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.