Space Elevator Kickstarter

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Space Elevator Kickstarter

Postby Patren » Mon Aug 27, 2012 1:42 pm UTC

I have to say, I'm rather disappointed that with all my Facebook liking of science/space project communities that I found out about this from Yahoo News. (Perhaps there is a reason for that and as soon as I posted this I receive thousands of responses about how the guy is a fraud.)

Anyway this company is long term goal is to build a space elevator...on the moon! While not the earth, I still think that's pretty cool.

http://www.kickstarter.com/projects/mic ... a-tethered

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Re: Space Elevator Kickstarter

Postby SlyReaper » Mon Aug 27, 2012 2:01 pm UTC

Given that the moon rotates so much more slowly than the Earth, wouldn't a space elevator need to be much much longer? How exactly is that "easier" than one tethered to the Earth?
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Re: Space Elevator Kickstarter

Postby eran_rathan » Mon Aug 27, 2012 2:18 pm UTC

SlyReaper wrote:Given that the moon rotates so much more slowly than the Earth, wouldn't a space elevator need to be much much longer? How exactly is that "easier" than one tethered to the Earth?


no atmosphere, for starters.
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Re: Space Elevator Kickstarter

Postby Patren » Mon Aug 27, 2012 2:41 pm UTC

Sadly I don't know. Unless you're thinking they're going to build it on the moon and connect it to the earth. Which is not the plan. They're just building it from the surface of the moon out into space.

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Re: Space Elevator Kickstarter

Postby SlyReaper » Mon Aug 27, 2012 2:52 pm UTC

Connecting it to the Earth would never be an option anyway. What makes you think that was what I had in mind?

A lunar synchronous orbit would be an extreme distance away from the moon compared to the distance a geosynchronous is away from the Earth. The atmosphere would only influence the lower hundred km or so of the cable which would be tens of thousands of km long, so I'm pretty sure you don't gain anything by planting it on the moon rather than the Earth.

Well I suppose there would be one thing... you wouldn't get LEO satellites on equatorial orbits colliding with it.
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Re: Space Elevator Kickstarter

Postby Wnderer » Mon Aug 27, 2012 2:56 pm UTC

SlyReaper wrote:Given that the moon rotates so much more slowly than the Earth, wouldn't a space elevator need to be much much longer? How exactly is that "easier" than one tethered to the Earth?


Does a lunar space elevator need to be any specific length? The moon is tidal locked to the earth. I think a space elevator would also be tidal locked. It just needs to be long enough to not fall back to the moon but be pulled toward the earth.

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Re: Space Elevator Kickstarter

Postby Zamfir » Mon Aug 27, 2012 2:58 pm UTC

There's no lunar equivalent to a geostationary orbit, I think, because its too close to earth. Instead you would have to build to a Lagrange point and somewhat beyond. L1 and L2 are something like 60,000 km from the moon. Which is more than earth-geostationary, but the stresses in the cable would be far lower because of the lower gravity.

Though L1 and L2 are unstable points, and L4 and L5 are more like 300,000 km away. But perhaps a cable would act as stabilizer, I don't know that.

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Re: Space Elevator Kickstarter

Postby Sero » Mon Aug 27, 2012 3:06 pm UTC

Well, it still has utility for any trip to the moon. Or rather, any trip to the moon that involves a return trip, since you wouldn't have to boost fuel for the (probably) most expensive part of the return trip, lifting off from the moon's surface. Of course, there's no denying an Earth-based space elevator would be of far greater utility, so unless there's some compelling technical reason it would be more feasible to put one on the moon, I'm confused as well.
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Re: Space Elevator Kickstarter

Postby Heisenberg » Mon Aug 27, 2012 3:14 pm UTC

The technical reason is that we don't have a material strong enough to build an Earth space elevator out of. And it could be used to land supplies on the moon as well as take off.

I don't know if we have one that would go all the way to Lunar L1, but I'm a skeptical that the 1/6th gravity will make up for that added distance. But if we taper the cable... maybe?

Now I'm imagining Neil Armstrong ziplining down to the lunar surface.

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Re: Space Elevator Kickstarter

Postby Patren » Mon Aug 27, 2012 3:17 pm UTC

SlyReaper wrote:What makes you think that was what I had in mind?


Oh I didn't really think that's what you meant. I have absolutely no knowledge on the science of a space elevator which is why I said Sadly I do not know. The only thing I did know an answer to was if by any chance you thought they were planning on linking the two so I just tacked that on.

