BS: Space Elevator in work

Subject: BS: Space Elevator in work
From: GUEST,beardedbruce
Date: 23 Sep 08 - 06:37 AM

Japan hopes to turn sci-fi into reality with elevator to the stars
Leo Lewis in Tokyo

From cyborg housemaids and waterpowered cars to dog translators and rocket boots, Japanese boffins have racked up plenty of near-misses in the quest to turn science fiction into reality.

Now the finest scientific minds of Japan are devoting themselves to cracking the greatest sci-fi vision of all: the space elevator. Man has so far conquered space by painfully and inefficiently blasting himself out of the atmosphere but the 21st century should bring a more leisurely ride to the final frontier.

For chemists, physicists, material scientists, astronauts and dreamers across the globe, the space elevator represents the most tantalising of concepts: cables stronger and lighter than any fibre yet woven, tethered to the ground and disappearing beyond the atmosphere to a satellite docking station in geosynchronous orbit above Earth.

Up and down the 22,000 mile-long (36,000km) cables — or flat ribbons — will run the elevator carriages, themselves requiring huge breakthroughs in engineering to which the biggest Japanese companies and universities have turned their collective attention.

In the carriages, the scientists behind the idea told The Times, could be any number of cargoes. A space elevator could carry people, huge solar-powered generators or even casks of radioactive waste. The point is that breaking free of Earth's gravity will no longer require so much energy — perhaps 100 times less than launching the space shuttle.

"Just like travelling abroad, anyone will be able to ride the elevator into space," Shuichi Ono, chairman of the Japan Space Elevator Association, said.

The vision has inspired scientists around the world and government organisations including Nasa. Several competing space elevator projects are gathering pace as various groups vie to build practical carriages, tethers and the hundreds of other parts required to carry out the plan. There are prizes offered by space elevator-related scientific organisations for breakthroughs and competitions for the best and fastest design of carriage.

First envisioned by the celebrated master of science fiction, Arthur C. Clarke, in his 1979 work The Fountains of Paradise, the concept has all the best qualities of great science fiction: it is bold, it is a leap of imagination and it would change life as we know it.

Unlike the warp drives in Star Trek, or H.G. Wells's The Time Machine, the idea of the space elevator does not mess with the laws of science; it just presents a series of very, very complex engineering problems.

Japan is increasingly confident that its sprawling academic and industrial base can solve those issues, and has even put the astonishingly low price tag of a trillion yen (£5 billion) on building the elevator. Japan is renowned as a global leader in the precision engineering and high-quality material production without which the idea could never be possible.

The biggest obstacle lies in the cables. To extend the elevator to a stationary satellite from the Earth's surface would require twice that length of cable to reach a counterweight, ensuring that the cable maintains its tension.

The cable must be exceptionally light, staggeringly strong and able to withstand all projectiles thrown at it inside and outside the atmosphere. The answer, according to the groups working on designs, will lie in carbon nanotubes - microscopic particles that can be formed into fibres and whose mass production is now a focus of Japan's big textile companies.

According to Yoshio Aoki, a professor of precision machinery engineering at Nihon University and a director of the Japan Space Elevator Association, the cable would need to be about four times stronger than what is currently the strongest carbon nanotube fibre, or about 180 times stronger than steel. Pioneering work on carbon nanotubes in Cambridge has produced a strength improvement of about 100 times over the last five years.

Equally, there is the issue of powering the carriages as they climb into space. "We are thinking of using the technology employed in our bullet trains," Professor Aoki said. "Carbon nanotubes are good conductors of electricity, so we are thinking of having a second cable to provide power all along the route."

Japan is hosting an international conference in November to draw up a timetable for the machine.

Stranger than fiction

"Riding silently into the sky, soon she was 100km high, higher even than the old pioneering rocket planes, the X15s, used to reach. The sky was already all but black above her, with a twinkling of stars right at the zenith, the point to which the ribbon, gold-bright in the sunlight, pointed like an arrow. Looking up that way she could see no sign of structures further up the ribbon, no sign of the counterweight. Nothing but the shining beads of more spiders clambering up this thread to the sky. She suspected she still had not grasped the scale of the elevator, not remotely."

