Yes, there are plenty of things we don’t do here because it’s cheaper and simpler to buy off the shelf. But just because something can’t be 3D printed, does not mean it can’t be fabricated. Local metals can be worked… my dad had his tiny personal Unimat in his basement for making fine parts, which he took from his lab when he retired. That and a drill could probably make hot ends for 3D printing. Solar power could be used to melt metals for rough casting. Perhaps that can be used with local metals to make a bigger machine shop - and so on. Not sure how important some materials are - you can build less efficient electric motors with plain metals and wire, if that’s all you have. On earth, we have far more efficient equipment because the supply chain allows it. The tools and fabrication devices you make with those sorts of local manufacture can probably be used to build fancier, more precise tools as necesary. Again, it’s a bootstrap process.
The vision processing elements on robots probably would benefit greatly from fancier imported chips. But those would be surface mount, and possibly custom designed to minimize the pins so as to make mounting them on locally made (printed) circuit boards simpler. But the air circulation or water pump controllers, or the systems running airlocks or aiming solar panels or controlling the metal processing plant don’t need high-tech chips, a 6502 might even suffice. Presumably you could even generate plastics and such hydrocarbons or other chemicals using raw materials and solar power - we don’t now because better inputs on earth are far cheaper. But a colony will not need the volume or production and will be frugal with what they have.
Yes, the initial start-up will be expensive, and really there is no financial purpose in building a moonbase or Mars base.
At some point you need the facilities for making diamond-tipped and other specialty machine tools… but like the microchips, that’s small enough that it can be considered a “vitamin”, for which it’s acceptable to just get a very large (i.e., a fraction of a ton) supply from Earth, to last for centuries.
But yeah, 3D printers get all the attention, but CNC metal mills are in many ways much more impressive.
Hmmm… do smaller diamonds form from meteor strikes?
I see more of a problem in finding specialized minerals - rare earths, the more rare metals, uranium, etc. Here we scour the whole earth, and still some new mineral finds happen every year. I suppose the major advantage of Mars or the moon is that mostly the geology is not hidden by oceans, or a layer of flora and alluvial deposits (at least, not recently on Mars).
I’ve wondered about mineral veins on Mars and the Moon. On Earth, plate tectonics continually resurfaces the planet, and the weather erodes things.
Many of the precious metals on Earth came from bombardment after it formed. Most of those are now in the mantle or core. But on the Moon and Mars, there is little weathering and no plate tectonics, and anything deposited onto the surface over billions of years is still within a few meters of the surface. And on the moon with zero atmosphere, even micrometeorites make it to the surface and deposit themselves there.
And to @Chronos point earlier, if Starship actually makes the ‘aspirational’ cost estimates per kg, It will actually be profitable to mine precious ketals on the Moon and Mars and ship them home. $70 per kg for shipping is a trivial amount when shipping gold, platinum,mor other valuable elements. Even at $700/kg it would be worth it for gold or platinum. Gold today is at $62,000/kg, platinum about $30,000/kg.
Gold and platinum and orher precious metal mining for export could actually become part of a Lunar or Martian economy.
Eh, I’m not sure there’s enough value in precious minerals to support that. Sure, the first kilogram is worth $62,000, but there’s a fairly small and already mostly-saturated market for gold. Bringing back enough to make a significant dent in the space program’s costs would probably be enough to have a major impact on the price of precious metals.
It can just be one of numerous ways to make money. It may not pay for a space program, but it might pay for some company to prospect for precious metals, adding to the lunar or Martian economy.
In 2009, LCROSS hit the moon and a second satellite did a spectroscopic analysis of the results. They were looking for water in the ejecta plume, and found it in the ratio of about 10-12 gallons per 1,000 lbs of ejected material. But they also found a treasure trove of other volatiles and materials like ammonia, methane, CO and CO2, Hydrogen sulfide, ammonia, gold and silver among many other elements.
If the moon has mineable quantities of nitrogen, it has everything needed for growing crops. Tests have been done on converting the regolith to soil, and that turns out to be pretty easy. The limit was always the massive amount of nitrogen you need to grow substantial crops, but we may have a large source of it in the permanently shadowed craters, and maybe in lava tubes.
The Moon’s surface is 45% oxygen, so we have oxygen, Nitrogen, Argon (useful as a buffer gas for breathing), etc. If we could find smaller lava tube sections and seal them, we might be able to pressurize them and grow conventional crops or hydroponic farms and have huge living spaces for people without the need for suits.
Would you rather live in a 20 x 20 ft dome on Mars, buried under 3 feet of regolith, or live in a space hundreds or thousands of feet in diameter, with a constant temperature and a breathable atmosphere?
The Starship will have a life limit (say, 20 years) and a cycle limit (perhaps 100 uses). Going to Mars and back means it’ll only get 10 cycles instead of the full amount. But just going to LEO and back only takes a few hours, and adding a few days of processing time means it’ll still hit the cycle limit before it needs to be scrapped.
There’s also amortization cost. Even if there was no life limit and you could hit the cycle limit, you still have to pay interest on the ship. It’s much better if it pays for itself in a year instead of several decades.
If you’re really dead-set on lava tubes, they have 'em on Mars, too. Not quite as large, but still hundreds of meters across. They may or may not prove to be useful for habitation, but they aren’t an advantage the Moon has over Mars.
I suppose if you found a vein of pure or nearly pure gold near your Martian colony, it might be worth it to ship to Earth. But at least on Earth, small amounts of gold is extracted from tons of other material, with the use of cyanide.
The problem being, recoveriing gold in any quantity (or anything valuable, diamonds etc.) will destroy its value as a commodity. If the amount of gold available in the world were to suddenly double, it would be disruptive. (I saw something that said the total of all gold mined throughout history would be a cube about a football field long on each side.)
Wired published an article over a decade ago suggesting that we were on the verge of making huge flawless artificial diamonds - apparently there are now artificial diamonds, but if we can make them in decent sizes someone is limiting production. (But that just brings up the whole “why are diamonds valuable?” discussion.)
Mining of some material probably only makes sense if it enables some new valuable capability back here on Earth.
Maybe there turns out to be an easily accessible resource of tritium that enables fusion energy production in a manner that unlocks a step change in energy availability and price.
Or a currently actually rare rare earth, that if available in industrial quantities, allows for spectacular new metal alloys. And so on.
(Or maybe even magnetic monopoles.)
Feeding existing markets for current technologies is not going to pay for mining in space.
We’ve had those for a while. I was at a physics colloquium in grad school (so, some time over a decade ago) where the speaker’s work required the use of large, gem-quality diamonds. She brought one with her to show us. It was literally the size of a golf ball. And no jeweler would be interested in buying it, because the market’s been conditioned by De Beers that that’s “not a real diamond”.
There are also processes by which poor quality natural diamonds can be purified and turned into high quality gemstones:
There are other artificial diamonds made bynthe same heat and pressure processes that natural diamonds are formed put of. There’s pressure to have these diamonds specially marked as ‘manufactured’ to protect DeBeers and other diamond miners, but they are absolutely impossible to distinguish oterwise.