The space shuttle's retirement has prompted me to think a bit harder about the future of the American space program. I always took the space shuttle, and the giant rockets that propelled it, for granted, assuming they were the best and only method of launching things into space. It turns out, however, that somebody thought of making a space elevator way back in the 19th century, and we've had the technology to create one in a lower-gravity environment like the moon or Mars since the 70s.
So what would a space elevator be, theoretically? It's a fairly simple concept, actually -- it would be a giant cable, one end tethered to the ground (or possibly to a mobile platform in the ocean) at the equator, the other end towed past geostationary orbit and attached to a big artificial counterweight in space. I'm notoriously bad at grasping concepts that involve math or physics, but the idea seems designed to place the system's center of mass exactly at geostationary orbit over the equatorial spot where the base of the cable is anchored, thus keeping the whole thing more or less upright (with maybe one degree of bend at certain spots along the cable). Then a cable car of sorts -- or multiple cars -- could climb and descend the "beanstalk," as some call it, at will. The cost and energy savings of transporting materials to space in this manner is potentially huge; currently, it costs around $11,000 to blast a pound of payload into space. With a space elevator, it'd be more like $100 -- just slightly more expensive than overnight FedEx, in other words.
Of course, there are challenges, primary among them developing a cable from material that's both extremely light and extremely strong. Carbon nanotube technology seems to be promising, but despite a number of X-prize-type contests over the past five years or so, we haven't quite clinched it yet. Japan seems especially excited about the prospect of a space elevator -- in fact, an American-penned book called "Leaving the Planet by Space Elevator" was a best-seller there in 2008. From Wikipedia:
This has led to a Japanese announcement of intent to build a Space Elevator at a projected price tag of £5 billion. In a report by Leo Lewis, Tokyo correspondent of The Times newspaper in England, plans by Shuichi Ono, chairman of the Japan Space Elevator Association, are unveiled. Lewis says: "Japan is increasingly confident that its sprawling academic and industrial base can solve those [construction] issues, and has even put the astonishingly low price tag of a trillion yen (£5 billion/ $8 billion) on building the elevator. Japan is renowned as a global leader in the precision engineering and high-quality material production without which the idea could never be possible."
That was a few years ago, though, and Japan surely has other things on its collective mind right now. All things considered, however, this really does seem like a great -- and much more efficient -- way to get ourselves and our stuff into space. I wouldn't be surprised at all if space elevators became a reality in my lifetime.