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European Space Agency engineer Age-Raymond Riice as developed a remarkably simple way to propel a space elevator upward with a series of rhythmic jerks.  (Source: BBC)
A new method could help realize dreams of a space elevator

A space elevator has been a long standing dream of many in the science and tech community.  Conceived by Russian scientist Konstantin Tsiolkovsky in 1895 and popularized by author Arthur C. Clarke, many believe the idea holds a great deal of real world promise, and may eventually provide the cheapest way to transport people and goods into space.  With many countries such as Japan, the ESA, and the U.S. finally getting serious in a race to become the first nation to develop a space elevator, enthusiasm is at a high.

Unfortunately, though, much of the materials and methods needed to build such an elevator are infeasible.  While carbon nanotubes could allow for a cable strong enough to hold a space elevator in theory, one key problem is how to propel the elevator along the cables into space.

Among the previously suggested methods of powering the climber into space were beaming microwave or laser power, or even concentrated solar power to the climber; but all these efforts have a long ways to go before being close to being feasible.

However, a remarkably simple idea proposed at the Second International Conference on Space Elevator and Tether Design in Luxembourg could hold the key to powering the space elevator.  European Space Agency ground station engineer Age-Raymond Riise showcased a remarkably simple propulsion method which uses a series of rhythmic jerks to propel a device upwards along a taut cable.

For his demo he tied brushes with their bristles pointing down, representing the elevator cabs around the broom stick, representing the elevator cable.  As the brushes pointed downward, they required less force to slide up than to slide down.  The assembly slid up and down along the broomstick, but experienced a net upwards motion, slowly climbing to the top of the broomstick.

The novel new method holds great promise as similar jerking motion could be applied to raise the elevator on a full-sized design, in theory.  The key technical challenge would be designing a cable strong enough to withstand the heat and forces exerted on it by the atmosphere. 

However, advocates argue that with payload costs still remarkably high, the financial and social incentives for building a space elevator are enormous.

Building a space elevator could enable novel new industries.  Describes Benoit Michel of the Catholic University of Leuven, a conference attendee, "From my point of view, the space elevator project is important because it enables a far more directly useful project - installation of large space solar power satellites around the Earth to provide continuous, cheap, CO2-neutral, environmentally friendly energy.  I firmly believe that the next century will have a large space-based industry and that industry will be the main energy provider for the whole mankind."

Mr. Riise has been approached by commercial aerospace terms about his idea and is in talks with them over terms.



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RE: A bit misleading
By Tyndel on 1/6/2009 12:05:09 PM , Rating: 2
However, what is the feasibility of moving that much mass up and down to gain a few feet/yards of upward movement per convulsion? How high up does the climber have to be before the vibration is changed to convulsion?

It seems, to me, to put some major strain on the anchor and would mean the other end of the cable couldn't be attached to a semi fixed location like a space station held in place a large part by centrifugal force canceling some of the gravity playing on the cable itself.

While any sort of cable based space elevator would require some room for play at the base, I would think a car running on tracks up the side like a train would be more feasible. Though if this were possible there would be very little to limit the size of the load that could be transfered upwards once it did get to the convulsion stage.


RE: A bit misleading
By masher2 (blog) on 1/6/2009 3:02:26 PM , Rating: 4
> "I would think a car running on tracks up the side like a train would be more feasible"

What do you power the car with? If you carry your own chemical fuel, you're back to the rocket equation, and the incredibly poor fuel-to-payload ratio thereof. You could try beamed power if you can deal with the focusing, generation inefficiencies, and atmospheric absorbtion issues, or you can try to carry a nuclear reactor aloft with you. That's about your only options.

This is a fresh new approach. Quite probably impractical...but still valuable for consideration.


RE: A bit misleading
By Reclaimer77 on 1/6/2009 4:43:00 PM , Rating: 1
The whole idea of the space elevator in itself is a crock. This approach is like trying to perfect a better screen door for a submarine.


RE: A bit misleading
By Sanity on 1/6/2009 5:30:51 PM , Rating: 3
Well as soon as you perfect a safe anti-gravity drive that can get us into orbit, and runs off of 6 AA batteries, let us know.

