For those who don't track Slashdot, a very interesting review of a book carefully studying the feasibility of a Space Elevator was posted.
For those who don't know what a space elevator is, here's the basics: A satellite is put in geosynchronous orbit around the earth, which is where the satellite always stays above the same point on Earth. A tether from the satellite is extended down to the surface of the Earth, and another is extended away from the Earth a roughly equal distance.
Having done this, you can simply ride up the tether to get into orbit. If you ride up to Low Earth Orbit, it's still an easier burn to stay there then to get there from scratch. It actually becomes easier to loft satellites higher then lower. At geosync, the payoff is even, so you get the satellite into geosynchronous orbit for just the cost of the energy to lift it there. Best of all, you can fling things off the other end of the tether which give them either escape velocity from the Earth/Luna system, or something very close to it.
The "pie-in-the-sky" aspect of this project so far has simply been building a material that can withstand the stresses of being 22,241 miles in each direction. Things get exponentially worse as the strength of the material decreases; I saw some articles from the early nineties, based on real materials, that have the base of a space elevator being several miles in diameter, which isn't really feasible.
However, while few people were looking, this magical material is becoming available in the form of carbon nanotubes. While it is still not possible to build the space elevator on current technology, it is no longer pie-in-the-sky; instead, we only need a factor of 2 advancement in strength on existing materials, and the ability to mass-produce these things. That's still a tall order, but it is now merely an engineering challenge, not insanely difficult.
The hardest part about the Space Elevator is that you must take your common sense off the hook for a bit. I know building a 44,482 mile structure (give or take a bit) sounds impossible, but smart people have been running the math and it can work. Remember the things that we now take for common which were also impossible quite recently, like large majestic bridges and skyscrapers. When the numbers get this large, the intuition must take a back seat to hard math.
In my Slashdot posting I ethused about the economic benefits and the potential problems if Somebody Else (probably China) gets there first, but for my weblog I'd like to take a more philosophical bent, if I may.
Do you remember all those dreams we had in the 1950's? Colonies on the moon, real spaceships (not the tin cans that we fly now), real space tourism? My generation has given up on these dreams. With typical cynicism, we've "come to grips" with the fact that space is impossibly distant and we're not getting there for a long time, until the rockets improve. However, the fact is, after 50+ years of effort, if rockets were going to get us into space, they would have by now. They are too inefficient, expressed in terms of tens of thousands of dollars per pound to lift a satellite into orbit, and too dangerous. Even without actual disasters like Columbia and Challenger, the statistics do not favor safe rocket operation as an operation on the scale of the commercial airline industry.
But with a space elevator, which may be within reach within twenty years for 50 billion dollars (padding the estimates in the book by a healthy margin), we get all those dreams back. With the ability to lift wieght for dollars per pound, we can build real spaceships that can actually hold lots of people and equipment. We can land colonies on the moon. A space elevator built on the moon would be even easier to build (less gravity, no atmosphere) and would make Earth-Moon commerce actually possible for a reasonable price. Mining the moon (which requires a colony to do the mining) becomes possible.
And best of all, it would give us back the Frontier. Once again, we could look outward, and by having hope, many of our problems Earth would at least become solvable in a way they aren't right now because there's no real hope that without a true space program that the entire world can attain even current levels of US prosperity without destroying the planet first. With space resources, this dream is no longer actually materially impossible. It still wouldn't drop in our laps, of course, but at least it would be possible.
We should build the elevator, or at least try, in the final analysis not merely because it will line our pockets with dollars. It is the only really feasible hope we have for restoring hope and the dream of real space exploration in the future.
It's too late for my generation; by the time this is done I'll be at least forty. But we should build this for the next one.