To build a space elevator, you'll need a very light car and a very strong string.
- By Michael Milstein
- Air & Space magazine, March 2006
(Page 2 of 6)
In fact, NASA backed the contest only to encourage precursor space technology. “We have no plans to build a space elevator,” says Brant Sponberg, manager of NASA’s Centennial Challenges program, which offers cash prizes to fuel innovation in the same vein as the X Prize. The idea is to attract interest in space projects from inventors beyond the usual circle of big contractors that routinely seek NASA funding. “But when you take a space elevator apart into all of its pieces, there are a lot of things we’re interested in,” Sponberg adds. “The basic physics are practical, but the material—not yet. That makes it a hard sell for the agency right now.”
But belief is growing that a space elevator may be in our future. A NASA report completed in 2000 predicted a space elevator would become practical in the second half of this century. Optimists say a functioning system is perhaps no more than a few decades away, if someone savvy in the private sector decides to attempt one.
A couple of companies, backed by venture capital, are already investing in the basics and have scoped out the climber robots in California for ideas. Believers say that as crazy as the space elevator sounds, it’s even crazier to not pursue what could be the cheapest and most reliable route into space.
“We need to sort of open up and use our imagination and creativity,” says Robert Cassanova, director of the NASA Institute for Advanced Concepts in Atlanta, which has paid for some initial studies on the idea. “We need to start with a new sheet of paper and come up with some new ideas. That’s sort of the story of the space elevator. It’s one of these really big ideas. Finally people are starting to take a serious look at it.”
Although the gadgets that showed up in California are as far from the real thing as a magnifying glass is from the Hubble Space Telescope, here’s how the finished concept would work: A floating platform of some kind, perhaps a big ship, would station itself somewhere along the equator. From there a ribbon made of a material stronger than diamonds would stretch about 62,000 miles into space.
The end of the cable would carry a counterweight of some kind, maybe rockets or other left over equipment from construction. The fulcrum of the elevator cable mass would have to be positioned at 23,000 miles— at geosynchronous orbit, where satellites constantly tower over the same point on the planet. But for its center of gravity to be positioned at geosynchronous orbit, the far end of the cable must extend way beyond that point. Like a teeter-totter that sticks out to either side of the balancing point, the cable must extend 62,000 miles, according to the most prominent approach being considered.
Earth’s rotation would whirl the enormous wobbly tower, like a tennis ball on the end of a string. The momentum of the spin would keep the cable taut, and roomy elevator cars would shuttle people and cargo between stations along the line.
The elevator cars would be powered by a laser on the ground—much like the searchlight in the California parking lot—beaming energy to collector panels on each car.