And your analogy is a crock. 0.o


RE: A bit misleading
By Tyndel on 1/6/2009 5:32:50 PM , Rating: 2
Seems to me electricity would be the most obvious solution. Beaming either microwave or laser is just too inefficient.

One of the advantages one could expect from having a space elevator and station would be a cheap efficient way of sending converted solar energy to earth without having to use beaming at all. And if we are already generating electricity at the top and sending it down why not just use, that, to power the climbers?

We are likely, as close to an ambient temperature superconductor(currently ~212K), as we are to the tinsel strength required to hold a space elevator together.


RE: A bit misleading
By masher2 (blog) on 1/6/2009 5:46:27 PM , Rating: 2
> "Seems to me electricity would be the most obvious solution."

Work out the weight of 35,000 km of high-power cable and insulation. Added to the tower, that's a substantial consideration. Also, the line losses over that length are astronomical. There's a reason most power plants are within a few hundred miles of the areas they serve.

Still, some combination of ultra-HVDC transmission and possibly using the cable itself as a conductor might turn out to be feasible.


RE: A bit misleading
By albundy2 on 1/7/2009 3:57:31 PM , Rating: 2
cnt's are conductive correct? cnt's are also the only trully feasable material to construct the cable correct?
iirc cnt's are also one of the best, if not the best electrical conductor. [i beleive i read that here, in a past article.] it would then make the most sense to use the cable as the/an energy source.

i was thinking while reading this article, why not use a helium baloon to power/assist the first few miles up. it would at least shed some weight until the atmosphere, wind or whatever negated the benefit.


RE: A bit misleading
By Gestahl on 1/14/2009 3:24:02 AM , Rating: 2
While CNT's may be conductive, and one day made strong enough for such a project... this isn't the case just yet. When claims are made about strong materials for structural applications, they seem frequently to neglect the elementary science of scale. Just because it is possible to produce a nanotube of carbon which has a calculated strength of 130 GPa and a measured strength approaching that value, it does not mean that this can be translated into a fibre of a length visible to the naked eye, let alone the 120,000 km needed to begin thinking about a space-elevator. Estimating a cable material with a tensile strength/mass ratio of at least 130 GPa/(1300 kg/m^3) would be required to support such dreams.

Assuming we do find a material with a tensile strength strong enough to support itself across the vast distance from surface to <geo orbit, there are other issues that come into play. Corrosion is a major risk to any thinly built tether (which most designs call for). In the upper atmosphere, atomic oxygen steadily eats away at most materials. A tether will consequently need to either be made from a corrosion-resistant material or have a corrosion-resistant coating, adding to weight. While there are known materials (such as gold and platinum which are practically immune to atomic oxygen... or a more common metal such as aluminum which is damaged very slowly, could be repaired as needed)

Also we have the effectiveness of the magnetosphere to deflect radiation emanating from the sun decreasing dramatically the further away from the surface the tether/cable/tower is. This ionizing radiation may cause damage to materials within both the tether/cable/tower and climber(s).

Until these issues can be resolved, while pulling together the many other variables, the dream of a space elevator is nothing more than that, a dream to science geeks (myself included).


RE: A bit misleading
By wordsworm on 1/7/2009 4:41:48 AM , Rating: 3
quote:
If you carry your own chemical fuel, you're back to the rocket equation, and the incredibly poor fuel-to-payload ratio thereof.


Something to make up for my Texan bashing - think "nuclear powered car". Can't really make a rocket that uses nuclear thrust, but since climbing an orbital tower would require mechanical energy it would be quite 'easy' to utilize nuclear power to send something into orbit.

I still prefer the idea of using maglev space launches. Surely it would be cheaper. You only need about 4mm of track, and if you could launch it 10km from sea level, a lot of the issues of friction (with the rest of it being encased in a vacuum) could be addressed. I can't help but think it would be a heck of a lot safer than an orbital tower to boot.


RE: A bit misleading
By jlips6 on 1/8/2009 4:57:14 PM , Rating: 2
perhaps this is just me displaying my ignorance, but why not use an improvised version of a counterweight system? line going down one side, then the opposite side.
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