Highlift Systems' Space Elevator In The News Again

Kris_J writes "Highlift Systems may have found a second location for the anchor of their space elevator -- Perth, Western Australia. Apparently we have the calm waters and international airport that it needs, amongst other things. Slashdot has covered this company's efforts before: Oct 9, 2002 and, earlier, August 13, 2002, but it's worth discussing again since '[recent funding] has been given momentum by the Columbia shuttle disaster.'"

Comments

Question

[KeatonMill]

This is probably a stupid question, but why wouldn't inertia rip it apart? The way I see it happening is as follows: The bottom of the elevator is firmly anchored to Earth and the top is floating in space. The bottom is anchored so its movements match Earth's. The top, however, is so high up that it lags behind a bit and bends the whole elevator. Eventually, the material weakens and bends enough that the Earth pulls it down gravitationally and breaks it in two.

Also, could this possible create drag in the solar wind and slow the Earth's rotation? (most likely another stupid question)

Re:Question

[Anonymous Coward]

> Also, could this possible create drag in the
> solar wind and slow the Earth's rotation?

No, however there is an effect that will slow down the earth. Moving things from the surface to orbit increases their angular momentum, which in turn decreases the angular momentum of the earth. The effect is negligably small though and explained in the FAQ on the company home page i believe...

Re:Okay

[silvaran]

What is bearing the load against the earth's gravity?

Rotational velocity. The rotation of the earth imposes an outward force on the elevator, keeping it in place. The elevator would be anchored to the earth, not anchored to the sky.

you slack or stupid?

[QuantumG]

Simply read the docs:

The simplest explanation of the space elevator is that it is a cable with one end attached to the Earth's surface and the other end in space beyond the geosynchronous orbit (35,800 km altitude). The competing forces of gravity at the lower end and outward centrifugal acceleration at the farther end keep the cable under tension and stationary over a single position on Earth. This cable, once deployed, can be ascended by mechanical means to Earth orbit.

Which just goes to show, if you're asking on Slashdot, then you're either too lazy or too stupid to find out yourself.

Re:Okay

[Anonymous Coward]

So does that (geosynchrony) mean you can only install such an elevator near the equator? Is Perth just the most likely "close enough" site?

Am I gonnahafta RTFA?

Why Bother?

[Farley Mullet]

If you ask me, we put altogether too much emphasis on putting stuff in orbit these days. Manned space exploration has been stalled since the end of the Apollo program; putting people into orbit has become the be-all and end-all. Our focus should be beyond orbit; we should head back to the moon, and then on to Mars. Right now, we are doing fine using disposable rockets to put satellites into orbit, and assuming that the investigation into the Columbia disaster comes up with substantive results and recommendations, the shuttle program can continue to put people into orbit (and we end up grounding the shuttles, I don't see why we can't use Soyuz-like capsules to send people to orbit). If we're planning new space technologies (and major space-related capital commitments) I think we must literally aim higher than Earth orbit. While a space elevator would be an incredible technical achievement, it should wait until we have enough in the way of manned orbital stations to justify the cost, or until private companies want to pay for it as a satellite delivery system.

If we're going to spend that much money on space, we should spend it on space exploration.

Re:Why Bother?

[Dyolf Knip]

Firstly, manned missions have been stalled because it costs $10,000 to $20,000 to put a single pound in orbit and people require an awful lot of support to go with them. Secondly, LEO is indeed the starting point for getting anywhere else. The Apollo approach of sending up the entire voyage from the ground and back in one module will never work for anything bigger. You have to send up parts and assemble them in space. Thirdly, pure exploration we can mostly do with automated probes. It's nice and informative, but not our goal, which is getting large populations of human beings off this rock. Be it colonizing other planets, space habitats, mining asteroids and comets, or whatever.

Re:Why Bother?

[gilroy]

Blockquoth the poster:

putting people into orbit has become the be-all and end-all. Our focus should be beyond orbit; we should head back to the moon, and then on to Mars.

