Concept art of a space elevator. Source: Lift Port Group(see part 2) So, what exactly is a space elevator? It's exactly what you'd imagine; an elevator that goes into space. Basically the ideas proposed for a space elevator consists of a "base station" that has a geosynchronous counterweight tethered to it.
The four basic elements required for such a concept are: the base station (as previously mentioned), a cable sometimes referred to as the "ribbon", climbers (the elevator portion), and the counterweight.
The base station could come in a variety of forms. One being a mobile form. The base would most likely be positioned in the ocean or another large body of water. Its mobility could be used to maneuver away from satellites and other orbiting objects but I think something as amazing
Concept art of a potential Base Station. Source: Lift Port Groupand "game-changing" as a space elevator would take precedence. It would be much simpler to change the orbits of everything else and use the cost/material advantageous method of a stationary base. A stationary base could theoretically have a significantly shorter, required cable length depending on altitude. A shorter cable could also reduce the required thickness of the cable as a whole, eliminating even more cost and materials necessary.
The technology for cable construction is not as far away as one might think. It is estimated that the tensile strength required for the tether would have to be in the range of 65-120 Gigapascals. To put it into perspective steel has a mere 2 GPa or less of tensile strength. Fortunately, the advent of carbon nanotubes has produced strands that could resist as high as 52 GPa before snapping and the theoretical capability is beyond 120 GPa. Mass production and creating large strands is currently an issue but the future looks optimistic as the demand for carbon nanotubes is way beyond just space elevators. We're talking computers, planes, bridges, rockets, and other materials in general. Demand is high and likewise research too.
Concept design of a Climber. Source: Lift Port GroupClimbers would serve as the "elevator" of the system but due to a construction requiring a larger center than tips ( necessary because of centripetal forces) it would not use typical elevator methods. Hence, the name climbers. The proposed designs, friction held rollers and robotic arms with hooks, present less of a challenge than actually powering the climbers. The best method I've read about so far has been powering it by lasers. The concept would be similar to a laser powered solar sail (look for a post about this in the upcoming future). This technology is still in its infancy and isn't very efficient currently but it looks very promising.
Lastly, we have the counterweight. Many have pushed the idea of an asteroid as a counterweight but I happen to like the potential of the alternative: a space station. Not a whole lot to explain here and I'm sure you could imagine some of the capabilities a space station on top of a space elevator could have. I.E. spaceport, research labs, weightless space construction, space hotels, etc. etc.
Lifting the cable into space presents a bit of a problem but Bradley C. Edwards (former Director of Research for the Institute for Scientific Research) has proposed a highly efficient method for doing so. The method involves creating an initial, "seed" cable that is very thin and launching it first. Next, small climbers would progressively add thicker and thicker cables from the ground up until the desired proportions are reached.
Initial costs are also relatively "affordable" for a system similar to the seed cable, starting at an estimated $5 billion.
My next post will concern the advantages and the costs that a space elevator would have in more, specific depth. I invite you all to come back and read it and to also post any questions or comments that you would like to see addressed in the next article.