Are Space Settlements Realistic?

I recently finished watching season 4 of For All Mankind, a rather good science fiction series on Apple TV+. The premise of the show is that in 1969, the Soviet Union beat the United States to a lunar landing, touching off a decades long space race that eventually resulted in settlements in Earth orbit, on the moon, and eventually Mars. All this in about forty years. 

It's a wonderful dream but not very realistic, at least not in that timeframe. Which raises the question: are space settlements possible at all? 

That question is addressed in a new book, A City On Mars, by biologist Kelly Weinersmith and cartoonist Zach Weinersmith. Cory Doctorow reviewed it recently in his Plurastic blog and comes down on the "not realistic" side of the question. 

The Weinersmiths make the (convincing) case that every aspect of space settlement is vastly beyond our current or reasonably foreseeable technical capability. What's more, every argument in favor of pursuing space settlement is errant nonsense. And finally: all the energy we are putting into space settlement actually holds back real space science, which offers numerous benefits to our species and planet (and is just darned cool). 

My own take on it is that there's no way that we will have self-sustaining settlements in space, on the moon or on Mars, much before the end of this century. But I think we still need to start on a small scale, in Earth orbit and on the moon, to develop the ability to live in a self-sustaining environment that eventually can be scaled up to something larger. 

One of the things that will keep large scale space colonization from happening is the detrimental effects on the atmosphere of rocket launches. It's not a major problem right now, but lifting hundreds of thousands or millions of tons into orbit using chemical rockets, even ones using relatively "clean" fuels is going to affect the atmosphere and climate. The only way around this is probably a space elevator, but that needs materials that we don't yet have. 

It may be that humans can't survive away from the Earth (see Kim Stanley Robinsn's novel, Aurora, cited in Doctorow's post). The only way we'll find out is to try and I think we should.