So you got your elevator crawling up the kevlar ribbon, and like the elevator in the building, it is not only forcing itself and its passengers "up", but also "sideways". To reach the classic geosynchronous orbital altitude, you not only have to pick up a lot of altitude, but also several kilometers per second of lateral velocity. ...Yes, but there are ways to deal with that problem. I'm not a rocket scientist, but I play one on TV, and my buddy Robert Cassanova (sounds like a soap opera name, doesn't it?) assures me that the physics is a-ok.
The lateral force on the lower end of the ribbon is a design problem for those who design the anchorage, but it's not really too bad. They can deal with it. The anchorage will be designed to transmit that force into the earth itself, where it can be ignored.
Unfortunately, the lateral force this applies to the counterweight is a pernicious problem which is not so easily solved. Remember our weight hanging from a string? Try pushing slightly on the string. The weight starts swinging, right? That's what's going to happen here.
"Technically it's feasible," said Robert Cassanova, director of the NASA Institute for Advanced Concepts. "There's nothing wrong with the physics."In fact, the biggest problem is most peoples' minds isn't balancing the counter-weight, it's building the cable, as SDB mentions near the end of his post.
Which is all well and good, except that I've given it a lot of thought, and I can't see how you could even get one ribbon connected. I can't figure out any way you can actually build this system.I look forward to reading his analysis, but I've seen plans that sound plausible to me. He may shred these ideas tomorrow, but I may as well tell you what I've seen so far.
You can build an anchorage. You can put the counterweight into space. How do you connect the ribbon between them?
In the next article I'll explain why that's a tough problem.
Getting the first space elevator off the ground, factually, would use two space shuttle flights. Twenty tons of cable and reel would be kicked up to geosynchronous altitude by an upper stage motor. The cable is then snaked to Earth and attached to an ocean-based anchor station, situated within the equatorial Pacific. That platform would be similar to the structure used for the Sea Launch expendable rocket program.A lot of great (kooky?) minds have worked on this concept, and so I'm hopeful that SDB's skepticism is misplaced. Wikipedia has more.
Once secure, a platform-based free-electron laser system is used to beam energy to photocell-laden "climbers". These are automated devices that ride the initial ribbon skyward. Each climber adds more and more ribbon to the first, thereby increasing the cable's overall strength. Some two-and-a-half years later, and using nearly 300 climbers, a first space elevator capable of supporting over 20-tons (20,000-kilograms) is ready for service.
"If budget estimates are correct, we could do it for under $10 billion. The first cable could launch multi-ton payloads every 3 days. Cargo hoisted by laser-powered climbers, be it fragile payloads such as radio dishes, complex planetary probes, solar power satellites, or human-carrying modules could be dropped off in geosynchronous orbit in a week's travel time," Edwards said.
Using a laser beam to boost the climbers into space is doable, said Harold Bennett, president of Bennett Optical Research, Inc. of Ridgecrest, California. "If you do it right, you can take out 96 percent of the effect of the atmosphere on the laser beam through adaptive optics," he said. The strength of the pulsed laser beam is less than the intensity of the Sun, so birds, airplanes, or human eyes wouldn't be affected, he said.