From Firstborn by Arthur C. Clarke and Stephen Baxter
Publisher: Del Ray

Subject: RE: BS: Space Elevator in work
From: Rapparee
Date: 23 Sep 08 - 08:42 AM

I wondered how long it would be before China, India, or Japan built one.

Subject: RE: BS: Space Elevator in work
From: MMario
Date: 23 Sep 08 - 08:49 AM

ONe story I read (and I wonder if it would be feasible) had the DOWNWARD loads providing much of the energy for the UPWARD loads as they generated electricity through generators acting as brakes; gravity powered electrical generation!

Subject: RE: BS: Space Elevator in work
From: Mr Red
Date: 23 Sep 08 - 10:05 AM

And as a target for terrorists? Because they can, that's why.

How do you protect it?

I don't know that Arthur C Clarke was the first to propose it but he certainly championed it and had the Maths to back it up.

Subject: RE: BS: Space Elevator in work
From: Ebbie
Date: 23 Sep 08 - 10:37 AM

Will they need lighthouses to keep away air traffic? :)

Subject: RE: BS: Space Elevator in work
From: katlaughing
Date: 23 Sep 08 - 10:57 AM

I am trying it imagine what this would look like. Would it have some kind of shaft in which the cars would glide up? If so, would that shaft be a solid structure, rising like the tallest skyscraper in the world, vulnerable to the elements, both natural and human? What happens to the lines/cars once they leave our atmosphere or would they? How would they keep them aligned with a space docking unit? Sorry if this seems pedestrian, but I have a vision or elevator cars whipping around at the end of "nanotube lines," tossing around because the orbit of the docking unit has gone out of whack or something. Help me understand how this would work, please? Thanks!

Subject: RE: BS: Space Elevator in work
From: Amos
Date: 23 Sep 08 - 11:13 AM

No shaft, no; the tensioned nano-fiber ribbon would be the tramline to which the cars would cling, like a cablecar; erecting a shaft around it would be too expensive.

Once the thing was in place (a voyage of many many steps) the inertial mass of the space platform would be sufficient to keep it stationary, and presumably the perturbations of loading and traveling the ribbon would be miniscule compared to the tendency to stay stable.

All this would work fine unless and until, as you say, something happened at the platform to suddenly decrease its velocity, such as an accidental retrorocket firing, or a meteorite impact at the wrong angle. Such an event could disrubt all the equations.

Under ordinary conditions, however, the ribbon would be quite stable just as a high earth-orbit satellite is, but with a lot more mass. It would also have the means, I assume, to nudge its velocity up a bit every few years to compensate for the very slight decay factor.


A


A

Subject: RE: BS: Space Elevator in work
From: GUEST,beardedbruce
Date: 23 Sep 08 - 11:19 AM

Basic principle is that the center point is in a stable geosyncronous orbit. Extend the cable up and down ( for balance) until you reach the surface ( and twice the distance out)


Simple enough, if the cable is strong enough. the energy to get into orbit can be recovered when coming back in to the earth ( step off at the center and you are in orbit)

Subject: RE: BS: Space Elevator in work
From: Mr Red
Date: 23 Sep 08 - 12:01 PM

Wind Loading in the jetstream? on a round cable - fairly easy but a flat ribbon? Remember Tacoma.

Subject: RE: BS: Space Elevator in work
From: Amos
Date: 23 Sep 08 - 12:43 PM

An interesting point, Red. I woudl assume a spherical cross-section would be the design of preference, actually.


Anyone who has seen the old black and white films of Galloping Gerty, the Tacomoa Narrows bridge, self-destructing through a positive feedback of resonant frequency oscillations, would probably feel the same.


A

Subject: RE: BS: Space Elevator in work
From: MMario
Date: 23 Sep 08 - 12:52 PM

Kat:

the way it would work is a line (or lines) would stretch from the anchor point on earth up to the point of a geosynchonis orbit and then as far again. At the end a weight would be tethered to keep the line taut. Most proposals include some sort of building/terminal that would enclose the base at the anchor point. They vary in methods above several hundred yards though - some envision a tubular column; some a line or lines emerging from the terminal with the cars riding exposed. Some variations even have the cable traveling THROUGH the cars.

