Yeah, heavy REMs are still expensive but there is really no reason to believe that they'll stay that way. New sites will be found, new extraction techniques will be tried and new processes developed and then the problem will go away. Sure, it could happen in space but it's so much easier to do here on earth that it might never be worth it to go to space for it.
I'm not an emissions system engineer so I can't evaluate the truth of the statement. If it is true, and supply existed: it would create demand, potentially it could even drive up price as potential users quit using less desirable alternatives.
That's a bit of an overstatement. We have a 3d printer on the ISS and me make great strides in producing fiber optics in space that are superior to what we can do on earth at similar price points [1].
1: https://www.nasa.gov/mission_pages/station/research/experime...
Once you have capabilities to build in space, going down gravity wells makes zero sense.
Want to build a factory or physics lab in space. You just mine things there and build them there. After a while you are looking at permanent colonies and then it's useful there.
No, it's not. I'm pretty sure it's silicon. Iron is relatively rare (but not as rare as platinum or gold of course).
Iron is the most abundant element in the Earth, but not on it. The core is full of iron. But that doesn't help us at all, because we can't get to that. We can only access materials in the crust, and there isn't much iron there.
If you include the biosphere, it's carbon. If you include the oceans, it's hydrogen (the hydrogen atoms in water).
Even if you just include inorganic materials in the crust, I believe oxygen is more abundant than silicon (oxygen is part of silicate rocks).
https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elem...
Oxygen is #1, silicon is #2, aluminum is #3, and iron is #4 (though far less than O or Si). Carbon doesn't even rank in the top 9.
It says "in the Earth's crust". That indicates to me that the biosphere and the oceans are not being counted. Also, it's giving abundances by mass, which is not the only way to do it (I was actually thinking of abundance by atom count).
Later in the same Wikipedia article, the top eleven abundances by mass for the ocean are given: oxygen and hydrogen are the first two, carbon is #10, and silicon doesn't even make the list.
No figures are given in that article for the biosphere; my statement of carbon being the most abundant for that is based on the fact that it forms the "backbone" of all of the main types of molecules in living organisms: proteins, carbohydrates, lipids, and nucleic acids.
As for the "crust", the definition of the Earth's crust I'm pretty sure includes the oceans, the seafloor, and everything down to the mantle, so the biosphere and oceans should be counted there. Hydrogen doesn't rank highly because it has little mass compared to other elements. Atom count seems like a pretty pointless metric; we're talking about resources available for mining, in which case mass is what counts.
Of course silicon doesn't make the list for oceans because it's mostly water, and a lot of dissolved CO2. Count the seafloor and you'll find lots of silicon (and probably some iron, aluminum, titanium, etc.).
If the crust included the oceans, there wouldn't be different figures for the oceans in the same article.
You make a valid point about the seafloor being part of the crust; but I didn't intend to include the seafloor in "oceans".
> Atom count seems like a pretty pointless metric; we're talking about resources available for mining, in which case mass is what counts.
That depends on what we're mining the resource for. For example, if we're mining for metals to use in catalytic converters for vehicles, atom count is the relevant metric, since the catalytic effectiveness depends on the number of atoms, not on the total mass.
No, it isn't; each hemoglobin molecule has just four iron atoms in it (IIRC--each heme structure has one, and I think there are four heme structures in one hemoglobin molecule). Most of each such molecule, by either mass or atom count, is carbon. And each red blood cell is more than just hemoglobin molecules.