Don't take this as flamebait, but this sort of thinking is exactly why things have stalled: A penchant for the flashy combined with essentially no understanding of what's actually involved in space exploration, nor of what's needed.

If you want to settle the Moon or explore Mars or any other grandiose thing, you're going to absolutely need cheap Earth-to-orbit capability. Right now it's about $10,000 per pound that we lift -- that means almost nothing can be profitably put into orbit. Bring that down, and the rest follows.

To stretch a historical analogy, while exploration of North America occured since 1500, massive settlement of it awaited the railroads and cheap transport. (And put down those flamethrowers ... I am not trying to discount the Native American presence in North America. Of course, without railroads, that took literally thousands of years. With railroads, that population was exceeded in about 100 years.)

Doesn�t the anchor need to be on the equator?

[RNLockwood]

I thought that the anchor needed to be on the equator and Perth is aoubt 36 degrees south. I would imagine that there would be really large lateral forces on the anchor and suspect that the cable would be curved.

Re:Australia?

[Mantorp]

one of the requirements: "In or near an economically advanced and politically stable country."
Though they may be good at cricket, I wouldn't call Sri Lanka politically stable.

Re:Okay

[JWSmythe]

It's the same force that keeps the moon in orbit without falling down on us..

Centrifugal force pulls the moon away from us.

Gravity (both from the Earth and Moon) pull them towards each other.

Kind of like if you swing a weight on a string. But gravity is the string. That's why the moon can be not in a geosynchronous orbit. It's string moves. :)

With a heavy weight (platform) on the end of their carbon nanotube string, far enough away from the Earth, the platform should be pulling on the string, so the fact that you're pulling a bit on the string back down isn't much.. You'd be as significant as an ant on top of a mountain. :)

That'll be an interesting place to visit..

I wonder how long after the build it, that someone will build a solar sail craft.. It's not a hard concept.. Make "sails" big enough to create a small force from the solar winds. Then it would be a simple matter of riding the winds and gravational forces of the bodies encountered. Mars may be a lot closer than we thought.. You could fly the solar system with almost no fuel. :)

I volunteer to take a fast run to Pluto. The course should be pretty easy. It'll just take a little math to figure out..

Leave the platform, "falling" towards the moon. Pass the moon, and change your vector towards the sun (ok, a little fuel). Now "fall" towards the sun.. It's a good sized object, it should have a little pull. (hehe).

Use Venus and it's moons your next turning point. Sails out, then pick and choose your planets to use to manuver..

With a bit of good navigation other solar systems aren't quite as unreachable as they are now..

Re:But Why on the Ocean?

[HeghmoH]

Mr. Robinson's vision does not match up with the modern concept of a space elevator. The proposed elevator would be extremely small and thin, as in paper-thin, and would have a very, very low mass/length ratio. Also, it would not be much stronger than required to hold it together in normal orbit. All this means that if it broke near its anchor, it would fracture into lots of small pieces which would then all burn up harmlessly in the atmosphere as they reentered.

The Mars Trilogy's elevator is on a smaller planet with much less atmosphere, and it's apparently also ridiculously over-engineered. (Or maybe it was built with more commonplace materials, instead of carbon nanotubes as is being explored today... anybody who's read the books more recently than I have care to comment?)

In short, don't worry about cable breaks, unless you're on the cable at the time, or you have stock in the elevator company.

Re:Okay

[WolfWithoutAClause]

It's self stabilising. If the cable goes slightly off the vertical, the rotation ('centrifugal force' if you like fictious forces) tends to pull the cable back above the fixing point; it's like a giant pendulum.

Re:Okay

[Anonvmous Coward]

"Seriously, don't you think they would have considered things like that before heavily funding this space elevator?"

Seriously, don't you think that's why I asked instead of declaring they shouldn't use it? Any reason you didn't just answer my question instead of weakly attempting to insult my intelligence?

