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The Space Elevator Primer

A quick answer book for the Space Elevator, largely independent of the Elevator:2010 project.

Quick Facts
  • The Space Elevator is a thin ribbon, with a cross-section area roughly half that of a pencil, extending from a ship-borne anchor to a counterweight well beyond geo-synchronous orbit.
  • The ribbon is kept taut due to the rotation of the earth (and that of the counterweight around the earth). At its bottom, it pulls up on the anchor with a force of about 20 tons.
  • Electric vehicles, called climbers, ascend the ribbon using electricity generated by solar panels and a ground based booster light beam.
  • In addition to lifting payloads from earth to orbit, the elevator can also release them directly into lunar-injection or earth-escape trajectories.
  • The baseline system weighs about 1500 tons (including counterweight) and can carry up to 15 ton payloads, easily one per day.
  • The ribbon is 62,000 miles long, about 3 feet wide, and is thinner than a sheet of paper. It is made out a material called Carbon Nanotube Composite.
  • The climbers travel at a steady 200 miles per hour, do not undergo accelerations and vibrations, can carry large and fragile payloads, and have no propellant stored onboard.
  • Orbital debris are avoided by moving the anchor ship, and the ribbon itself is made resilient to local space debris damage.
  • The elevator can increase its own capacity by adding ribbon layers to itself. There is no limit on how large a Space Elevator can be!

Frequently Asked Questions
  • Science Fiction or Science Fact?
    The Space Elevator was first proposed in the 1960's by a Russian engineer (Yuri Artsutanov) as a far-reaching engineering concept. The scientific principles underlying it are well understood and do not require any fictional inventions, except for the super-strong material required for its construction. Since existing materials are not strong enough to build the Space Elevator, it has been relegated to the status of science fiction, and as such appeared in several books, the most famous of which is Sir Arthur C. Clarke's The Fountains of Paradise. About 10 years ago, the materials issue was solved when Carbon Nanotubes were discovered, and the present Space Elevator design was conceived by Dr. Brad Edwards. This design is different from the science fiction Space Elevators, and is extremely close to being achievable. The Space Elevator is therefore 100% Science Fact, with some technological hurdles that still need to be crossed.
  • How much will it cost?
    A lot less than the Shuttle, or the International Space Station... The entire system can be built and deployed for under 10 Billion dollars, and since all operations happen at the ground station, it is very inexpensive to operate - roughly $100 per pound initially, and much less as volumes increase. Having such a capable launch system will do wonders for the manned launch program, that can now rely on having everything it needs waiting for it in orbit or on Mars. Since the manned program is by nature very expensive, such reductions in cost translate into huge savings, much larger than the cost of the Space Elevator.
  • What's holding the ribbon up?
    Imagine yourself spinning a weight at the end of a string. The string is kept taut by the motion of the weight, and the longer the string is, the more time it takes the weight to go around. Now imagine a string so long, it takes the weight an entire day(!) to make a single revolution. If you were to tie such an incredibly long string to the surface of the earth at some point, it would remain taut, and for people on the ground it would seem to simply hang down from the weight, as if by magic. An alien traveling by spaceship, on the other hand, will see a rotating planet with a long string hanging straight out - much like a carnival ride. (Put yet another way, if you account for the rotation of the planet, the string is hanging from the ground, and falling into the sky.
  • How do you get it up there?
    "Getting it up there" is often referred to as "deployment". The first elevator has to be launched by rockets. However, an elevator can make itself bigger (thicker) by hauling up new ribbon material. In this way, there is an option to rocket-launch only a lighter-weight elevator, reducing the number of required launches by a fair amount.
  • What happens if it breaks?
    The short answer is that (much like the string-and-weight example) the portion of the elevator above the break point flies outwards, whereas the portion below the break point falls down to earth. We have to remember that the whole ribbon weighs only about 1000 tons (about the same as a Saturn V rocket) and has the density and consistency of Saran Wrap?, so if it falls, instead of crashing down in one place it is distributed evenly around the entire planet, with each square mile getting about an ounce of debris. The overall effect will be like a very disappointing global ticker-tape parade - hardly a ground-shattering event.
  • What about space junk? hurricanes? lightning? terrorists?
    There are many risk factors the Space Elevator design has to factor in. The space junk risk is mitigated by having the anchor on a ship, and moving it around to avoid incoming pieces. (Space junk is mapped. The International Space Station is regularly moved around in the same manner). In addition, the ribbon structure is resilient to hits from small debris. Since the anchor is on the equator anyway, hurricanes are not a problem. Other weather phenomena such as lightning can be largely avoided by moving the anchor ship. Finally, man made risks (sabotage) are largely mitigated by having the Space Elevator anchored in a remote region, so its permimeter can be safely and effectively guarded.
  • What is the current state of Carbon Nanotube Composites (CNTCs) research?
    Yearly production of CNTs is increasing each year by a factor of 10. Single Wall Nanotubes (SWNT), which are the type we want, are becoming available in larger and large quantities. CNTCs are maturing very fast indeed. They are now as strong as the strongest materials available commercially, and there isn't a technological barrier to making them as strong as we need them.
  • Why isn't the government building one?
    This is the most important question of all, and why Elevator:2010 is here. There is no doubt that the promise of the Space Elevator is mind boggling. And here lies the problem - it requires a paradigm shift. 100 years ago, people thought Dirigibles where the only way to fly, and heavier-than-air flying machines are an odd-ball idea. Today, there is an almost unbreakable concept that you go to space with rockets, and there is a huge industry built around this concept. That's a lot of inertia to overcome, and it requires both technical research and public pressure. We're here to get the word out, to have as many people hooked on the Space Elevator concept as we can.
  • When do you think the Space Elevator will be built?
    We believe we can solve all the fundamental problems by the year 2010, and at that point building the Space Elevator will become a national priority project. It should then be possible to complete the construction of the first elevator by the year 2020.

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