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Re: Space Elevator Kickstarter

Postby Wnderer » Mon Aug 27, 2012 3:22 pm UTC

I found the Wikipedia page on Lunar Space Elevators.

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

Some points it makes.

It would have to be built to one of the Lagrange points.
It could be built with existing technology.
It would be too slow to carry people.

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Re: Space Elevator Kickstarter

Postby Tyndmyr » Mon Aug 27, 2012 3:45 pm UTC

Well, this Kickstarter isn't really for a Space Elevator. It's for an attempt to beat the current record at rope climbing robots. This is interesting, and perhaps a worthy goal in it's own right, but this is probably not a major factor in space elevator development.

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Re: Space Elevator Kickstarter

Postby bigglesworth » Mon Aug 27, 2012 4:11 pm UTC

I'm actually much more interested in their concept for a temporary tall structure than their spaceflight ideas.
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Re: Space Elevator Kickstarter

Postby Tyndmyr » Mon Aug 27, 2012 4:19 pm UTC

bigglesworth wrote:I'm actually much more interested in their concept for a temporary tall structure than their spaceflight ideas.


Fair. Personally, I'm excited by balloon tech...we can basically scrape orbit with high-altitude balloons currently, and I'd imagine some sat-like potential utility here. It's an area with a lot of room for exploration and development, I feel...I'm not against any research into this.

Now, the "space elevator" thing probably gets them a lot of attention, but it's definitely not the only angle to consider.

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Re: Space Elevator Kickstarter

Postby omgryebread » Mon Aug 27, 2012 4:49 pm UTC

Be interesting to see the legal issues here. There's no real framework for claiming property on the moon. Before any space elevator there, they'd need to resolve if they can even legally do it, which probably involves a new international treaty.
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Re: Space Elevator Kickstarter

Postby SlyReaper » Mon Aug 27, 2012 5:06 pm UTC

That didn't stop the leftpondians planting flags there. :P
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Re: Space Elevator Kickstarter

Postby Роберт » Mon Aug 27, 2012 5:08 pm UTC

omgryebread wrote:Be interesting to see the legal issues here. There's no real framework for claiming property on the moon. Before any space elevator there, they'd need to resolve if they can even legally do it, which probably involves a new international treaty.

At this point, if you get there and put it to good use, I don't see anybody stopping you. That is something that would need to get resolved eventually, though.
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Re: Space Elevator Kickstarter

Postby Tyndmyr » Mon Aug 27, 2012 5:12 pm UTC

omgryebread wrote:Be interesting to see the legal issues here. There's no real framework for claiming property on the moon. Before any space elevator there, they'd need to resolve if they can even legally do it, which probably involves a new international treaty.


Meh. What are they gonna do, send a lander up there to take your things?

Doing it will force the legal issue, whereas relying on legal accomplishments first for something that right now seems pretty remote as a possibility is unlikely to ever get anywhere.

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Re: Space Elevator Kickstarter

Postby Heisenberg » Mon Aug 27, 2012 5:16 pm UTC

omgryebread wrote:Be interesting to see the legal issues here. There's no real framework for claiming property on the moon. Before any space elevator there, they'd need to resolve if they can even legally do it, which probably involves a new international treaty.

Meh, it doesn't even need to touch the ground. It's just a rope hanging 3 feet up with a note on it: $1000 to Climb.

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Re: Space Elevator Kickstarter

Postby SlyReaper » Mon Aug 27, 2012 5:25 pm UTC

Heisenberg wrote:
omgryebread wrote:Be interesting to see the legal issues here. There's no real framework for claiming property on the moon. Before any space elevator there, they'd need to resolve if they can even legally do it, which probably involves a new international treaty.

Meh, it doesn't even need to touch the ground. It's just a rope hanging 3 feet up with a note on it: $1000 to Climb.

If it doesn't touch the ground, it would fly off into space.
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Re: Space Elevator Kickstarter

Postby hoppypress » Mon Aug 27, 2012 5:38 pm UTC

238,900 miles is a long elevator ride. Will beverages be served?
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Re: Space Elevator Kickstarter

Postby SlyReaper » Mon Aug 27, 2012 5:43 pm UTC

I think the elevator music would be a bigger problem.
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Re: Space Elevator Kickstarter

Postby Heisenberg » Mon Aug 27, 2012 6:36 pm UTC

SlyReaper wrote:If it doesn't touch the ground, it would fly off into space.

