My personal favorite space launch technology

[RafaelAustin]

Space Elevator Upstarts Settle Down To Business

"Detailed design work on the space elevator concept has been made possible through NASA's Institute for Advanced Concepts (NIAC).

One end of the cable would be attached to an offshore sea platform. The cable stretches up through the sky and outward into space for some 62,000 miles (100,000 kilometers) distance. On the space end of the cable - a counter weight.

Once in place, the competing forces of gravity at the lower end and outward centripetal acceleration at the farther end keep the cable under tension and stationary over a single position on Earth.

The outstretched cable can then be ascended by mechanical means. If a robotic climber slowly tools up to the far end of the cable, then releases from the line, it would have sufficient energy to escape from Earth's gravity well and zoom onward to the Moon, Mars, Venus, or asteroids.

A working space elevator can haul up large fragile structures such as solar power satellites, habitats, and payloads for the exploration and development of space."

[Andrew]

How do they get the cable up there?

[RafaelAustin]

^ [img]/phpBB/images/smiles/icon_smile.gif[/img]
Actually, I think the most efficient way is to produce the fibers in orbit aboard the 'anchor' station. Who knows, maybe the micro-G environment would be better for production anyway?

[Comixx]

Well, these books I'm reading by Peter Hamilton, The Reality Dysfunction series has space elevators. They move metalic asteroids into orbit and mine the asteroid itself for materials while using the newly hollowed asteroid for an industrial and transport station. They also use a second smaller asteroid for a counter-balance to damp down harmonic vibrations caused by traversing the tower.

How would they damp down the charges from the electomagnetic interactions with the Earth though?

_________________
Non-Geeky Gazer [img]/phpBB/images/smiles/icon_wink.gif[/img]




<font size=-1>[ This Message was edited by: Comixx on 2002-11-23 19:28 ]</font>

[Colt]

"Twenty tons of cable and reel would be kicked up to geosynchronous altitude by spacecraft to get the project started."

It would be easier to juts construct the cable in orbit and lower it down. "But it will burn up!" No it won't. It is going to be going very slowly compared to any re-entry object. You would just lower the cable down to the anchor-point and connect it there. Anyone interested in space elevators should read Kim Stanley Robinson's Mars series of books and Clarkes "3001: The Final Odyssey".

In the mars series the elevator orbiting the Earth was from a captured meteorite and the materials for the cable were taken from it. The one on Mars was made from one of the two moons (can't remember which) It has been a long time since I have read Green mars and the tiny bits of Red and Blue..

A space-elevator could be used in conjunction with a space catapult to almost completely dispense with rockets. -Colt

[Colt]

On 2002-11-23 19:26, Comixx wrote:
Well, these books I'm reading by Peter Hamilton, The Reality Dysfunction series has space elevators. They move metalic asteroids into orbit and mine the asteroid itself for materials while using the newly hollowed asteroid for an industrial and transport station. They also use a second smaller asteroid for a counter-balance to damp down harmonic vibrations caused by traversing the tower.

How would they damp down the charges from the electomagnetic interactions with the Earth though?

_________________
Non-Geeky Gazer [img]/phpBB/images/smiles/icon_wink.gif[/img]




<font size=-1>[ This Message was edited by: Comixx on 2002-11-23 19:28 ]</font>

Heh, yeah, someone said that if we ever had a space-elevator the cable/tower for it would be the biggest lightning rod in the world. [img]/phpBB/images/smiles/icon_biggrin.gif[/img] -Colt

[Donnie B.]

Methinks that Florida would not be the best location for the base station!

(I know, I know, it would have to be on the equator anyway...)

[Colt]

Florida should be nuked, too hot and a bunch of illegal immigrants. ;P Just joking of course, though I would not want to live there. It would not be that much difference putting it in Nevada or New Mexico and those places have tons of open desert, something falls off of the cable and it just lands there. Plus Florida is notorious for storms and Orbiter launches being delayed. I seriously doubt that a cable like the one we are talking about would take kindly to an atmosphere-high wall of wind and water slamming into it, think of the vibrations alone. -Colt

[David Hall]

A space elevator would have to be placed on the equator, because the upper anchor has to be in geostationary orbit. I remember from A.C.Clarke's The Fountains of Paradise that minor variations in the Earth's gravitational field have to be considered too.