Re:which end first?

[Anonymous Coward]

In terms of energy expenditure, it doesn't really matter, since either way, you have the same amount of stuff going up. However, I think it's be easier (relatively) to get the whole ribbon up into geosynchronous orbit first, and then unroll it both ways simultaneously.

when i think of a space hook i think of

[kraksmoka]

the heinlen novel "Friday" which describes a system with space elevators that go to the lagrangian points. worth a read any way you cut it though.

Re:It seems like..

[debrain]

War need not imply innovation. A war with Iraq et al. won't encourage new technology. It may be used to excuse past expenses in otherwise unjustifiable research, though.

WRT the anecdotal comment regarding mining diamonds: Potential diamond yield is unlikely to encourage anything, since diamond production is artificially stymied by a cartel. I'm pretty sure you didn't mean it seriously, but it does elucidate the enigma of incentive, which is really the core of this converse.

I think your comments on a China space race, and allusion to Nazi induced innovation, are right on the money. Let us hope that, with respect to the latter, it is not a price we should have to ever again pay for innovation.

not quite orbiting

[Anonymous Coward]

at the equator, the ribbon extends vertically from its anchor.

as the anchor is moved towards the axis of rotation (south pole) the ribbon begins to extend horizontally from its anchor, but it still approximately parallel to the equatorial ribbon.
the counterweight will settle just south (or north) of the equator due to the south-pulling force from the anchor. no oscillation.

Just the opposite

[roystgnr]

This is why most designs count on the bottom of the elevator touching the ground, so that a significant portion of the elevator's weight can be supported by contact with the earth instead of tension in the elevator.

First of all, the tendency to buckle makes it vastly more difficult to build a long structure under compression than one under tension. Building a structure to support the elevator from below would be just like building any other skyscraper; you wouldn't get the top of the section under compression to be more than a mile off the ground, and after that you'd still have 25,000 miles to go.

But perhaps just as importantly, the bottom of a geosynchronous elevator design needs to touch the ground because it needs the base to be pulling down on it, not lifting up. If you want to take a 20 ton payload up the elevator without pulling it down, then the elevator is going to need to be under at least 20 tons of tension at the ground when there is no payload on it.

Re:Just the opposite

[MillionthMonkey]

But perhaps just as importantly, the bottom of a geosynchronous elevator design needs to touch the ground because it needs the base to be pulling down on it, not lifting up. If you want to take a 20 ton payload up the elevator without pulling it down, then the elevator is going to need to be under at least 20 tons of tension at the ground when there is no payload on it.

Naah, not necessarily.

Say (for simplicity of argument) we have a free-floating design, with a basket hanging a few feet off the ground. In equilibrium, the center of mass of the entire elevator (basket, cable, counterweight) is in geosynchronous orbit.

You put a 20 ton payload into the basket. This shifts the CM downward by an amount. So you pump (weightless) hydrazine up the elevator to corrective rockets sitting on the counterweight, and the rockets push the CM back up into geosynchrous orbit. They do this by pushing the counterweight into a realm above geosync orbit where it experiences a centrifugal force of 20 tons in the upward direction, and this equilibrates with the 20 tons pulling down on the ground. Of course the centrifugal force isn't a "real" force, it's really just an artifact of inertial effects within a rotating coordinate system.

Once the CM is in stable orbit again it doesn't matter what you do with forces internal to the orbiting assembly, i.e. between the counterweight and the basket. Pulling the basket up to the level of the counterweight won't alter the CM placement. (Although sideways Coriolis forces on the rising 20 tons will start complicating things on the way up.) Still, the amount of rocket fuel spent raising the payload into orbit this way is much less than with a conventional rocket.

