OrlandoNative wrote:We *used* to use those for tough and/or high temperature applications (think the SR-71 Blackbird); but now composites are generally used. Most of which don't require "hard to find" elements.
Also, there are *vast* areas on Safehold with few or no people. I sort of doubt that any area that might have the necessary elements or minerals would just happen to be right under some high population center.
Even so; who would really have to create an explanation? If Caleb wants to dig on Silverlode; (or anywhere else in Charis); just who is he required to explain his reasons *to*? Similarly for any other noble? Or wealthy property owner like Howsmyn? The "inner circle" isn't going to require an explanation; and no one outside of it can realistically demand one.
As for priorities; that's a somewhat more reasonable argument. However, the war has now been over for several years; and replenishing raw stock for the manufacturing unit in the cave should; by now; have bubbled a bit closer to the top. Especially considering that they don't really have any idea of what they might need to manufacture prior to or after the "Arkangel's return". There's always a chance that something they might need to manufacture just might require some of those same "rare elements". I doubt there was any raw material originally in that unit that was *uniquely* used in the manufacture of PICAs.
It's not so much explaining their activities to the public as keeping spies of other realms from learning of their activities and wondering what the Charisians are up to. Since they haven't actually proclaimed the Writ to be a lie to the whole world, any hint that the Proscriptions might be getting violated behind a cloak of secrecy could lead to tensions escalating once again.
We don't know what advances in materials science will occur over the next few centuries. However tungsten borides and similar compounds (collectively called supermetals because they behave like pure metals) possess extreme hardness we can't currently match with carbon composites and the like. And who knows what would go into a high temperature superconductor? Elements like osmium or iridium could turn out to be key ingredients.
I would probably set this as a higher priority personally. And if the industrial module itself doesn't contain anything exotic you could run off parts for new industrial modules, the same size or bigger, and assemble them at various sites to start making and stockpiling Federation tech. But they've got a lot on their plate and some years left, so it might make sense from their perspective to put that on the back burner for now.
The only way I can think of to detect an electric power grid from orbit would be radio emissions at the AC frequency or its harmonics. Magnetic fields are far too feeble to register except at pointblank range (i.e. right near the ground). Proper RF shielding for generating plants and power lines - which should probably be buried - ought to conceal them from any orbital sensors. It was mentioned the Gbaba had a way to detect neutrino emissions and this, along with radio communications, was how they zeroed in on hidden colonies. Assuming the Federation managed to copy those detectors nuclear power of any kind is out. You'd have to stick with dirty sources (i.e. coal and oil) or green energy like wind, solar, or geothermal taps such as the ones installed in Nimue's Cave.
A lot of their slipping under the radar may simply have to do with the number of aircraft in operation and the number of people using coms. In other words, not many of either. I wonder what would happen if signs of advanced tech appeared abruptly across much of the planet. Light all the major cities up at once - would the bombardment system strike everywhere, or stand down rather than finish the Gbaba's work for them?