Rockets are getting us nowhere fast. Since the dawn of the space age, the way we get into space hasn't changed: we spend tens or hundreds of millions of dollars on a rocket whose fundamental operating principle is a controlled chemical explosion. We need something better, and that something is a space elevator--a superstrong, lightweight cable stretching 100 000 kilometers from Earth's surface to a counterweight in space. Roomy elevator cars powered by electricity would speed along the cable. For a fraction of the cost, risk, and complexity of today's rocket boosters, people and cargo would be whisked into space in relative comfort and safety.
It sounds like a crazy idea, and indeed the space elevator has been the stuff of science fiction for decades. But if we want to set the stage for the large-scale and sustained exploration and colonization of the planets and begin to exploit solar power in a way that could significantly brighten the world's dimming energy outlook, the space elevator is the only technology that can deliver.
It all boils down to dollars and cents, of course. It now costs about US $20 000 per kilogram to put objects into orbit. Contrast that rate with the results of a study I recently performed for NASA, which concluded that a single space elevator could reduce the cost of orbiting payloads to a remarkably low $200 a kilogram and that multiple elevators could ultimately push costs down below $10 a kilogram. With space elevators we could eventually make putting people and cargo into space as cheap, kilogram for kilogram, as airlifting them across the Pacific.
The implications of such a dramatic reduction in the cost of getting to Earth orbit are startling. It's a good bet that new industries would blossom as the resources of the solar system became accessible as never before. Take solar power: the idea of building giant collectors in orbit to soak up some of the sun's vast power and beam it back to Earth via microwaves has been around for decades. But the huge size of the collectors has made the idea economically unfeasible with launch technologies based on chemical rockets. With a space elevator's much cheaper launch costs, however, the economics of space-based solar power start looking good.
A host of other long-standing space dreams would also become affordable, from asteroid mining to tourism. Some of these would depend on other space-transportation technologies for hauling people and cargo past the elevator's last stop in high-Earth orbit. But physics dictates that the bulk of the cost is dominated by the price of getting into orbit in the first place. For example, 95 percent of the mass of each mighty Saturn V moon rocket was used up just getting into low-Earth orbit. As science-fiction author Robert A. Heinlein reportedly said: "Once you get to Earth orbit, you're halfway to anywhere in the solar system." With the huge cost penalty of traveling between Earth and orbit drastically reduced, it would actually be possible to quarry mineral-rich asteroids and return the materials to Earth for less than what it now costs, in some cases, to rip metal ores out of Earth's crust and then refine them. Tourism, too, could finally arrive on the high frontier: a zero-gravity vacation in geostationary orbit, with the globe spread out in a ceaselessly changing panoply below, could finally become something that an average person could experience. And for the more adventurous, the moon and Mars could become the next frontier.
So why can't we do all this with rockets? And why is the space elevator so cheap?
The answer is that chemical rockets are inherently too inefficient: only a tiny percentage of the mass at liftoff is valuable payload. Most of the rest is fuel and engines that are either thrown away or recycled at enormous expense. Nuclear and electric rockets promise huge improvements in efficiency and will be vital to the future of solar system exploration, but they are impractical as a means of getting off Earth: they either don't produce enough thrust to overcome gravity or pose a potentially serious radiation hazard.
On the other hand, space elevators could haul tons of material into space all day, every day. And the core of the space elevator--the cable--could be constructed from cheap, plentiful materials that would last for decades.
A space elevator would be amazingly expensive or absurdly cheap--depending on how you look at it. It would cost about $6 billion in today's dollars just to complete the structure itself, according to my study. Costs associated with legal, regulatory, and political aspects could easily add another $4 billion, but these expenses are much harder to estimate.