Space Elevator -- Other options beyond ribbon/CNT?

[waimea]

I am just learning about space elevators and the proposed technology surrounding them -- why does it seem like the focus is only on carbon nanotubes and ribbons -- is there any discussion about other potentially viable alternatives? To be frank -- a "beam up me scotty" possibility, as in moving a payload along a cushion of some sort? When all is said and done, the popular space elevator version seems like an upgraded version of a ski lift, with all the exposure and vulnerability and clunkiness. Can anyone point me in the right direction regarding discussions of other space elevator ideas?

 

[nexium]

Hi waimea: As we move into the engineering phase of a prototype, each corpration needs to focus narrowly on that which they think will produce best results in a short time and reasonable cost. Last I heard, Dr Edward's team was most promising for a space elevator. One company is looking at a net as a variation of the ribbon. Boron nitride is the only fiber competing with CNT that I know of. The cost of the elevator is astronomical, unless we use a tether several times as strong as kevlar.<br /> Several alternative for getting up the first hundred miles are being kicked around, but as far as I know, most are minor improvements (maybe) over the Space Shuttle and Chemical rockets. I say maybe as prototypes have not been built.<br /> One company hopes to launch in 2005 from a platform up 20 miles supported by balloons. There is talk of a rail gun which is a linear induction motor. As far as I know this has not been demonstrated at speeds faster than a bullet train, nor for an almost vertcal rail.<br /> One visionary suggested a launch loop, thousands of miles long and 60 miles tall, which, I think also requires materials such as CNT or stronger by weight. <br /> Dr. Edwards expect to use lasar beams to transfer energy from Earth's surface to the climbers and elevator cars. If workable, larger scale may be practical. Neil

 

[windreaper]

There maybe is a way to face the material/financial/hr problems of the space elevator project:<br /><br />As Im learning from space.com article, its the unsolved budget issue that keeps the whole from going on in the first place. The sheer magnitude of this project might require us to leave the old "national" constraint thinking and to make it a really global project! There is research in all of inbound technologies the whole world over, including space transportations, yet it is just too expensive for one country alone to tackle, especially nowadays. Why, lets just throw it into one pool! <br /><br />Wouldnt this also be in the spirit of Clarke himself, the British who joined projects everywhere and since long prefers to live on Sri Lanka? Maybe the cold war also was the reason for him to put his ideas into a science fiction novel...<br /><br />The nature of the elevator itself just raises this attitude. A world wide space project that would enable even poor nations to put equipment in orbit would also help to pale the decades-old rich-poor nation quarries. It could be an instrument of peace, a step towards... <br /><br />Well, just my 2 cents worth.<br /><br />Greetings and Merry Christmas,<br />Wind

 

[scottb50]

From what I have heard of the Delta launch it was the first stage that shutdown too soon and didn't involve a problem with the second stage.<br /><br />What we need is ever evolving rocket engines and the only way to have them is to have enough demand for launchs. Good examples are the upper stage motor on the Delta-4, a direct descendent from the original RL-10 and Soyus that dates to the early fifties. The military paid their way. <br /><br />The SSME was specifically designed for multiple uses to attract industry, the first stage engines of the Delta are based on the SSME. <div class="Discussion_UserSignature"> </div>

 

[griffin021390]

i agree.<br />but i also have an idea for what they could do for space elvators: The cable could be made of a super conductor. The cable will have an electrical current running through it. Then the elevator box will have a hollow metal tube with a rubber insulator on the outside going through the middle of the box and the cable will run through the tube. The metal tube won’t have any current running through it so that it will be attracted to the cable. Since the metal is a conducting metal, it will create an inductive current through the cable allowing the elevator box to go up and down the cable riding the electric current in the cable. A generator will be used to create the induction current. <br /><br />Tell me what u think.

 

[vogon13]

I floated this idea a while back and the response was underwhelming, but I like it.<br /><br />Have a carbon filament come down to roughly 100 to 150 km from the earths surface (over the equator of course). Directly under the end of the tether, have a nice launch facility for Burt Rutan. Have a Spaceship One follow on craft launch from under the tether, climb and dock with it.<br /><br />Advantages:<br /><br />The toughest part to build and maintain, the part in earth's atmosphere, is gone.<br /><br />Rutan has apparently the cheapest technology to the altitude of the bottom of this tether.<br /><br />SS1 is moving at its slowest speed at the top of its' flight arc, easiest to manuver to the tether and dock at that time.<br /><br />When you want to return to earth, his craft doesn't care if it is on the original flight arc, or has been hanging on the tether for a month (re-entry wise). It will still happily come down at a max speed of Mach 3.<br /><br />Well?<br /><br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[josh_simonson]

MXER tethers do just that, only they rotate so they don't have to be in a geostationary orbit.<br /><br />One could also hang a mass driver under a high altitude balloon to eliminate most of the atmospheric friction and existing guns could do the job. Maybe JP should propose that, bet the brass would like an airship over kansas that could shoot to anywhere in the world in 20 minutes.

 

[rocketman5000]

"he cable could be made of a super conductor. The cable will have an electrical current running through it. Then the elevator box will have a hollow metal tube with a rubber insulator on the outside going through the middle of the box"<br /><br />I had a similiar idea. Sorta like a vertical climbing bumper car or electric train. Then now have designs of CNTs that conduct electricity well. I don't know if they can conduct ac and dc or not and what their resistance per meter would be. In my idea electricity would be sent up or down the wire using the CNT wires. the "car" would have a pick to the electricity and would use it to run motors. I am not sure of the material properties (UTS and such) of the electricity conducting CNT, but ideally would they could make up part of the mechanical structure of the wire. <br /><br />I know from the information I have read it would the laser concept is very energy inefficient. I believe this method (I haven't ran numbers though) would be much higher efficiency. If the direction of the current was correct it could also boost off the magnetic field of the earth to counteract drag and momentum lost due to released payloads.

 

[josh_simonson]

Actually the cable can't be conductive or it will wreak havoc on the earth's magnetic field. CNT are good conductors, and that may doom them from space elevator applications without insuated couplings or some other means of breaking it into electrically isolated pieces.

 

[mcbethcg]

It is theoretically possible to build structures that extend to the edge of space. Incorporate a 60 mile long linear accelerator into it. No problems with excessive acceleration with that length or atmospheric friction with that height.<br /><br />It would be cheaper than a space elevator to build and operate. It could be built with massive ammounts of existing materials.<br /><br />A billion dollars could buy the materials- but getting the work done at 60 miles altitude might be impossible. though.

 

[scottb50]

Why does it have to be a tether? Why not a Tug? Launch a big payload to a low orbit and use Tugs to intercept it. <br /> <div class="Discussion_UserSignature"> </div>

 

[griffin021390]

(To scottb50): <br />1.) because the point of a space elevator at least to me is to save fuel which u use icredible amounts of during the launch process.<br /><br />2.) because finding a metirial for the cable that is strong enough to lift several hundred tons for an hour or longer more than 2 times a month without breaking would be very difficult....That's why my idea (i think) would be so practicle, because instead of puting so much strain on the cable, all your using the cable for is basically an electrical track.

 

[josh_simonson]

Fuel isn't a big concern, the big things the elevator gets around is the need for expensive and dangerous rocket engines and heat shielding. If it was just a matter of fuel, it'd cost about $2 a pound to go to orbit.