But from the groun it would look tlike the biggest skyscraper you ever saw; vanishing at the upper point.

Subject: RE: BS: Space Elevator in work
From: HuwG
Date: 23 Sep 08 - 01:09 PM

Author Kim Stanley Robinson also envisaged such cables in his "Mars" trilogy. One on earth had to be bifurcated ("Y" shaped) near the base so that one leg was anchored in Trinidad and the other in Tobago.

In "Red Mars", terrorists separate a cable on Mars from its geosynchronous anchor (a captured asteroid named "Clarke"). The falling cable wraps itself two and a half times round the planet. A similar catastrophe on earth would result in a cable falling almost but not quite once round the world.

Subject: RE: BS: Space Elevator in work
From: katlaughing
Date: 23 Sep 08 - 02:32 PM

Thanks, folks. I can just see Jack climbing that beanstalk in the sky, but beanstalks have more substance than a ribbon.:-)

Subject: RE: BS: Space Elevator in work
From: CarolC
Date: 23 Sep 08 - 02:58 PM

I'm imagining what a strong hurricane might do to the cable (I have images of spaghetti in my head).

Subject: RE: BS: Space Elevator in work
From: GUEST,beardedbruce
Date: 23 Sep 08 - 03:02 PM

The Earth end might move around ( which is why we anchor it) but the cenetr of mass is in orbit. MOST of the mass is above the atmosphere, so there will be little effect from weather.( 10 miles out of the 22,000 length)

Might not want to try to get off of it on the Earth end during a hurricane, though.

Subject: RE: BS: Space Elevator in work
From: Rapparee
Date: 23 Sep 08 - 03:17 PM

So put it where there aren't hurricanes. Lots of places inland -- heck, we don't have hurricanes here and a tornado is rare. Or Nevada, or Utah, or New Mexico, or Alberta, or Manitoba, or...you get my point.

Subject: RE: BS: Space Elevator in work
From: beardedbruce
Date: 23 Sep 08 - 03:22 PM

it HAS to be on the equator.

Subject: RE: BS: Space Elevator in work
From: Don Firth
Date: 23 Sep 08 - 06:33 PM

A filament under tension! And that long! If one were to pluck it, would one be even able to hear what note it played?

(I can get curious about the damndest things. . . .)

Don Firth

Subject: RE: BS: Space Elevator in work
From: MMario
Date: 23 Sep 08 - 06:43 PM

The maths allow a little leeway; but not much.

Subject: RE: BS: Space Elevator in work
From: Rapparee
Date: 23 Sep 08 - 09:06 PM

Ecuador, Johannesburg...still lots of choices.

Subject: RE: BS: Space Elevator in work
From: The Fooles Troupe
Date: 23 Sep 08 - 09:42 PM

"If one were to pluck it, would one be even able to hear what note it played?"

Hmmmm, subsonic... earthquake starters?

:-) Damn your curiousity, Don!

Subject: RE: BS: Space Elevator in work
From: CarolC
Date: 23 Sep 08 - 10:08 PM

It would make a hell of a wind harp, I guess. Might even drive people nuts if they put it in a populated area.

Subject: RE: BS: Space Elevator in work
From: The Fooles Troupe
Date: 24 Sep 08 - 02:10 AM

Hmmm, Frequency varies as inverse of length...

22,000 miles....

Subject: RE: BS: Space Elevator in work
From: beardedbruce
Date: 24 Sep 08 - 06:33 AM

The anchor is a single point at the center. The ends are NOT significant support points (though for ease of use the earth end shoud be attached to the earth.)

Wind would make little difference ( see earlier- most mass is out of the atmosphere)

Rapaire- Johannesburg??? Look at an atlas, please. ON the equator.

