The Space Elevator
Created | Updated Jun 6, 2003
INTRODUCTION
The Space Elevator, one of many children of science fiction now venturing into science fact, envisions an entirely new method of allowing we inhabitants of planet earth to escape into the void beyond. While previously, massive amounts of energy have been exhausted flinging rockets, and shuttles, into space, the space elevator promises to deliver us into space for only a fraction of the cost in energy, materials, and training.
Imagine a tower, fifty kilometers high. Today, our tallest buildings (two of which have recently been destroyed, of course) are still under a kilometer high. Affixed to the top of this imaginably tall tower is a cable, extending far beyond the eye's ability to resolve it, up, in fact, to space itself, a geosynchronous orbit at 35,786 km. Here, we reach a satellite, a space station, the central point for our elevator. Beyond this, we extend further, up to the 'anchor' point; perhaps an asteroid, manouvered into place for this very purpose. And that, is pretty much it. The space elevator.
CONSTRUCTION
The space tower, the 50km high earth anchor for the elevator, would be built along equatorial lines, for two major reasons. Primarily, the orbit of the station has to match both the direction and velocity of the earth's spin, something only an equatorial siting would allow for, and also, equatorial climates tend to be free of the large storms and hurricanes that could threaten the high-altitude sections of the cable.
On the other end of the line, the anchor asteroid similarily serves a double purpose. It acts as a counterweight, both preventing the cable from falling to earth under the action of gravity, and also shifts the cable's centre of mass to geosynchronous altitudes; causing the elevator to orbit at a speed matching the earth's natural spin.
Along the line, possibly utilising one or many seperate 'tracks' would run electromagnetic 'trains'. These would accelerate up the cable, to give a journey time of possibly 5 hours from earth to space. On the way down, similar forces would be applied to decelerate the train, preventing it from crashing into the tower. Naturally, any kind of frictional driven vehicle would prove to have too great a level of wear and tear on the cable itself.
TECHNOLOGY
As is usual for almost any revolutionary ideas science or technology, all is not as simple as it seems. Our primary setback lies in the construction of such an elevator, both in the tower and cable sections. The tower itself would, as previously mentionned, far outsize any previous construction known to man. While it is expected that current standards is science and engineering would allow the construction of towers over 1km high, 50km is a rather large step up, and, even if we were to be able to build it, the cost would be far too high to be acceptable currently. As such, the focus of research would need to be on creating materials that would allow such construction of a far cheaper and accessable scale, as well as boosting engineering stability.
The cable, while in foresight being the most difficult aspect of the elevator to acheive in real life, may actually be the easiest. Recent development of carbon nanotube, an artificially created molecule of carbon which promises to bring advances in many fields, provides a material almost perfectly suited to use as a tether cable. Common materials tend to have tensional strengths not exceeding 20 GPa (giga-pascal). Some, such as diamond, graphite, and quartz fibres, have demonstrated strengths above this, and could possibly come close to the estimated strength of 62 GPa necessary for a space elevator. Carbon nanotube, however, has a tensional strength of around 200 GPa, clearly above both the tensional strengths of all other known materials and the reccomended strength for a space elevator.
The trains, magnetic vehicles for transporting people and goods up and down the cable, are also a technology which is in development. Recent experiments in 'maglev' vehicles have been successful, and are already in suggestion for common ground trains, as well as launch tracks for conventional space vehicles. In Japan, America, and Germany, magnetically operated trains are beginning to move into the commercial arena. At the same time, the amount of electricity needed to operate a maglev is decreasing- it is only a matter of refinement to create a 'lift' for the space elevator.
If all these technological constraints can be overcome, the possibility of building a space elevator is solely one of engineering. However, this does also present it's own challenges. Take, for example, the anchor asteroid. Too large, and it may not want to move, putting too great a strain on the tether. Too small, and it may move too fast, casuing the whole assembely to come burning up in the earth's atmosphere. Nevertheless, these precise calculations are the kind that NASA, ESA, and all foreign counterparts have been dealing with for years, and they have for the most part been overcome.
ECONOMICS
Living, as we do, in a capitalist society, where, increasingly, every expense must be justified, scrutinized, and torn apart by all and sundry, it may seem that the principal obstacle in the way of the space elevator is not the science of physics, but the science of economics. We shall therefore briefly look at how the space elevator's books balance.
The construction of a space elevator could be, without doubt, one of the most expensive projects known to man. Simply the launch of enough space shuttles to launch the manufacturing equipment for the tether into space would cost millions, and then you have the cost of shipping the materials to make the tether out of. Alternatively, of course, we could attempt to manouver an asteroid into place to provide the raw material, but this would also be an incredibly large undertaking. Firstly, we would need to identify an asteroid containing the right elements. Then we have to move it into place, and develop the correct refining capabilities to mine an asteroid. Also consider that, unless we happen to find a suitable rock floating around the inner planets somewhere, the nearest ready source of asteroids is just this side of Jupiter. The question, therefore, is how quickly the costs would be recouped. Per kg, the cost of sending material up into space at the moment is approximately $22,000. Sending the same material up a space elevator would average a staggering $1.50. in that at least, the space elevator shows it's promise. But the real question is what profit is to be made from sending material up into space, or bringing it down again. A space elevator would certainly bring benefits to science, where numberous projects could be carried out much easier in the bleakness of spac. It would also allow the creation of off-world manufacturing stations, again, something that could benefit from the lack of gravity and air friction, and someting that would also bring great benefits to the environment. The possibility also opens up of mining the moon, and other planets in our solar system. As such, and in conclusion, we find that in the long run, the space elevator would be an incredible economic asset- but people have a tendency to prefer to think in the short term, and thus it is highly unlikely, in my opinion, that a space elevator is going to be built any time in the near future, despite the fact that the technology to build one may already exist.
