Space Elevator: High Hopes, Lofty Goals

Yahoo! News ^ | 9/17/03 | Leonard David

[r9etb]

Now projected to be on the order of a $6 billion investment, the first space elevator could quickly reduce lift costs to $100 per pound. That far outstrips todays pricey launch costs of roughly $10,000 to $40,000 per pound, depending upon destination and choice of rocket launch system.

Whatever the idea's merits, I really doubt that $6 billion would even begin to touch this problem.

You need to drop at least the initial fibres down from geosynch, and it'd probably cost that much just to boost the fibres up that high in the first place.

[Phantom Lord]

The young boys of South Park attempted to build a ladder to Heaven.

The Japanese found out and built their own ladder to Heaven.

And the Japanese won the race to Heaven.

[Constitution Day]

[PatrickHenry]

PING. [This ping list is for the evolution side of evolution threads, and sometimes for other science topics. FReepmail me to be added or dropped.]

[Dimensio]

The question still remains, however. Should we bomb heaven?

[A Broken Glass Republican]

What happens when this thing breaks and falls back down to earth? That would be one NASTY towell snap impact at the end.

[A Broken Glass Republican]

We'd better bomb heaven if we're serious about getting Saddam. He's up there hanging-out with all the Mormans.

[js1138]

I suspect that in the foreseeable future, the threat of terrorism will force the construction of a fail-safe cable with numerous landfalls, any one of which could be cut without bringing down (or up, as the case may be) the structure. Of course there may be less drama in breaking a structure that will fall up.

[Atlas Sneezed]

You need to drop at least the initial fibres down from geosynch, and it'd probably cost that much just to boost the fibres up that high in the first place.

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Interesting thought. Suppose you had a roll of the stuff (26,000 miles long), just a thin thread used as scaffolding to lift the rest of the main cable. You boost up the thread to geosynch. It happily floats there in one place. Now, you start unrolling it, and it starts pulling down on the roll, because the stuff lower than geosynch is pulled harder. Thus, you need to have a similar counterweight to extend beyond geosynch quite a distance (this can either be long, light and expensive, or short and very heavy).

When you lift stuff, you need to have enough excess counterweight out beyond geosync to create adequate tension to balance the load being lifted.

[LibWhacker]

Good point.

What was the name of that experiment a few years ago where shuttle astronauts tried to unreel a long cable while in orbit in order to generate electricity? That cable started to gyrate around uncontrollably and eventually broke loose from the shuttle. Did they ever figure out what caused that? I never heard.

It seems to me that whatever caused it could have a major deleterious impact on any attempt to lower a much, much longer cable down from orbit! Anyway, I hope they do figure it out before they try to build a space elevator -- which I'd like them to do asap.

[KellyAdmirer]

Now projected to be on the order of a $6 billion investment

I believe the shuttles were projected to be a $5 billion investment.

[r9etb]

When you lift stuff, you need to have enough excess counterweight out beyond geosync to create adequate tension to balance the load being lifted.

It's not tension, but you're close. It's tether dynamics: you need to boost mass outward just to keep the center of mass of the system at geosynch altitude. The whole thing will remain basically vertical, and the whole mess will orbit at the speed dictated by whatever altitude the the center of mass is at.

If the center of mass raises or lowers, the cable will drift west or east.

BTW, this thing has to be done at the equator....

[A Broken Glass Republican]

BTW, this thing has to be done at the equator....

I'd prefer a few hundred miles off the equator. Make for the greatest ride on earth! Well...Attached to earth.

[r9etb]

What was the name of that experiment a few years ago where shuttle astronauts tried to unreel a long cable while in orbit in order to generate electricity?

It was called the Tethered Satellite System.

That cable started to gyrate around uncontrollably and eventually broke loose from the shuttle. Did they ever figure out what caused that? I never heard.

It didn't gyrate around. It just suddenly snapped. IIRC, the post-failure investigation found a weakening of the copper core of the tether, probably caused by a kink. I think the weakness was exacerbated by the fact that over 2 Amps were running through the line, at a pretty high voltage.

[r9etb]

I'd prefer a few hundred miles off the equator. Make for the greatest ride on earth! Well...Attached to earth.

My lunch just rose in protest at the mere thought.... ;-8<<<<<::...

[Doctor Stochastic]

What about differential wind action on account of altitude.

Are carbon nano-tubes resistant to oxidation in atmospheric ozone? Are they bacteria-resistant?

(26000 miles)*(3 feet)*(1/1000 inch)* (1.7 gm/cc) = 3067 tons.

[LibWhacker]

A meter wide, thin as a newspaper, one-fifth the weight of steel, 60,000 miles long . . . Think humungous snicker-snack saw blade, whipping wildly about as it fell, wrapping itself around the earth a few times as the planet rotated beneath it. Whole forests levelled, cities sliced and diced, crops destroyed . . . LOL, just kidding! :-)

[AngryJawa]

BTW, this thing has to be done at the equator....

I may actually hurt myself while trying to think of an equatorially-situated, politically-stable country in which to base this project...

[r9etb]

Are carbon nano-tubes resistant to oxidation in atmospheric ozone?

I don't know about Ozone ()₃), but I do know that atomic oxygen (plain old O) just dearly loves to stick to carbon.

They'd have to coat the cable with something.