[RafaelAustin]

Why not use the static charges for power? I've seen some sites that claim using the inherant charge that the carbon fibers would build up because of the magnetosphere to power the 'cable cars'.

[RafaelAustin]

And I think that the equitorial Pacific has been cited as the atmospherically most stable area to place a base station. Attitude jets would have to be placed on it to stabilize any harmonics and a substatial tower would be needed to withstand any hurricanes.

[SAMU]

Sorry to put a damper on this discussion but with NASA actually considering this concept I feel compeled to point out that in this concept the mass that is raised to the upper geosyncronous orbital point still has to be accelerated to the east to geosyncronous velocity. The only mechanism to apply this energy to the elevator mass is the cable. The result being that as the mass climbs the cable the cable and the "counterweight mass" will be drawn to the west and down. The more mass that is lifted, the further west (and down)the structure will be drawn. Obviously this renders the structure unstable and the concept unworkable even given the enormous advance in building material strengths this structure demands. Which is, by the way, 10,000 times greater in tensile strength than anything currently known to man.
I figured this out years ago when I read it in Arther C Clarke's "Fountains of Paradise". I like Clarke, but he missed it here.

I like the rail gun concept better because it is do able NOW with current materials at my estimated cost of 3 to 5 billion dollars, with cost overruns bringing the cost up to no more than 10 billion dollars max, and does not violate basic inertial law.

<font size=-1>[ This Message was edited by: SAMU on 2002-11-24 03:59 ]</font>

[xriso]

Indeed. If the elevator is mostly being used for going up (very likely the case), it will pull down the upper assembly a bit every time, due to conservation of energy.

You could use rockets to reposition the upper anchor every time, but... Now you're back to rockets again!

It's hard to get out of a gravity hole, and we don't have any ladders long enough to reach the "top".

<font size=-1>[ This Message was edited by: xriso on 2002-11-24 15:46 ]</font>

[Colt]

You could have ion engines (were stretching for new technology anyway) and have the cable transfer power up to power them, and even just one trip up it would be enough to supply the station at the top with plenty of fuel. [img]/phpBB/images/smiles/icon_smile.gif[/img] I imagine a fuel-pod would look something like a beetle climbing a thread. -Colt

[Comixx]

So, what I gather here is that, even if we could build a tower, instead of a cable, that was resistant to downward force, it would still pull to the west causing the end and counter-weight to arc downwards. That would mean you'd have to employ thrust at the counter-weight? Why couldn't you have the weight be of sufficient mass to resist any potential mass pulling laterally on the tower? Is the principle here (of the mass going up the tower) like a Hohmann transfer orbit, where the farther out from center it goes, the slower, which is why it pulls westerly?

I'm a graphic artist with an interest in this stuff, not a scientist, so please forgive my ignorance.

[SAMU]

You can illustrate the mechanics involved by taking a string with a ball on the end and swinging it in a circle. It doesn't have to be a fast flat circle, just enough to be viewable as a circle. You then have another ball with a hole in it to slide down the string. With the first ball swinging in a circle you have the second ball on the string in your hand. When you release the second ball to go down the string you can see how unstable it gets.

<font size=-1>[ This Message was edited by: SAMU on 2002-11-25 18:28 ]</font>

[Argos]

On 2002-11-24 00:37, Colt wrote:
Florida should be nuked, too hot and a bunch of illegal immigrants. ;P Just joking of course, though I would not want to live there.

Everybody's talking about nuking nowadays. This talk is dangerous. It slowly feeds back our worst complexes. Sometimes words get to materialize. Beware.

As to immigrants (Cubans and Mexicans I suppose), I think thay make Florida richer, for their art, culture and hard work [it's funny how nobody complains about the immigrants from Germany, Denmark, Scotland and so on...].

