As a longtime sf fan, one of the toughest realizations I ever came to is that Space settlements will never happen for economic reasons.
In part, the costs of getting to space are too high. Charles Stross has discussed the costs at great length here. To get one person to the Moon, bringing along the life support he needs for the trip, using advanced versions of the rocket technology we have today, would cost about US$400,000 as an optimistic estimate.
That’s far too expensive for anything except government boondoggles or multimillionaire’s larks, i.e., the current state of space travel.
Things get worse as go further in the solar system, even keeping in mind Heinlein’s comment that “Earth orbit is halfway to anywhere.” The cost of travel to Mars or any other place in the solar system would be even higher than $400,000, for at least two reasons: (1) you have to carry the fuel for the return trip, and (2) you have to carry more life support infrastructure for the years of round-trip travel time forced on you by Hohmann transfer orbits.
Interstellar travel? Alpha Centauri is about 250,000 times further away than Mars. The energy cost to get a solitary explorer there in less than one lifetime (at 0.1 c, 40 years in transit) is comparable to the yield of all nuclear weapons ever built, or the energy consumption of the entire world for a couple of weeks. Generation ships are even worse: the energy savings from their slower speed (call it 0.01c, 400 years in transit) is offset by the mass of hundreds of people and the infrastructure needed to keep them alive and safe for four centuries. And we haven’t even touched on the individual and social psychology issues these avenues would bring up. How well would you do living in your car for four decades?
So nevermind settling the solar system; the idea of normal people going into space is so expensive, it’s a non-starter.
About now, a reader might protest, “But what about nanotechnology? Advanced materials and cheap energy production will lower all those costs dramatically.”
I read Stan Schmidt’s mid-’80s Analog editorials on nanotechnology, and K. Eric Drexler’s Engines of Creation. Although I think Drexler is intoxicated with his ideas, I completely agree that some of the fruits of nanotechnology–the super-strong, super-light materials and cheap energy referred to above–are entirely possible, and are in fact likely to appear somewhere on Earth in the coming decades. Yes, those advances will make space elevators and fusion-powered torchships possible. Yes, nanotechnology would greatly lower the costs of space travel and space settlements.
But. Nanotechnology would also greatly lower the benefits of space settlement, leaving the prospect as uneconomical as it is today. More on that point in my next post.