The Space Elevator, one of many children of science fiction now venturing into science fact, envisions an entirely new method of allowing we inhabitants of planet earth to escape into the void beyond. While previously, massive amounts of energy have been exhausted flinging rockets, and shuttles, into space, the space elevator promises to deliver us into space for only a fraction of the cost in energy, materials, and training.
Imagine a tower, fifty kilometers high. Today, our tallest buildings (two of which have recently been destroyed, of course) are still under a kilometer high. Affixed to the top of this imaginably tall tower is a cable, extending far beyond the eye's ability to resolve it, up, in fact, to space itself, a geosynchronous orbit at 35,786 km. Here, we reach a satellite, a space station, the central point for our elevator. Beyond this, we extend further, up to the 'anchor' point; perhaps an asteroid, manouvered into place for this very purpose. And that, is pretty much it. The space elevator.
CONSTRUCTION
The space tower, the 50km high earth anchor for the elevator, would be built along equatorial lines, for two major reasons. Primarily, the orbit of the station has to match both the direction and velocity of the earth's spin, something only an equatorial siting would allow for, and also, equatorial climates tend to be free of the large storms and hurricanes that could threaten the high-altitude sections of the cable.
On the other end of the line, the anchor asteroid similarily serves a double purpose. It acts as a counterweight, both preventing the cable from falling to earth under the action of gravity, and also shifts the cable's centre of mass to geosynchronous altitudes; causing the elevator to orbit at a speed matching the earth's natural spin.
Along the line, possibly utilising one or many seperate 'tracks' would run electromagnetic 'trains'. These would accelerate up the cable, to give a journey time of possibly 5 hours from earth to space. On the way down, similar forces would be applied to decelerate the train, preventing it from crashing into the tower. Naturally, any kind of frictional driven vehicle would prove to have too great a level of wear and tear on the cable itself.
TECHNOLOGY
As is usual for almost any revolutionary ideas science or technology, all is not as simple as it seems. Our primary setback lies in the construction of such an elevator, both in the tower and cable sections. The tower itself would, as previously mentionned, far outsize any previous construction known to man. While it is expected that current standards is science and engineering would allow the construction of towers over 1km high, 50km is a rather large step up, and, even if we were to be able to build it, the cost would be far too high to be acceptable currently. As such, the focus of research would need to be on creating materials that would allow such construction of a far cheaper and accessable scale, as well as boosting engineering stability.
The cable, while in foresight being the most difficult aspect of the elevator to acheive in real life, may actually be the easiest. Recent development of carbon nanotube, an artificially created molecule of carbon which promises to bring advances in many fields, provides a material almost perfectly suited to use as a tether cable. Common materials tend to have tensional strengths not exceeding 20 GPa (giga-pascal). Some, such as diamond, graphite, and quartz fibres, have demonstrated strengths above this, and could possibly come close to the estimated strength of 62 GPa necessary for a space elevator. Carbon nanotube, however, has a tensional strength of around 200 GPa, clearly above both the tensional strengths of all other known materials and the reccomended strength for a space elevator.
The trains, magnetic vehicles for transporting people and goods up and down the cable, are also a technology which is in development. Recent experiments in 'maglev' vehicles have been successful, and are already in suggestion for common ground trains, as well as launch tracks for conventional space vehicles. In Japan, America, and Germany, magnetically operated trains are beginning to move into the commercial arena. At the same time, the amount of electricity needed to operate a maglev is decreasing- it is only a matter of refinement to create a 'lift' for the space elevator.
If all these technological constraints can be overcome, the possibility of building a space elevator is solely one of engineering. However, this does also present it's own challenges. Take, for example, the anchor asteroid. Too large, and it may not want to move, putting too great a strain on the tether. Too small, and it may move too fast, casuing the whole assembely to come burning up in the earth's atmosphere. Nevertheless, these precise calculations are the kind that NASA, ESA, and all foreign counterparts have been dealing with for years, and they have for the most part been overcome.
ECONOMICS
Living, as we do, in a capitalist society, where, increasingly, every expense must be justified, scrutinized, and torn apart by all and sundry, it may seem that the principal obstacle in the way of the space elevator is not the science of physics, but the science of economics. We shall therefore briefly look at how the space elevator's books balance.
The construction of a space elevator could be, without doubt, one of the most expensive projects known to man. Simply the launch of enough space shuttles to launch the manufacturing equipment for the tether into space would cost millions, and then you have the cost of shipping the materials to make the tether out of. Alternatively, of course, we could attempt to manouver an asteroid into place to provide the raw material, but this would also be an incredibly large undertaking. Firstly, we would need to identify an asteroid containing the right elements. Then we have to move it into place, and develop the correct refining capabilities to mine an asteroid. Also consider that, unless we happen to find a suitable rock floating around the inner planets somewhere, the nearest ready source of asteroids is just this side of Jupiter. The question, therefore, is how quickly the costs would be recouped. Per kg, the cost of sending material up into space at the moment is approximately $22,000. Sending the same material up a space elevator would average a staggering $1.50. in that at least, the space elevator shows it's promise. But the real question is what profit is to be made from sending material up into space, or bringing it down again. A space elevator would certainly bring benefits to science, where numberous projects could be carried out much easier in the bleakness of spac. It would also allow the creation of off-world manufacturing stations, again, something that could benefit from the lack of gravity and air friction, and someting that would also bring great benefits to the environment. The possibility also opens up of mining the moon, and other planets in our solar system. As such, and in conclusion, we find that in the long run, the space elevator would be an incredible economic asset- but people have a tendency to prefer to think in the short term, and thus it is highly unlikely, in my opinion, that a space elevator is going to be built any time in the near future, despite the fact that the technology to build one may already exist.