As to Florida being hot... OK I agree. It's dreadful. Just as the place I live.

Plus Florida is notorious for storms and Orbiter launches being delayed. I seriously doubt that a cable like the one we are talking about would take kindly to an atmosphere-high wall of wind and water slamming into it, think of the vibrations alone. -Colt

Have you heard about Marajo Island in South America? Well, I sincerely doubt if there's a better place on Earth for such venture. The Equator divides this Island into two equal parts. This means that the tower of the elevator would be located in the center of the Island, in a storm free, quake free, people free zone of the Earth.

Btw, US is going to use Brazil's Alcantara Launch Base, the most equatorial rocket launching site on Earth. As you see, Nasa knows geography.

Anyway, I don't think such an elevator will be built in the next 1000 years.

<font size=-1>[ This Message was edited by: Argos on 2002-11-26 06:55 ]</font>

[David Hall]

On 2002-11-26 06:27, Argos wrote:

As to immigrants (Cubans and Mexicans I suppose), I think thay make Florida richer, for their art, culture and hard work [it's funny how nobody complains about the immigrants from Germany, Denmark, Scotland and so on...].

Well, nobody complains about them now, because they've been with us long enough to become integrated. In truth, immigrants from just about any country to any other country have to deal with a certain amount of resistance. It seems to be just human nature to discriminate against outsiders, especially when you get a lot of them at once. But after a few generations they cease to be outsiders and become part of the culture. Just wait a century and it won't be a problem anymore.

Btw, US is going to use Brazil's Alcantara Launch Base, the most equatorial rocket launching site on Earth. As you see, Nasa knows geography.

Sounds great. Do you have any links on this? How are they planning on using it?

Anyway, I don't think such an elevator will be built in the next 1000 years.

I don't know about 1000 years, but I'd probably agree with 100. It would be a mammoth project, and not one to be taken until and unless it becomes both technologically and economically feasable. I think that eventually it might just become worthwhile to attempt. With the news that has floated around about it in the last few years, I've started to have a little more hope for the idea.

[TinFoilHat]

If you make the couter-weight mass on the end of the tether sufficiently heavy, the perturbations generated by pulling loads up the cable will be managable. When disturbed by pulling a load up the cable, the counterweight mass will tend to oscillate west-east like a pendulum. If you time the loads coming up and down the tether correctly, you can keep the oscillation under control.

A cable constructed of buckeytubes would have the tensile strength needed for such a tether, alwhough we can't yet make them in that length and quantity. We've learned a lot about how to make them in the last few years - I'll be suprised if someone isn't making bucky-tube cable commercially in 20 years.

[traztx]

How slow would the robotic crawler crawl up the elevator? If we want to launch something every 3 months, we would need to move up that cable almost 30 mph (assuming the crawler doesn't have to return to earth).

[Argos]

On 2002-11-26 08:36, David Hall wrote:

Btw, US is going to use Brazil's Alcantara Launch Base, the most equatorial rocket launching site on Earth. As you see, Nasa knows geography.

Sounds great. Do you have any links on this? How are they planning on using it?

US are working on an agreement with Brazil for general use of the Base. Bellow I give some links related to the Alcantara launching center.

http://www.spacetoday.org/Rockets/Sp...unchSites.html

http://ast.faa.gov/linfo_vsite/maps/detail.cfm?Fac_ID=2

http://www.fas.org/news/brazil/t95003a.htm

This one is in Portuguese. it brings a tiny photo (I hardly found any. I'm starting to suspect that they want to keep the place in secret. [img]/phpBB/images/smiles/icon_smile.gif[/img])

http://www.agespacial.gov.br/centrolanc.htm

And this one features a xenophobic group which claims that US are going to take possession of the site and buid a military base. Crackpots.

http://www.holycrossjustice.org/USbaseeng.htm

<font size=-1>[ This Message was edited by: Argos on 2002-11-26 12:52 ]</font>

[RafaelAustin]

On 2002-11-26 11:06, traztx wrote:
How slow would the robotic crawler crawl up the elevator? If we want to launch something every 3 months, we would need to move up that cable almost 30 mph (assuming the crawler doesn't have to return to earth).