Your design is slightly different in that you have the CM sitting outside geosynchronous orbit in the realm where it experiences the outward centrifugal force all the time. So you've got the other end attached to the ground, pulling up on it. This is conceptually a little bit simpler to grasp, but it puts increased tension in the cable, and after lifting a certain amount of stuff into orbit, the CM of the system will reach geosynchronous orbit anyway- and all the tension at the ground will be gone.

You angle the sail, and/or you tack.

[leonbrooks]

People in canoes have been doing this for thousands of years already. It's actually possible to accelerate towards a star, on average.

Lack of Imagination?

[mamahuhu]

I'm appalled at the lack of imagination shown by most of these posts.

First off if you read the PDF (15M) report to Nasa prepared by Bradley C. Edwards to satisfy the requirements of his $500 000 grant you will readily see that this is totally feasible.

Next check out the website - where they are calling for people to express interest in working on this project. They expect to be hiring in the next year or so. You'll also see that serious people are taking this seriously. Do you want a job?

Next understand that $17B is not very much money. Considering that BP just spent $6.7B on a oil company in Russia and has plans for more purchases.

I meantion BP because they have a plan to move beyond oil.... BP Solar is BP's attempt to become a broader energy company (check out their new sun logo) instead of an oil company. The High Lift systems news page says: -

BP Solar - a subsidiary of British Petroleum, currently doing $300M in annual sales. Our discussions have focused on BP's interest in using the SE for deployment of a solar energy satellite. Several items that came up included possible collaborative efforts, the performance of our system and the possibility of BP using our system. They are considering writing a letter of endorsement

If BP with the cash they have can throw $6.75 B at Russia they could, over 5 years, finance a large share of the Space Elevator. Who needs the Government? In fact Nasa would make sure it costs more to build than it should. Nasa is a bureaucracy, not a business, and is ill-suited to the sort of cost control required of economically viable business decision. Only communists would argue that a Space Elevator should be built and controlled by government.

What would BP Solar do? Build Power Sats....

These are High Lift's vision for the main use for the Space Elevator. Imagine a fleet of these beaming power to anywhere on earth. Every country on the planet could get cheap electricity without the huge national grid infrastructure required now. Without the huge investments in time and resources to build power stations - and without the fossil fuel use.

Use your imagination.

These ideas have been the subject of SF for decades - but the Space Elevator is now possible due to those nifty Carbon Nano-tubes.

When your imagination focussed by the reality of this thing actually being built in the near term (5 years) everything changes - and it'll change for us not our children. It'll change our careers.

Imagine this - an electric airplane that is powered by a Powersat beaming microwaves to it. No fuel to carry, super efficient travel - and at what speeds?

These guys are planning for the Space Elevator to be operational SOON - they have realistic timelines.

What I want to see here is some discussion of the uses that could realistically be made of a space elevator. We're the generation that will built it, use it and be changed by it. I like the parallel to be made with electricity, or flight, or the steam engine - in the early stages everyone probably dismissed it - and the world changed despite them.

What would you realistically (with a nod towards economic viability) do with the low launch costs they're projecting - $10/LB...

Ideas anyone?

Re:Terrorist Target?

[TheMidget]

An interesting thing I read in a paper on this subject, was that after a year or so of strengthening the cable, you could lift a second ribbon for another space elevator, etc....

This would significantly reduce the appeal for attack that a single space elevator would have.

That assumes that the only reason why the terrorists would attack the ribbon would be to disrupt its operation. However, in reality, terrorists would attack the ribbon for its potential to wreak havoc. If a terrorist blows up a dam, he doesn't do it to deprive nearby cities of drinking water or electricity. He does it to provoke a flooding catastrophe!

Although Highlift's website downplays the effects of a ribbon rupture, somehow I've trouble believing them. If the cable is strong enough to hold up, wouldn't it also be strong enough to slice everything in half that it encounters on its way down? As anybody having worked on a ship can attest, a rope under tension packs a helluva lot of destructive energy, which is released all at once when it snaps. It'll certainly do much more damage than "loose sheets of newspapers".