Subject: RE: BS: Space Elevator in work
From: Mr Red
Date: 24 Sep 08 - 07:49 AM

Hmmm, Frequency varies as inverse of length... where is the car?
= bridging point. Put a significant mass on a guitar string and tell me what note you get.

Ignoring harmonics - I would bet there are several. The base note as the mass moves (though it's mass would alter it a bit), the one based on the free length above, and one based on the note below. I think we would have a glissando too as the car moves.

And then there are the sum and difference harmonics (beat frequencies) because the system is probably non-linear. And then all the harmonics of all frequencies mentioned and beat frequencies of therof.

Buildings make noises in high wind and not that pleasant sometimes. A road sign near me has no top to the pole (a tube) - and that moans in the wind. Same principle.

Subject: RE: BS: Space Elevator in work
From: The Fooles Troupe
Date: 24 Sep 08 - 08:41 AM

"base note (fundamental) as the mass moves"

Just like sliding a glass bottle neck along a string...

"Ignoring harmonics - I would bet there are several. The base note as the mass moves (though it's mass would alter it a bit), the one based on the free length above, and one based on the note below. I think we would have a glissando too as the car moves.

And then there are the sum and difference harmonics (beat frequencies) because the system is probably non-linear. And then all the harmonics of all frequencies mentioned and beat frequencies of therof."


Hmmm, Mr Glass would be delighted...

Subject: RE: BS: Space Elevator in work
From: Donuel
Date: 24 Sep 08 - 08:44 AM

The longest nano fiber made is about 1cm long. That makes braided a 22,000 miles km long problomatic.

more than just an elevator it would conduct electricity to the ground like a sum bitch.

Subject: RE: BS: Space Elevator in work
From: Donuel
Date: 24 Sep 08 - 08:46 AM

btw
the Hadron collider is down for repairs until next year...


oops

somethin happened.

Subject: RE: BS: Space Elevator in work
From: The Fooles Troupe
Date: 24 Sep 08 - 08:58 AM

The helium leaked, Donuel.

Subject: RE: BS: Space Elevator in work
From: The Fooles Troupe
Date: 24 Sep 08 - 09:07 AM

Sorry, blew that... the cooling circuit leaked...

Subject: RE: BS: Space Elevator in work
From: The Fooles Troupe
Date: 24 Sep 08 - 09:32 AM

Japan plans world's first space elevator

Pics too!

Subject: RE: BS: Space Elevator in work
From: Donuel
Date: 24 Sep 08 - 11:16 AM

Helium Leak?

A conversation in the Hadron might sound like Mickey Mice.

Subject: RE: BS: Space Elevator in work
From: MMario
Date: 24 Sep 08 - 11:39 AM

hey bruce - I thought current designs had a counterweight mass at the far end (at twice geosynch distance)?

Subject: RE: BS: Space Elevator in work
From: gnu
Date: 24 Sep 08 - 02:08 PM

Spider silk? But, how do you climb it? Use a lot of itsy bitsy spiders?

Subject: RE: BS: Space Elevator in work
From: GUEST,beardedbruce
Date: 24 Sep 08 - 04:05 PM

counterweight, but not anchor. Think of a board supported in the middle- you want both sides to be the same for balance, even if the onlt anchor is the center.

Subject: RE: BS: Space Elevator in work
From: GUEST,Slag
Date: 24 Sep 08 - 05:07 PM

Don!   "OMMMMMM"

Cars that can release in an emergency at atmospheric elevations and glide to a safe landing. It might even serve as a launch point for cargo and passenger transport.

Other than the above mentioned cars/gliders an aero defense no-fly zone of say 500 mile radius protected by energy weapons (lasers, etc.)

Tether point would have to have redundant attitude adjustment capabilty. Didn't Clarke suggest marshalling an asteroid into the geo-sync position?

Lot'sa opprotunity here. Unite Mankind, eventual total population control and monitoring. Exploit "heavenly" resources. I suggest we call it "Babel".

Subject: RE: BS: Space Elevator in work
From: Rapparee
Date: 24 Sep 08 - 08:52 PM

Exploit the L-5 positions.

