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Agreed, though I suspect there are some processes where a little artificial G would help, but perhaps I'm just too used to thinking in terms of having to contend with weight. I'm thinking of the inspection tools that measure particles, or topography (flatness, thickness, etc). You set a wafer on something, and it's weight holds it on a stable and known surface to be scanned. Vacuum is quite a clean environment to process material though. Easy to keep hot things hot, too. The crucible melt wouldn't require noble gasses to displace oxygen, and the crucible itself wouldn't need to be designed to absorb oxygen and therefore have a very limited duty cycle before being discarded. I could probably think of avantages for nearly every step of the process where a vacuum, and perhaps weightlessness might be advantageous.
Reaching orbital velocity from the moon only requires about 2,200 MPH acceleration. Not too difficult, especially when there's no atmosphere to contend with. You can linearly accelerate a cube of materials to orbital velocity without much trouble or expense.
To really build things economically at scale, we either need to largely eliminate chemical rockets as the primary means of getting material off the earth, or mine materials in space. The energy expenditure of mining and redirecting the material to where you want it has to be less than the energy potential extracted in the process. If we're still burning hydrogen and oxygen for thrust, then the mining effort has to extract more than what's needed to move those materials to where we want them, as an example.
Ion engines seem to be the most feasible technology at the moment, but they aren't very powerful, and they wear out.
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