Moon Elevator?

I think the cable would weigh to much...and it might pull the moon closer.

Yes

No

Good answer...in that it recognizes an inherent flaw (of reasoning) in the original question - Positing a theoretical (physics) question regarding the possiblity of a space elevator - but coupling it with an "applied physics question...viz: essentially about what would make the theoretical question invalid OR(!) valid? Guests has answered that component of the inquiry which is not fallacious in and of itself.

As to space elevator (or moon... under the right [non-earth] conditions), that was discussed previously on CR4, but was not recognized for what it was!

That mass that were raised from the surface of the earth would need to be supplied with energy to keep it there. If it doesn't come from the geosync satellite losing altitude, and changing its speed, during the hoisting operation, where does it come from (rhetorical question)?

It's easier to get rid of the clothes line and accelerate the mass using some form of vehicle. Which is sort-of-why it is done that way.

It is possible, not quite technologically feasible yet. I remember reading a story about this several years ago one of the problems is any currently available material would break under its own weight much less putting any load on. Carbon nano tubes show promise as a material that would be strong enough to create such a cable.

http://en.wikipedia.org/wiki/Space_elevator

See also http://www.npl.washington.edu/AV/altvw109.html

Any cable long enough would weigh quite a bit I would think. We would first need to blast the whole thing up into orbit before we could "drop" it to earth. Not sure we have the ability to send that type of payload to orbit. If we were to do it in sections, it would be a complicated ordeal to hook the different pieces together while hanging in semi-orbit. Personally I think we need to put more efforts into either the time machine, or the molecular transporter.

I remember reading somewhere, years and years ago, that there is nothing man made that will support it's own weight up to 1 mile. Spider silk was the only thing that had the properties that might have worked but we could not duplicate it nor get the little buggers to weave it into a cable.

Are you referring to a standing structure one mile high or a hanging object one mile long?

There are countless oil wells and a few deep mines that are well beyond one mile in depth with continuous lengths of cable or piping hanging down the bore holes and main shafts.

They might hang but are also hanging in mud the density of which is varied to suite the process required, this supports the drill string and stops blowouts.

Also a cable or whatever from some satellite would be subject to unknown and ever changing atmospheric conditions which would render the idea somewhat difficult to implement to say the least.

A tapered cable will increase the maximum possible suspended length, although it is still not feasible with today's materials.

The moon is a non-geosync satellite and thus the project would require a two stage elevator. One geosync and the other lunar sync with a shuttle to catch up with each other as they move apart. There could be no firm attachment between the two bodies.

One of the mechatronics professors at UWS (University Of Western Sydney Australia) was working on a similar project...The idea was to make a wind generator up in the air where the enormous wind would hold the generator up there and be held down by the conductor to 'transfer the collected energy' back to earth (somewhat like a kite). While the idea and theory worked, it was the actual mass of the 'conductive rope' that was the problem.

Guest,

Even if a miracle line could be produced so-called Geosynchronous or Geostationary satellites are not truly stationary or synchronous. They drift and have to be regularly corrected or they will drift away. They also move about in the so-called stationary orbit in a figure 8 pattern.

Before the moon becomes Geosynchronous or Geostationary the sun will have become a red giant and Earth and moon will be fried.

So much for that dream.

Jon

the other thing I wonder is, as the cable is lowered from the bird., what happens to the orbital motion of the cable? doe it remain straight? or does it want to head easy with a faster orbit time because it is closer?

I have a better idea!!!! (Pipe Dream)

Why don't we replace the cable with a tube, The tube can help to keep it in position.

The tube can then be used to suck water onto the satellite. Where it can be converted to HHO using the radiation from the sun.

Half the energy can be used to keep the contraption in the sky while the balance can be fed into a down wire.

By the time the electricity reaches the ground the voltage may have increased to 11 kilo Volt (due to gravity) and may be sold to a country using power in 11 steps.

I will leave the other advantages to the imagination of CR4.

"The tube can then be used to suck water onto the satellite."

The maximum height that water can be "sucked" up a tube is 15 feet.

Do you live on a high mountain? At sea level pure water can be sucked about 33 feet up give or take!