Subject: RE: BS: Space Elevator in work
From: Rapparee
Date: 24 Sep 08 - 08:54 PM

By the way, why wouldn't a South Pole anchor work? (Yeah, yeah, I know about the winds and stuff.) A North Pole anchor could be a deep sea platform -- and for that matter, why does the terrestrial anchor point have to be on dry land?

Subject: RE: BS: Space Elevator in work
From: The Fooles Troupe
Date: 24 Sep 08 - 09:16 PM

"Exploit the L-5 positions."

Rapaire, I can't find those in my copy of the Kama Sutra...

Subject: RE: BS: Space Elevator in work
From: cptsnapper
Date: 25 Sep 08 - 01:55 AM

Somehow, and I don't know why, Noel Murphy's " The Bricklayer's Song " - a musical version of a story recounted by Gerard Hoffnung at the Oxford Union explaining why a man can't go to work- comes to mind!!

Subject: RE: BS: Space Elevator in work
From: GUEST,BanjoRay
Date: 25 Sep 08 - 07:07 AM

A South or North Pole achor wouldn't work because you need the centrifugal force at the equator to keep the cable in tension. That's a thought - how much weight do you put on by moving from the equator to one of the Poles (apart from your backpack, that is)?
Ray

Subject: RE: BS: Space Elevator in work
From: beardedbruce
Date: 25 Sep 08 - 09:31 AM

Rapaire,

Geosynchronous orbits are at or arount a point on the equator. Since we want the anchor point to be stationary, it MUST be in an equatorial orbit. Simple astrodynamics.

An orbit over the pole would be the opposite- it would sweep over the Earth ( as the earth turned) and you could never have a stationary point.

Subject: RE: BS: Space Elevator in work
From: The Fooles Troupe
Date: 25 Sep 08 - 10:06 AM

"as the earth turns"

I don't watch TV soaps...

Subject: RE: BS: Space Elevator in work
From: beardedbruce
Date: 25 Sep 08 - 10:51 AM

Or notice the sun "rise" today, either, I guess...

Subject: RE: BS: Space Elevator in work
From: The Fooles Troupe
Date: 25 Sep 08 - 07:35 PM

The sun does not rise, the earth sucks sinks.

Subject: RE: BS: Space Elevator in work
From: GUEST,Slag
Date: 25 Sep 08 - 08:04 PM

The Sun also rises, but that's just so much steerage.

Subject: RE: BS: Space Elevator in work
From: Grab
Date: 26 Sep 08 - 01:02 PM

HuwG, Robinson certainly included a nice disaster scenario in his book. Like most epic disaster fiction though, it makes good fiction but bad fact. Unless there's a force pushing it sideways, what gets dropped falls straight down. You wouldn't want to be within a few miles of the base, but that's all.

As I remember, the idea isn't that we anchor the Earth end, but that we give it the freedom to move around a bit in response to whatever atmospheric wiggles go on. The fixed point has to be the satellite end (where there's a stonking big bit of rock or something as a counterweight), not the Earth end. So putting the Earth end out at sea solves the problem by letting it float around as needed.

NASA has at least two separate projects going for this. One is working on the problem of how to make the cable, and the other is figuring out how to make something climb the cable.

Graham.

Subject: RE: BS: Space Elevator in work
From: GUEST,beardedbruce
Date: 26 Sep 08 - 01:04 PM

"The fixed point has to be the satellite end (where there's a stonking big bit of rock or something as a counterweight), not the Earth end"

Actually, the CENTER point ( in geosynchronous orbit) is the anchor- the ends are NOT support points.

Subject: RE: BS: Space Elevator in work
From: MMario
Date: 26 Sep 08 - 02:09 PM

okay - yup I get the difference between anchor and counterweight now.

Somewhere I once saw the maths that explain in what cases the "eleavator" would drop

a) nearly straight down

b) wrap around the earth

c) fly our to space

or in some cases a & C or b & C
to varying degrees.

but I don't recall. It primarily had to do with vector forces acting on the cable and where along the length problems occurred etc.

