crystal growth or mixed density allows.

For everything else rotation is your friend. This need not be large wheels for the whole production facility, individual production line machines could have built in centrifuges for any level of gravitational equivalent force. You could have any level of "gravity" that you wanted tailored to your production requirements.

2: Vacuum

A lot of manufacturing processes require vacuum or inert gas atmospheres to displace the oxygen in our air. This would also potentially get you clean room level cleanliness without an atmosphere to transport dust/debris.

Again where you need an atmosphere you could provide one and it could be tailored to whatever need you require, avoiding oxygen, hydrogen, or other contaminants in metal forming works would make for much higher purities than easily achievable on Earth. Individual machines could have localized atmosphere areas varying from something similar to a TIG welder all the way up to fully enclosed pressure vessels.

3: Temperature issues.

Space can easily provide huge variations in temperature, from an ambient temp of ~2.7 K up to focused solar heating of 1000 of degrees. The main difficulty is moving heat effectively. Most large scale industrial manufacturing facilities already deal with this problem using active cooling systems (HVAC) it would not be much different in space. You would have to provide active cooling to parts with no atmosphere to transfer heat, but again in space this could be engineered to whatever heat level you want.

4: Large crews.

Build with robots. On Earth the direction has been for less and less workers with more automation of manufacturing, in space you have the added incentive that providing for the crew is expensive. Tele-presence general purpose robots could be used to monitor, and identify problems that creep up and should be able to fix most problems.

Overall as factories on Earth become more automated and sophisticated, the drawbacks to placing them in orbit decline, while certain manufacturing conditions can only be achieved in space.

The big drawback not addressed is transport costs. Your factories raw materials and supplies would need to all be supplied from orbit or other low gravity locations as launching anything from Earth to the factory is incredibly expensive ($1000's of dollar per pound) and would quickly eliminate any profit. Items could be deorbited to deliver goods to Earth fairly cheaply.

This would require a large amount of infrastructure to be in place before space manufacturing becomes the norm. Asteroid or lunar mining would need to exists along with all of the supporting refining and manufacturing processes to feed your factory. The possibility exists for the first round of factories to produce very high profit items (super computer chips, metal alloys, or medications).

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  • $\begingroup$ Did you have some interesting sources to backup your answer, or which could be useful to peoples interested in that topic? Good answer. $\endgroup$ – MolbOrg Jul 28 '16 at 5:56

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