Oops! My mistake. I was confusing 15 psi with 33 ft. H2O as atmospheric pressure. But anyway, whether 15 ft or 33 ft, it is a long way from sucking water 100 miles or more into orbit.

Not only a pipe dream, but a wire dream too. With the addition of the water it becomes a wet dream.

I had another idea: We could built a metal tower with toothed pilars (this construction could be the tallest construction in the human history!!!) and a "vehicle/elevator" (we could call it "elevahicle") having toothed wheels could roll/move up and down on these pilars. It could get electric energy for its elevation through these pilars and it could restore electric energy during its way down (due to gravity). Again, we are free from cables and all the other problems that arise from their usage.

There is a small problem with the terminology in this thread:

Geostationary/Geosinc: is an object at approx 34000 km high, remaining above the spot where it was put upon launch. As the gravitation is not always the same (earth mass is moving, the moon passes by , ...) the exact location where the satellite is will vary. But the average position will remain.

How is this possible? By it's own speed, relative to the centre of gravity which is dominant: the earths centre of gravity. This force keeping it up is exact the same as the force pulling it down, the resulting movement is a circle.

All satellites have the speed which keeps them up. Lower orbits need higher speeds as the center of gravity is closer, higher orbits need less speed.

At the geostationary orbit the speeds makes the satellite go round is exact one day, when the direction is correct chosen the satellite will remain above the correct spot on the equator.

The moon is going round in 28 day's: thus it is much further away from the earth than the geostationary orbit, and it has a speed which is a bit to high, so it moves away from us.

When the geostationary satellite needs to carry something hanging in the direction of the earth it will have to pull, this means that the speed needs to go up (higher resulting force), needing to put the satellite in a higher orbit, to keep the geostationary position.

But, while a mass is moving up the speed it has will be the same as on the earths surface. while it has to go up due the fact that is needs to go straight up.

The satellite will have to deliver the energy needed to accelerate the mass travelling up. So it will be pulled down and to the side.

Ahr I feel a drawing would help. Sorry no time.

Unless you find a fixed point up there I fear it is a difficult and costly exercise.

"Sorry no time"? You spent half hour yapping about a complete nonsense! Dude, you have WAY to much time in your hands...

"The satellite will have to deliver the energy needed to accelerate the mass travelling up. So it will be pulled down and to the side."

Check out the stories at Dave864two's link, or this direct. The latest proof-of-concept experiment used a ground-based laser to provide energy to a photovoltaic array on the cable crawler. It worked amazingly well and powered hte carrier up a 900M cable suspended from a helicopter.

The energy needed to travel up is one part of the required energy.

The mass also needs to be speeded up to stay geosinc.

• At earths surface level we are geosinc, Speed: 1667 km/hr or approx 1000 mile/hr
• At a geosinc orbit the satellite has a speed of ((7000 + 34000)* 2pi)/24 [km/hr] ≈ 10700 km/hr
• delta is 9000 km/hr
• This speed (and the force needed to accelerate) is perpendicular to the force created by the pull force of the satellite, so the up traveling mass will from slow down the top station (and the earth but this is neglectable)

To be short: the whole system needs constant new fuel to keep the top unit at the position.

The helicopter experiment was only to prove that you can power a rope crawler from a distant. the delta in speed was approx 3 km/hr, the helicopter used enormous amounts of energy to keep up in the air, at it's position, but why didn't they use a balloon?

Gwen, you are missing the point. Once in place the entire space elevator is place it becomes a simple matter of climbing the cable and the time involved is barely relevant. Since the electricity is provided by a solar powersat, who really cares how much power it takes? The main thing is that the kilogram to orbit cost is a fraction that of using rockets.

NASA has actually held contests pushing this idea. Here is a link to all kind of articles about it.

http://news.google.com/news?hl=en&source=hp&q=nasa+space+elevator&um=1&ie=UTF-8&ei=Y2f5SuW7AsHhnAefwpj5DA&sa=X&oi=news_group&ct=title&resnum=1&ved=0CA8QsQQwAA

I remember reading this years ago in Popular Science.

http://www.popsci.com/scitech/article/2004-04/space-elevator

Guest,

While spinning around on my office chair I stuck out one of my legs and noticed that my rate of spin decreased significantly.