Subject: RE: BS: Space Elevator in work
From: GUEST,beardedbruce
Date: 26 Sep 08 - 02:36 PM

"where along the length "

exactly- think of a rope whose CENTER is in orbit over a specific spot on the Earth- ( Dragging the two ends along, since they are balanced against each other)

If there is a break, it will change the balance ( center of mass)

the new center of mass will be either above or below geosync, leading to either

1. a closed conic section intersecting the Earth
2. an open conic section taht flies off into space

The CM at geosync gives the desired solution of an orbit around the Earth that does not intersect the surface ( at least, the CM does not.)

As stated before, drag is small (on 10 - 100 miles, out of 22,000) so can be ignored for the first order solution.


But not a great idea to build high drag structures on the lower ( high atmospheric density) section- that first 10 miles.

Subject: RE: BS: Space Elevator in work
From: HuwG
Date: 29 Sep 08 - 01:51 AM

I've been re-reading Kim Stanley Robinson's "Red Mars". Robinson's cable was ten meters in diameter. It weighed six billion tons. Its anchor point in orbit was an asteroid named "Clarke", which weighed seven and a half billion tons.

Clarke would have been outside the asynchronous orbital altitude of 17,049 Km, measured from the surface. My calculator bashing suggests that Clarke is very roughly 2944 Km beyond the asynchronous orbit, at an altitude of 19,993 Km.

The system can be treated as a single mechanical unit with its centre of gravity at the asynchronous altitude.

When the terrorists pulled the cable out of Clarke, the cable suddendly became a separate unit with a cen

Subject: RE: BS: Space Elevator in work
From: HuwG
Date: 29 Sep 08 - 02:05 AM

Ack! Damn' submit button!

To continue, the cable suddenly becomes a separate unit, with its centre of gravity 9,900 Km above the surface. I'll have to sleep on this, to work out how conservation of energy affects matters, but I suspect the cable will immediately acquire apparent horizontal velocity in the direction of the planet's rotation i.e. the cable will appear to fall forwards, rather than be dragged around by the planet. Once this forward motion is acquired, it will be combined with the downward acceleration due to gravity to indeed wrap the planet.

I suspect that even if I am wrong, the cable will have sufficient rigidy to prevent it simply falling vertically and creating a pan-scrubber which would undoubtedly make the "Guiness Book of Records".

Subject: RE: BS: Space Elevator in work
From: beardedbruce
Date: 29 Sep 08 - 07:21 AM

A significant point not yet discussed:

IF the upper end point is used as a s/c launch point, the object falling off of it will have a velocity in excess of the orbbital velocity at that distance- ie, it will get a boost towards whatever destination it has, as soon as it separates from the "elevator"


Not a bad investment- both access to orbit and a launch capability to the rest of the solar system.

Subject: RE: BS: Space Elevator in work
From: GUEST,beardedbruce
Date: 03 Oct 08 - 11:54 AM

updated 1 hour, 37 minutes ago

   'Space elevator' would take humans into orbit

Story Highlights
Japan group has more than 100 engineers trying to design a space elevator

Carbon nanotube would be used as a wire to lift the elevator into space

Western Australia and the Galapagos Islands are potential locations for base station

Group sets the 2030s as a target to begin construction, although it could be later

By Mike Steere
For CNN

   
LONDON, England (CNN) -- A new space race is officially underway, and this one should have the sci-fi geeks salivating.

The project is a "space elevator," and some experts now believe the concept is well within the bounds of possibility -- maybe even within our lifetimes.

A conference discussing developments in space elevator concepts is being held in Japan in November, and hundreds of engineers and scientists from Asia, Europe and the Americas are working to design the only lift that will take you directly to the one hundred-thousandth floor.

Despite these developments, you could be excused for thinking it all sounds a little far-fetched.

Indeed, if successfully built, the space elevator would be an unprecedented feat of human engineering.

A cable anchored to the Earth's surface, reaching tens of thousands of kilometers into space balanced with a counterweight attached at the other end is the basic design for the elevator.

