My understanding is that there is lots of very fine dust near the surface of the moon. It's continually being bombarded with micrometeorites that kick up the dust.
So perhaps a moderately cleanish room.
There was a scene in https://en.wikipedia.org/wiki/For_All_Mankind_(TV_series) S02E01 where a solar storm surprised some astronauts on the surface, where they couldn't make it into shelter in time. One got toasted, another barely made it into a cave, and watched from there.
It looked like invisible drops of torrential rain, splashing down hard, and stirring the dust up, like in slow-motion capture of a drop of water, impacting, and stirring things up.
I don't know how realistic that is, but I liked it as a conceptual visualization, at least.
Edit: Think of something like a https://en.wikipedia.org/wiki/Cloud_chamber at large scale. Where the medium is stirred up dust.
Edit: A there it is: https://www.youtube.com/watch?v=YzlP403rUGA
That's a process that involves drawing ions through solution towards a cathode and anode. A direct beam won't do.
A solar furnace would suffice for the first half of the smelting process if you have access to ore which is not pure alumina, as well as melting the cryolite flux. Actually separating out the aluminum from alumina requires PV panels, high temperature rods and some means of synthesizing the cryolite or similar solvent / flux.
OK, thanks for the info. Can you go into more depth about this specific part, or is this a thing where I need to do the whole degree to understand the answer?
As I understand it, the currently accepted theory about how the moon formed is the giant-impact hypothesis, which is that a very large object hit the proto-Earth and the moon is the material that was "splashed" off when this happened. As such it seems at least plausible that the moon would have a similar set of elements available for semiconductor production as Earth does.
All of this is inputs that led to the impact model of moon formation.
3D printers aren't Star Trek replicators. You can't take a manufacturing flowchart, add a "3D printer" node in the middle, and then consider your manufacturing problem solved. Even if you had a magic 3D printed that could print pipes and fasteners and ducting, it would still need to be assembled and the facility processed to get it clean enough to build semiconductors. Then you'd need smelters/factories processing raw materials to get the necessary feedstocks. Then you'd need reprocessing facilities that could recycle wastewater to be reused and catalyze waste chemicals to reuse.
Similarly, semiconductors don't only mean the really good ones we use now (though once you have the capacity to make an appropriate factory, obviously you should do that), there are also relatively easy but also mediocre options like copper oxide.
Looking at the tech timeline, the first (semiconductor) PV predates quantum physics: https://en.wikipedia.org/wiki/Timeline_of_solar_cells
Edit:
If it takes merely literal tons of pre-made equipment from Earth to bootstrap, that's easy. Musk's (for all I know paper napkin) stated intent of a million colonists is ~100,000 tons just of human biomass.
Where are you going to get that, or any other raw material? Robot miners? We don't have those on Earth yet.
How do you purify it? All our chemical processes require huge quantities of free air, and of very cheap water, neither of which you have on Mars.
Where do you get the power for all of this? Solar panels don't behave well during sandstorms, the sun isn't very bright there, and how many solar panels can we really fly to Mars?
It's a pipe dream. We will destroy our ecosystem long before we manufacture even one thing on Mars.
Bootstrap with whatever the initial mission payload is. It's not like anyone is proposing magically teleporting there without stuff, IIRC even Musk's optimistic idea is still several no-humans flights for each passenger flight.
> Robot miners? We don't have those on Earth yet.
Sure we do. TBMs. Not all of which are manned. A few of the missions on Mars right now are taking rock samples with drills.
(Honestly, I'm mainly thinking of the moon, but Mars has moons too. No idea if any of Mars, Demios, or Phobos have significant easy access to aluminium oxides).
> Where do you get the power for all of this? Solar panels don't behave well during sandstorms, the sun isn't very bright there, and how many solar panels can we really fly to Mars?
