Space Elevator, Can we build one? Options

[imran]

This article says it might be possible.

A Hoist to the Heavens

[RNeuhaus]

Very interesting and it is a new paradigm to conquer to space. The article is worth to be read and I seems that it is between the fiction science and reality unless some technical leaders says that this project is feasible. Carl Sagan has already dreamed of it.

Rodolfo

[dvandorn]

Alas, materials technology just isn't up to it yet. The only materials we've ever come up with that would be strong and flexible enough to use to build a space elevator can currently only be produced in strands measured in microns, and no one has a really good idea of how to practically put them together into larger structures.

When (if ever) the materials technology is up to it, it's a good idea, though.

-the other Doug

[Bob Shaw]

A-a-a-a-ges ago there was a special issue of the JBIS which had a long look at elevators. There are actually a whole range of smaller alternatives using arcs and rotating structures, all of which have considerable bearing on airless worlds. On Earth, I'm not so sure - weather, terrorism and criminal stupidity all militate against a Sword of Damocles tens of thousands of miles long!

[jaredGalen]

I read an article over the past few days that spoke about an advance in manufacturing Carbon nano tubes on a large scale.

This is just one further step in perhaps producing the materials needed for the space elevator idea.


New Scientist had it too but I can't find it at the moment.
http://msnbc.msn.com/id/8976160/

[edstrick]

Also, about a year ago, another group was making single-molecule nanotubes up to a foot long. Not the perfect tubes, but ...

[Guest_Richard Trigaux_*]

Although conceptually simple and fascinating, the space elevator raises many issues, some already discussed above.


-the strand would have to withstand heavy horizontal forces when hoisting a vehicule, westwards when ascending, eastward when descending.

-The hoisted vehicule would need a week to travel all the height, if it travels at speeds comparable to railways.

-On the other hand the vehicule would need to travel very fast, to preserve passengers from radiation belts.

-Thus it would need a very large source of power, comparable to a rocket. So we could really save energy if there is a way to recover the energy of descending vehicles. Otherwise the overall energy is not better than with rockets.

-The strand will need to be electrically insulating, otherwise it would create a gigantic short circuit beteween the ground and the ionosphere, with unpredictable consequences. (A very predictable one would be that the strand would burn in a flash)

-For this reason we cannot use a trolley along the strand, to electrically feed the ascending vehicle (or to recover the energy of the descending vehicle).

-We can no more use an ancilary cable pulling the vehicle along the strand. Such a cable would rub against the main cable, or twist around it (with forces multiplied by the 60 000kms length) and move at hypersonic speed into the atmosphere.

-The strand would wear is space, from micrometeorites impacts or orbital objects impacts. This would appear, not much as a loss of resistance with time, but as a global loss of reliability.

-Massive use of this system would result into lenghening the day-night period.


So the idea of the space elevator is not so simple... I do not say that there are no solutions for the above problems, but what I think I reserve it for a future fiction story to be published.

[RNeuhaus]

More information about Carbon Nanotube Sheets, click here.
Now, it is already useful for some space applicacions:
Due to strength normalized to weight is important for many applications, especially in space and aerospace, and this property of the nanotube sheets already exceeds that of the strongest steel sheets and the Mylar and Kapton sheets used for ultralight air vehicles and proposed for solar sails for space applications, according to the researchers.

Rodolfo

[Guest_Richard Trigaux_*]

More information about Carbon Nanotube Sheets, click here.
Now, it is already useful for some space applicacions:
Due to strength normalized to weight is important for many applications, especially in space and aerospace, and this property of the nanotube sheets already exceeds that of the strongest steel sheets and the Mylar and Kapton sheets used for ultralight air vehicles and proposed for solar sails for space applications, according to the researchers.

Rodolfo

A hot air or gas baloon for a venusian lander could use carbon fabrics too. (Perhaps even not nanotubes) as no plastic will do.

[Guest_Richard Trigaux_*]

More information about Carbon Nanotube Sheets, click here.


Rodolfo

Hey, it seems that they really advanced, from lab protos to useable products. Not yet strong enough for the space elevator, but already superior to any other.

[RNeuhaus]

Hey, it seems that they really advanced, from lab protos to useable products. Not yet strong enough for the space elevator, but already superior to any other.

Good to hear from your comments since I am just starting to learn this new technology. However, there is still lots of doubts about this feasibility. The good thing is that there are many man who are dreaming and working to achieve it.

Rodolfo

[imran]

Good to hear from your comments since I am just starting to learn this new technology. However, there is still lots of doubts about this feasibility. The good thing is that there are many man who are dreaming and working to achieve it.

Rodolfo

The good thing also is that NASA isn't just brushing this off as some science fiction dream. The author received a grant from NASA's Institute for Advanced Concepts so to me this is a good sign. When this happens is anybody's guess but I think we're moving in the right direction.

[RNeuhaus]

I still am not able to figure it out on how the rope is kept tight and upward.

Anything in the space, in the exosphere zone, has nil gravity. How can the geostationary keep the cable outwards?

Then mi first tought to solve this case is that this is due to the centripetal force originated by the Earth's rotation. This will satisfy the Newton's Third Law of Motion, Isn't it? The total weight mass to put there is 600 TM is to compensate the weight that the rope and elevator might weight? The first geostationary at 36K Km is utilized to stabilize the inertia between two extrems points: on the floor and the other geostationary at 64K Km.

Is that a simple explanation so that the people understand on how the cable, and geostationary along with the 20 TM of space elevator won't fall off do to the Earth's gravity. Please correct me if I am wrong

Rodolfo

[Bob Shaw]

Rodolfo:

As I understand it, the principle behind space elevators is fairly simple.

Although the ends (or indeed any point) of the cable are certainly *not* in orbit, the centre of mass *is* - and at GEO. To make the thing work you need as much above, as below, so as to keep the whole thing balanced. In practice, any cable would have to be actively guided down to earth, while the GEO mass would be sufficiently high as to balance the cable. The structure has to be sufficiently strong as to support it's own weight and that of the payload, hence the need for exotic materials. If things go badly wrong, then the thing falls - this is *not* a good idea!

You *don't* need the whole shooting match to get many of the benefits - as I mentioned before, arcs and rotating columns will also work, especially in airless environments. What you probably *do* need, however, is an active space-based industrial infrastructure, which to my mind implies exploitation of NEO objects for mass and materials.

Bob Shaw

[RNeuhaus]

Bob: Now I understand it.

It is obvious that the cable must be very exoctic to witshtand a weight of over than 600 TM. I have not seen any rope able to hold up an weight of almost Boeing 777-200 airplanes. I haven't heard of the others funny things such as arcs and rotating columns. Well, with the time, I will discover them.

Anyway, thank you for your input.

Rodolfo