One of my first thoughts, on reading through this idea, is the question of how people got there in the first place, and what became of that? If they're native, how did they survive before inventing glass (or did some catastrophe somehow thin the atmosphere over the course of a few generations?), and if not, how did they lose (or why did they abandon) the spacefaring technology?
atpollard wrote:
We still need a good source of power for an industrial revolution, but burning wood and coal is impossible, so let’s substitute giant solar mirror farms to focus sunlight on an iron boiler to produce steam power.
As the atmospheric pressure falls, the boiling point of water also falls; I don't know what effects that fact might have on steam power on a thin-atmosphere world.
atpollard wrote:
Trains would be nice to travel between cities, so with minimal (super tech) we can concentrate radioactive isotopes to produce a heat generator that has fuel to last years. Now trains only need to take on water to flash boil over a RTG and power a steam engine.
Trains could perhaps be powered by solar-generated steam instead of positing any form of nuclear power: have the train carry lenses to focus the sun on its boiler.
If one went with a world more like Lewis's Malacandra of
Out of the Silent Planet, with thin-air highlands over most of the planet but most of the population living in (if you follow Lewis and his inspirations) narrow thick-air lowlands, one could posit reasonably plentiful trees, and so wouldn't have to come up with replacements for wood and charcoal (except where our world required coal because wood and charcoal didn't burn hot enough) ...