It is thought that inertia -- the physics theory stating that matter retains its velocity along a straight line so long as it is not acted upon by an external force -- will cause the cable to stay stretched taut, allowing the elevator to sit in geostationary orbit.

The cable would extend into the sky, eventually reaching a satellite docking station orbiting in space.

Engineers hope the elevator will transport people and objects into space, and there have even been suggestions that it could be used to dispose of nuclear waste. Another proposed idea is to use the elevator to place solar panels in space to provide power for homes on Earth.

If it sounds like the stuff of fiction, maybe that's because it once was.

In 1979, Arthur C. Clarke's novel "The Fountains of Paradise" first brought the idea of a space elevator to a mass audience. Charles Sheffield's "The Web Between the Worlds" also featured the building of a space elevator.

But, jump out of the storybooks, fast-forward nearly three decades and Japanese scientists at the Japan Space Elevator Association (JSEA) are working seriously on the space-elevator project.

JSEA spokesman Akira Tsuchida told CNN his organization was working with U.S.-based Spaceward Foundation and a European organization based in Luxembourg, to develop an elevator design.

The Liftport Group in the U.S. is also working on developing a design, and in total it's believed over 300 scientists and engineers are engaged in such work around the globe.

NASA is also holding a $4 million Space Elevator Challenge to encourage designs for a space elevator than can work.

Tsuchida said the technology driving the race to build the first space elevator is the quickly developing material carbon nanotube. It is lightweight and has a tensile strength 180 times stronger than steel cable. Currently, it is the only material with the potential to be strong enough to use to manufacture elevator cable, according to Tsuchida.

"At present we have a tether which is made of carbon nanotube, and has one third or one quarter of the strength required to make a space elevator. We expect that we will have strong enough cable in the 2020s or 2030s," Tsuchida said.

He said the most likely method of powering the elevator would be through the carbon nanotube cable.

So, what are the major logistical issues keeping the space elevator from being anything more than a dream at present?

Massachusetts Institute of Technology (MIT) Aeronautics and Astronautics Professor, Jeff Hoffman, said designing the carbon nanotube appeared to be the biggest obstacle.

"We are now on the verge of having material that has the strength to span the 30,000 km ... but we don't have the ability to make long cable out of the carbon nanotubes at the moment." he said. "Although I'm confident that within a reasonable amount of time we will be able to do this."

Tsuchida said one of the biggest challenges will be acquiring funding to move the projects forward. At present there is no financial backing for the space elevator project and all of JSEA's 100-plus members maintain other jobs to earn a living.

"Because we don't have a material which has enough strength to construct space elevator yet, it is difficult to change people's mind so they believe that it can be real," he said.

Hoffman feels international dialogue needs to be encouaraged on the issue. He said a number of legal considerations also would have to be taken into account.

"This is not something one nation or one company can do. There needs to be a worldwide approach," he said.

Other difficulties for space-elevator projects include how to build the base for the elevator, how to design it, and where to set up the operation.

Tsuchida said some possible locations for an elevator include the South China Sea, western Australia, and the Galapagos Islands in the Pacific Ocean. He said all of those locations usually avoided typhoons, which could pose a threat to the safety of an elevator.

"As the base of space elevator will be located on geosynchronous orbit, [the] space elevator ground station should be located near the Equator," he said.

While JSEA has set a time frame of the 2030s to get a space elevator under construction -- and developments are moving quickly -- Hoffman acknowledges it could be a little further away than that.

"I don't know if it's going to be in our lifetime or if it's 100 or 200 years away, but it's near enough that we can contemplate how it will work."

Building a space elevator is a matter of when, not if, said Hoffman, who believes it will herald a major new period in human history.

"It will be revolutionary for human technology, and not just for space travel. That's why so many people are pursuing it," he said. "This is what it will take to turn humans into a space-bearing species."

Subject: RE: BS: Space Elevator in work
From: NightWing
Date: 03 Oct 08 - 10:03 PM

HuwG said, "One [space elevator] on earth had to be bifurcated ('Y' shaped) near the base so that one leg was anchored in Trinidad and the other in Tobago."