Sure, PV. They do suffer as you say, but that's not a critical failure when bootstrapping a colony or whatever, especially when you're in the "robotic labor only" phase that (a) is a prerequisite and (b) Optimus Prime or whatever random pop culture reference Musk named that middling demo after. While I don't have any reason to actually trust Musk's "million people" number as anything more than a nice round number, at that kind of scale you necessarily have a lot of PV. Like, "tens of square km" is the minimum baseline. How much is made locally vs sent by Starship depends what can be made locally vs. what can't.
Plus, a Mars colony is one of the few situations where orbital solar via microwave isn't obviously worse than "a big wire to the other side of the planet".
As Starship has ~100T payload, and this PV is 120 W from 5.2g, given 50% reduction in sunlight relative to Earth, even if all the semiconductors have to be shipped from Earth, it's only a few flights out of what you need just to get the people, never mind the other bootstrap equipment you also want: https://spectrum.ieee.org/ultrathin-solar-cells-for-lightwei...
To ignore the massive difference in scope and scale between a space probe with a tiny rock drill and a tunnel boring machine, TBMs require literal tons of lubricants/coolant to operate. Even if you had a 100% electric TBM none of its parts are going to move without lubrication. Even "unmanned" TBMs aren't fully autonomous, they have a small army of squishy people in hard hats adjusting fasteners, checking feed lines, repairing damage, and generally maintaining the machine.
TBMs also going to be orders of magnitude more difficult to build for use on the Moon or Mars. They're incredibly dry environments, dryer than most places on the surface of the Earth. The dust is electrostatically charged and literally creeps along surfaces into seams and seals. The dust is also incredibly abrasive. Machinery does not like dust, machinery will hate Lunar and Martian dust.
In actual operation machinery does not look showroom pristine. It gets dirty and needs to be bathed in lubricants and coolants. Dust, dirt, and shavings get everywhere except in the cleanest of cleanroom environments and those take tons of effort to maintain.
Everything around you was manufactured with a very long tail of infrastructure. You can't just build a PV factory on Mars. You need to first build the infrastructure to build infrastructure before you can lay the first 3D printed brick for a factory. Even if you've got that infrastructure and factory you need a whole supply chain of refined materials to feed the factory to get solar panels.
It's not a handful of unmanned Starship missions, it's a hundred missions with no failures landing billions of dollars of basic infrastructure just to start building more infrastructure. The whole endeavor also needs to use technology like autonomous robotic mining rigs and autonomous mining rig support robots that don't even exist on Earth. I honestly don't understand trivializing the amount of infrastructure and complexity required to manufacturer things here on Earth let alone anywhere else in the solar system.
While I disagree with the specific claim here (bricks are easy mode, sand sintered with a fresnel lens brought from Earth), for the general point you're otherwise making:
Yes, and?
Depending on which bit you're pointing at, "a few" was just for the PV for everyone, or just per manned flight. For the "million colonists" (again, no idea if that's a well thought out number) that's thousands to tens of thousands of manned flights, and 3000 to 50000 unmanned flights each with about 100 tons of payload depending on which random early stage wild guess you use to calculate from.
5 million tons of stuff from Earth may or may not be enough to bootstrap, I wouldn't know. (Does anyone?)
But your specific criticisms… don't feel like they're aware of the scale Musk is aiming for.
On a separate point:
I have read of both liquid CO2 and graphite (which can obviously be made from that) being used as lubricants, but I'm emphatically not suggesting they're drop-in replacements. Obviously one would have to design mining equipment specially to use them, likewise for thermal issues.
Given who owns The Boring Company, this is probably already being researched.
While I would be actively surprised if the Moon, for example, had every element necessary for semiconductors, one of the things I absolutely do expect to be possible on its surface is 3D printing an extremely clean clean-room.
Furnaces? Well, I think it would take a polishing step after printing, but if you have aluminium you can do a rough parabola out of it and focus sunlight on a patch of regolith. Can you turn that molten alumina into aluminium and oxygen only by carbon rods and electricity? Or would electrolysis still work if you used a high-current election beam?
(I genuinely don't know, I didn't do material science).
Don't get me wrong, even if this is ultimately all fine without petrochemicals, I expect there is a lot of postgraduate research between now and any significant space manufacturing.