ElPez posted:

One issue of built orbital stations I don't see come up often is that of just keeping up with the gradual decay of the interior and the structure itself. Condensed water, particulates, microorganisms, etc. is going to build up everywhere and corrode stuff, especially in inaccessible places like ducts and the insides of machinery, so it needs to be easy to keep clean. Even so, modules would have to be continuously broken up and replaced when their maintenance stopped being cost-effective. And with a small, closed ecosystem and low organic diversity you're going to be facing the space version of algal blooms.


Simulated gravity, direct sunlight, clean air, downtime, etc: All luxuries. A space habitat is going to look (and presumably smell) something like this most of the time:



In general, I suspect there are big remaining challenges in a lot of relatively unglamorous fields like ecology, biology, industrial processes and modular design. The rocket stuff is mostly working, and it's just a tiny piece of the puzzle anyhow.