I figured that mankind could speed up or slow down the rate of spin of the earth by grinding mountains down or building all manner of tall structures everywhere.

Of course as with other frivolous projects the progress of the people who took them on had been slowed and their true purpose in life had been deviated. They were supposed to spread all over and populate the earth but decided to stay in one place and play with each other making towers in the sand.

Jon

THE TEN COMMANDMENTS:

Now that I called your attention, let me ask:

Hey!! what happened to one of the last posts by a Guest, saying it was tried in the past and referred to a passage in the Genesis?

Was it removed for religious reasons? or in the contrary?.

Even if the content of it was biased, impossible or just against common sense, he had the right to express it and let the rest of us (grown up guys) to consider its validity, read it for its cultural value, or read it just for recreational porpuses.

Besides I didn't take a note of the chapter and versicle, and I wanted to look it up !!!

Please put it back !

Yahlasit

Guest,

Are you talking about #24?

If you have a "stationary" satellite of certain weight including the cable, and drop the cable down to earth, that will decrease the centrifugal force on it and also pull the satellite down.

If you have the same satellite, but want to approach it from below using a space shuttle that carries the cable, as soon as you attach the cable to it, it will become a load that will take the satellite out of its current orbit (into a lower one) and bringing it down.

Solution? a weightless cable that is also massless to avoid dragging by the winds, I suggest one that is made of opium dreams.

We all are going to die (old and sorrounded by our loved ones I hope) and would have never seen such a thing.

Yahlasit

If a wire or a structure were constructed that extends from the upper atmosphere to the ground, would it not become the world's greatest lightning rod? Even if it were built from non-conducting material it would provide a conductive path when it became wet from rain. Remember, this is not a structure with a large cross-section like an office buiding or an airplane. The current of the lightning discharge would be concentrated into a much smaller area. Is there any material/mechanism that could survive such frequent lightning strikes and still function?

Bmorrow,

To say nothing of the extreme frost and ice buildup.

Jon

Come on you guys, open your minds!

http://www.geek.com/articles/news/team-wins-900000-in-space-elevator-competition-20091110/

What about the effect they came across doing the 'tethered satelite to the shuttle' experiment when it built up a static charge?

If we consider the mass of the rope at the various heights, would it be travelling at the correct speed for them to be in geosync orbit, for the rope to stay in a straight line?

Difficulty. Maybe what Gwen was getting at, maybe not, but related.

For a satellite to be in geosync. it must be in orbit with a rotation of one circuit per 24Hr day. There is only the one such orbit, increase velocity and you move outward and drop behind the earth, decrease velocity and you drop to a lower orbit and appear to go faster.

Consider a mass being lowered from the satellite. As it is lowered, it's velocity would be reduced, but it's natural orbit at the lower velocity would make it rotate faster than the earth and the satellite.

Perhaps the shaft would have to be a spiral when observed from the N or S pole.

You assume that the elevator cars are in a free orbit. However, they are bound to the skyhook cable, which is a very rigid system. As soon as the car begins to descend, it it no longer in freefall. It will in fact only be in true freefall when it is at the geostationary station.

Remember the weight whirling at the end of the string. This is what we have here. The string is our skyhook, and the weight is the asteroid we have attached to the end of it. Obviously, the asteroid is not in a free orbit, it is moving much to fast at that altitude, and the tension it exerts on the cable is nothing short of incredible. The elevator cars moving up and down will be of little more significance than a bug climbing up that whirling string.

The asteroid is not hooked at all, the position is only guarantied by the game of forces.

Start adding more forces and you will find that the asteroid is moving his position.

The spiral idea is not so bad, only one problem: the stuff coming back from space has an enormous speed, which will need to be reduced before it hits the first layers of our atmosphere.

But now we assume that that the rope is laid in such a pattern that the lowering mass can use the rope to accelerate/decellerate. again energy which has to come from the masses supporting the rope.

Seems like the idea is not too far away....

http://www.newkerala.com/nkfullnews-1-145940.html

See post #32. It is the same contest as yours.

во гробе моем перейду

Исаак Юдович Ozimov

I can see why Isaac Asimov would roll over in his grave. By the way, how is the new bridge accross the horn?