Trinidad & Tobago are on a single island, about 80 km across, located about (VERY!!! roughly) 5° (five degrees) north of the equator. If the ends of a bifurcated space elevator were located both in--more or less--the same place like that they would act as a single end ... 5° OFF the equator. As it orbited it would swing through a curve from 5° north to 5° south on a 24-hour cycle. Hard to get on or off an elevator that's moving about 25 km/hr (on average).

Instead Robinson's bifurcated space telescope had one end in T&T and the other that far SOUTH of the equator. La Paz (in Bolivia), Cuiabá, or Brasilia (both in Brazil) are three possible choices. (I don't remember where Robinson had his, although I just read the trilogy a couple months ago.)

BB,
NightWing

Subject: RE: BS: Space Elevator in work
From: GUEST,beardedbruce
Date: 07 Oct 08 - 07:09 AM

refresh

Subject: RE: BS: Space Elevator in work
From: Zen
Date: 07 Oct 08 - 09:19 AM

Whilst it might be theoretically possible to design such a tethered structure, in practice no materials currently exist with the necessary tensile strength... even carbon nanotubes would fall somewhat short of what would be required. If a way could be found to produce the current favoured candidate material, carbon nanotube fibres (ideally single-walled from a mass point of view) in sufficient quantities and with sufficient lengths to be woven, braided and bound into a tether with the required mechanical characteristics there could still be potential problems such as the likely electrical conductivity of such a cable.

I'm not dismissing the idea per se but the quoted Japanese target of 2030 would seem a little optimistic given current technology.

Subject: RE: BS: Space Elevator in work
From: McGrath of Harlow
Date: 07 Oct 08 - 05:52 PM

Trinidad & Tobago are on a single island,

No they aren't. Here's a map, courtesy of the CIA. (I know the CIA don't always get things right, but this time they did.)

Subject: RE: BS: Space Elevator in work
From: gnu
Date: 01 Jan 11 - 06:06 PM

Pie in the sky?


Sorry if this was posted previously.

Subject: RE: BS: Space Elevator in work
From: Slag
Date: 02 Jan 11 - 03:36 AM

The "Crawlers" or elevator cars would have the capability to micro examine and do repairs to the cables. The cable itself might act as an electrostatic inducer and supply some or all the current necessary to operate the powerful engines required to move massive loads up and down or, more correctly, in and out of Earth's gravity well. An absolute "no-fly" zone of a thousand miles radius might be established to repel crazies from assaulting the machine. Similar restrictions on all water borne vessels. Space junk and meteoroids would be an ever constant source of danger as the cables are completely immovable but here, stand-off sheilding could be employed and maintained as are low-orbit satellites. Vessels docking and undocking with the counter weight ( a small metalic asteroid perhaps ) would also present engineering problems and, potentially, a great hazzard, should an accident occur. The escapablility of the crawlers, especially smaller ones for living passngers only, is easily handled. Cargo only crawlers would need the 1000 mile buffer zone to avoid immediate damage to Earth, other than the anchor points. Twenty thousand and some odd miles of sharp and ridgid nano-carbon cables would present an enormous hazzard to Earth dwellers. It would fall at super-sonic speeds and slice through most materials it encountered.

If we Earthlings had the ability to do this project it should first be attempted on the Moon where unforseen problems would not endanger Earth's inhabitants. The prototype would be beneficial to Lunar enterprizes in much the same way a space elevator would directly benefit Earth. Regardless we need an established permanent presence in the Earth Moon system to even begin and maintain the industries needed to accomplish such a grand endeavor.

Subject: RE: BS: Space Elevator in work
From: GUEST,Shimrod
Date: 02 Jan 11 - 09:35 AM

"Twenty thousand and some odd miles of sharp and ridgid nano-carbon cables would present an enormous hazzard to Earth dwellers. It would fall at super-sonic speeds and slice through most materials it encountered."

Yep! I once saw a few tons of scaffolding collapse from a 4 or 5 storie building. The energy released by this event was amazing with 18 ft scaffolding poles tied into knots! The effect of a collapsing space elevator doesn't bear thinking about.