When constructing the bands, slow moving crawlers would be used. But I believe most designs show the completed structure would be much faster. From Highlift Systems:

Once construction begins it will take six years to complete construction and launch the initial spacecraft. Two and a half additional years will be required to build up the ribbon to a 20,000 kg capacity. The operational space elevator will launch 5 ton payloads every day within fifteen years. Recent analysis also finds that the first space elevator could be built for $7 to $10 billion total, including launch costs, and a second elevator would cost a small fraction of the first. The first elevators could be financially self-supporting (including recovering the initial construction costs and the cost of borrowing this money) within the first 10 years of operation on the commercial satellite market. The recurring costs are: 1) climbers, 2) power beaming system operation, 3) low-Earth object tracking system operation, and 4) anchor operations. For the initial space elevator these recurring costs combined with repaying the initial capital investment would give us total launch costs of $100/kg ($45/lb or 1/10 to 1/100 of conventional systems).

Thanks so much everyone for your input!
Here are some other Space Elevator sites:

http://www.highliftsystems.com/

http://www.niac.usra.edu/files/studi...21Edwards.html

http://www.firstscience.com/site/articles/elevator.asp

http://www.spacedaily.com/news/future-01f.html

http://www.space.com/businesstechnol...or_001226.html

http://www.space.com/businesstechnol..._020327-1.html

[SAMU]

This high lift systems company seems to me to be nothing more than a slick con. Their site has a forum, and questions about conservation of angular momentum are utterly glossed over (with good reason, it won't work)). In addition to which their FAQ states that the cable deployment is to be begun by being "lowered" from low earth orbit (LEO). You can't "lower" anything from LEO any more than you can "drop" a rock from the Space Shuttle. You can set a rock on a reentry course but it will burn up with its orbital speed. I could go on and on about this. I just hope my tax dollars don't go into this con.

Though like most cons it probably won't get much from the gov. Just poor old widow women. That's a pity.

<font size=-1>[ This Message was edited by: SAMU on 2002-11-27 02:55 ]</font>

[daver]

On 2002-11-27 02:54, SAMU wrote:
This high lift systems company seems to me to be nothing more than a slick con. Their site has a forum, and questions about conservation of angular momentum are utterly glossed over (with good reason, it won't work)).

Are you sure about this? Did you do the math, or are you just waving your arms? Tidal drag and tension from the base station seem like they should restore any angular momentum lost by the beanstalk.

In addition to which their FAQ states that the cable deployment is to be begun by being "lowered" from low earth orbit (LEO). You can't "lower" anything from LEO any more than you can "drop" a rock from the Space Shuttle.

The article i read said lowered from GSO, not LEO. Big difference. However, if i were doing it, i'd try a tether from LEO first (not all the way to the ground, of course). This would test the tether in a space environment, and could be used to lower slightly the cost to orbit. Unfortunately (or maybe fortunately) the shuttle isn't equipped to dock with a tether. A tether (particularly a rotating tether) in MEO might be useful to study the effect of high energy protons on the tether material, and could be useful for reducing the cost to GSO (useful for when you start spinning the real beanstalk. Of course, all the intermediate tethers would need to be deorbited before the beanstalk could be constructed).

I could go on and on about this. I just hope my tax dollars don't go into this con.

Though like most cons it probably won't get much from the gov. Just poor old widow women. That's a pity.

<font size=-1>[ This Message was edited by: SAMU on 2002-11-27 02:55 ]</font>

I'm not convinced that it is a con. I don't think it's the best way to build a beanstalk (i'd like to see the materials used in terrestrial construction first, then maybe a pinwheel tether if that turns out to be stable (there was some doubt about this the last time i read about it)).

[cable]

there are cables nad cables.
this cable must be lightweight and still too strong, at least to support it's own weight.
looks like a cable's dream [img]/phpBB/images/smiles/icon_smile.gif[/img]