Why? The mass at L1 would be relatively stable, and the cable would keep pointing at the moon due to gravity.

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Re: Space Elevator Kickstarter

Postby SlyReaper » Mon Aug 27, 2012 6:38 pm UTC

The centre of mass would have to be above the Lagrange point in order to keep the cable under tension.
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Re: Space Elevator Kickstarter

Postby Heisenberg » Mon Aug 27, 2012 6:41 pm UTC

Gravity would keep a hanging cable in tension.

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Re: Space Elevator Kickstarter

Postby Роберт » Mon Aug 27, 2012 6:49 pm UTC

Heisenberg wrote:Gravity would keep a hanging cable in tension.

And it would somehow magically stay at the precise orbital pattern of 3 feet off the ground? That's impressive.
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Re: Space Elevator Kickstarter

Postby Heisenberg » Mon Aug 27, 2012 7:05 pm UTC

Yup. Remember, magic is just stuff science hasn't made boring yet.

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Re: Space Elevator Kickstarter

Postby Wnderer » Mon Aug 27, 2012 9:25 pm UTC

Actually the original 1972 paper also just uses Earths gravity to hold the line in tension and makes no mention of the Lagrange points or solar powered elevators. I don't know why future designers abandoned the basic concept.

An alternative Lunar-Earth transportation system concept is now being proposed, which potentially can reduce the transportation energy cost to a negligible expense, although some of the features of the concept stagger the imagination. No chemical energy fuels need be brought from the Earth to the Moon, or be made on the Moon. It is necessary to the understanding of the concept to change one's visualization of what lies between Moon and Earth. Analogously imagine a small model of two adjacent pits in the ground, the shallower one containing water. Then note that the water from the shallower pit may be siphoned into the deeper one without addition of external energy, provided that a hose is provided and the siphoning process is started. Such a siphoning process will power itself provided that the work applied to the mass being transferred down the deeper slope is greater than the work required to lift the mass up from the shallower side. The Earth and its moon, Luna, may be pictured as two adjacent gravity pits in space, the pit corresponding the the Moon being much less deep than that of the Earth.


A cable, or other tension structure, if it is attached to the Moon's surface and extends up out of the Moon's gravity pit toward Earth far enough so that part of it hangs down part way into Earth's gravity pit, will stay there in place without external energy applied, if the weight of the part of the cable in Earth's pit is at least as great as the weight in the Moon's pit


lunarspaceelevator.mooncable1.gif


http://www.kestsgeo.com/1techconcepts/d ... r1972.html

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Re: Space Elevator Kickstarter

Postby Роберт » Mon Aug 27, 2012 9:36 pm UTC

Wnderer wrote:
A cable, or other tension structure, if it is attached to the Moon's surface and extends up out of the Moon's gravity pit toward Earth far enough so that part of it hangs down part way into Earth's gravity pit, will stay there in place without external energy applied, if the weight of the part of the cable in Earth's pit is at least as great as the weight in the Moon's pit
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Re: Space Elevator Kickstarter

Postby Wnderer » Mon Aug 27, 2012 9:50 pm UTC

Роберт wrote:
Wnderer wrote:
A cable, or other tension structure, if it is attached to the Moon's surface and extends up out of the Moon's gravity pit toward Earth far enough so that part of it hangs down part way into Earth's gravity pit, will stay there in place without external energy applied, if the weight of the part of the cable in Earth's pit is at least as great as the weight in the Moon's pit


Yes. It needs to be attached to the moon. I was thinking about the Lagrange points, but maybe the cable would naturally be pulled through the Lagrange points. But then there are two of those between the earth and moon. I think this drawing falls between them.

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Re: Space Elevator Kickstarter

Postby Derek » Mon Aug 27, 2012 10:31 pm UTC

Wnderer wrote:Actually the original 1972 paper also just uses Earths gravity to hold the line in tension and makes no mention of the Lagrange points or solar powered elevators. I don't know why future designers abandoned the basic concept.

An alternative Lunar-Earth transportation system concept is now being proposed, which potentially can reduce the transportation energy cost to a negligible expense, although some of the features of the concept stagger the imagination. No chemical energy fuels need be brought from the Earth to the Moon, or be made on the Moon. It is necessary to the understanding of the concept to change one's visualization of what lies between Moon and Earth. Analogously imagine a small model of two adjacent pits in the ground, the shallower one containing water. Then note that the water from the shallower pit may be siphoned into the deeper one without addition of external energy, provided that a hose is provided and the siphoning process is started. Such a siphoning process will power itself provided that the work applied to the mass being transferred down the deeper slope is greater than the work required to lift the mass up from the shallower side. The Earth and its moon, Luna, may be pictured as two adjacent gravity pits in space, the pit corresponding the the Moon being much less deep than that of the Earth.


