This is an article on Stanford Encyclopedia of Philosophy which explains, to some extant, what we understand with Republicanism.
This is a link to John Stuart Mill’s famous and influential essay On Liberty. This work is the base of what we mean with classical liberalism.
This guy explains not only that asteroid mining is feasible, but also how it will work.
This guy explains why space elevators are nonsense. He explains in plain language the technological issues regarding building space elevators. Conclusion: space exploration/travel/colonization will depend on (chemical) rockets.