A cable, or other tension structure, if it is attached to the Moon's surface and extends up out of the Moon's gravity pit toward Earth far enough so that part of it hangs down part way into Earth's gravity pit, will stay there in place without external energy applied, if the weight of the part of the cable in Earth's pit is at least as great as the weight in the Moon's pit


lunarspaceelevator.mooncable1.gif


http://www.kestsgeo.com/1techconcepts/d ... r1972.html

This description is equivalent to using a Lagrange point. The point where the elevator starts to "hang down part way into Earth's graviy pit"? That point is called L1.

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Re: Space Elevator Kickstarter

Postby Iulus Cofield » Tue Aug 28, 2012 12:51 am UTC

Wouldn't a space elevator between the earth and the moon go, like, really fast?

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Re: Space Elevator Kickstarter

Postby poxic » Tue Aug 28, 2012 1:10 am UTC

Iulus Cofield wrote:Wouldn't a space elevator between the earth and the moon go, like, really fast?

Wouldn't it, like, get snapped by the movement of the moon orbiting the Earth?
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Re: Space Elevator Kickstarter

Postby Iulus Cofield » Tue Aug 28, 2012 1:16 am UTC

Implying I can physics.

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Re: Space Elevator Kickstarter

Postby Wnderer » Tue Aug 28, 2012 1:32 am UTC

Derek wrote:This description is equivalent to using a Lagrange point. The point where the elevator starts to "hang down part way into Earth's graviy pit"? That point is called L1.


That makes sense.

Thanks

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Re: Space Elevator Kickstarter

Postby gmalivuk » Tue Aug 28, 2012 1:34 am UTC

Wnderer wrote:I was thinking about the Lagrange points, but maybe the cable would naturally be pulled through the Lagrange points. But then there are two of those between the earth and moon.
No, only L1 is between the two, and it marks the point where something goes from being pulled toward the Moon to being pulled toward the Earth.
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Re: Space Elevator Kickstarter

Postby Jahoclave » Tue Aug 28, 2012 5:17 am UTC

hoppypress wrote:238,900 miles is a long elevator ride. Will beverages be served?

Yes, but they will be almost, but not entirely, unlike beverages.

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Re: Space Elevator Kickstarter

Postby AvatarIII » Tue Aug 28, 2012 8:11 am UTC

gmalivuk wrote:
Wnderer wrote:I was thinking about the Lagrange points, but maybe the cable would naturally be pulled through the Lagrange points. But then there are two of those between the earth and moon.
No, only L1 is between the two, and it marks the point where something goes from being pulled toward the Moon to being pulled toward the Earth.


so the centre of gravity of the cable would have to be in L1?

iirc, one of the hardest things about going to the moon is landing with no air resistance, a space elevator would certainly help on that front.

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Re: Space Elevator Kickstarter

Postby Soralin » Tue Aug 28, 2012 9:07 am UTC

Heisenberg wrote:
SlyReaper wrote:If it doesn't touch the ground, it would fly off into space.

Why? The mass at L1 would be relatively stable, and the cable would keep pointing at the moon due to gravity.

And what happens when you go to move cargo up or down your floating cable? Newton's third law, cargo goes up, cable goes down, and vice-versa. That's why you want the thing to be attached to the ground, and for the center of mass to be a bit further out than it would need to be to just float there.

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Re: Space Elevator Kickstarter

Postby SlyReaper » Tue Aug 28, 2012 9:09 am UTC

AvatarIII wrote:
gmalivuk wrote:
Wnderer wrote:I was thinking about the Lagrange points, but maybe the cable would naturally be pulled through the Lagrange points. But then there are two of those between the earth and moon.
No, only L1 is between the two, and it marks the point where something goes from being pulled toward the Moon to being pulled toward the Earth.


so the centre of gravity of the cable would have to be in L1?

iirc, one of the hardest things about going to the moon is landing with no air resistance, a space elevator would certainly help on that front.

The center of gravity would have to be above the L1 point, otherwise anything climbing the cable would pull the whole thing down.
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