Space elevators

[Agent042 No.1433012]

Dear Brainboxes of /sci/
The subject of space elevators came up in my physics lesson and my teacher said that they are impossible because everytime you send a mass up the elevator, the station at the top of the elevator will get pulled down slightly according to Newtons laws. He said that therefore you would only manage to send a few loads up before the space station was pulled down into a decaying orbit. Is this right? If not please explain why my teacher is wrong.

[Anonymous No.1433018]

Centrifugal force.

[Anonymous No.1433029]

>Centrifugal force

There's a very good reason the counterweight is past geosync orbit.

[Anonymous No.1433041]

if you made the base of the space elevator out of something that will absorb the force coming from the cargo's motion, and had the end of the elevator far enough from Earth as to hinder gravity significantly, it might work

[Anonymous No.1433048]

True. F=Gmm/r²

[Anonymous No.1433062]

>>1433041

[Agent042 No.1433078]

I think I get what you guys are saying. The outward centrifugal force creates a tension in the elevator, and balences out the weight of load going up, is that right?

[Anonymous No.1433091]

Geosync orbits end up being anything but geosynced orbits after months or maybe years, due to perturbations of other celestial bodies.

Space elevators look retarded and if an alien spaceship was ever to fly past one of them they sure would laugh their fucking asses off.

[Anonymous No.1433097]

>>1433078
Yes, all the energy needed to accelerate the cargo load to orbital velocity comes directly from the planets own angular momentum.

[Anonymous No.1433099]

Woow She's So Hot! Look At Her : http://gum.li/6q

>>4315

[Anonymous No.1433103]

>>1433091

Assuming aliens have asses.

[Anonymous No.1433123]

I'm pretty sure they would but a few thrusters on the counterweight to keep it stationary and it's orbit decaying.

[Anonymous No.1433141]

>Space elevators look retarded

How else do you propose getting anything into space without blowing all the worlds fuel?

[Anonymous No.1433144]

Any one who doubts our ability to make the space elevator work is doubting human ingenuity. I have absolutely no doubt that we could have success with a space elevator, however, this does not mean that it is the best solution.

[Anonymous No.1433171]

>>1433123
Come back when you have a clue about what you're talking about, no such thing would be needed on the counterwieght after it's in place.

[Anomynous No.1433174]

You already need propulsion systems on the counterweight to maintain the elevator's position (station keeping). Moving the counterweight slightly beyond the balance point to counteract the altitude loss of the rising payload is not complicated and certainly not a significant barrier relative to the construction of one.

[Anonymous No.1433179]

[Anonymous No.1433181]

>>1433144

It's like trying to build a bridge across atlantic ocean. A true challenge but a fucking waste of materials and money.

[Anonymous No.1433189]

>>1433144
Space elevators is the solution of choice to get large amounts of mass into orbit cheaply and safely. Assuming one has necassary cable that's strong enough to withstand the task.

Of course at the moment that is a very large assumption.

[Anonymous No.1433197]

>>1433181
>a fucking waste of materials and money

>implying reducing the cost per kg of putting things into orbit by a few orders of magnitude is a waste of money

[Anonymous No.1433198]

>>1433179
How exactly does the elevator in space decelerate in a near vacuum?

[Anomynous No.1433202]

>>1433181
>waste
And an automobile factory is a waste if you're only going to build one.

If you're building tens of thousands however...

[Anonymous No.1433217]

>>1433009

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u t wi ikskeqs hc a jotr m kkiou

[Anonymous No.1433227]

>>1433198
Where is it decelerating?

[Anonymous No.1433236]

>>1433202

Thw world will never agree to work together in such a big project.

Let's just keep it to the elegant space stations and shuttles going and coming.

[Anonymous No.1433267]

>>1433227
the part where it falls to earth

[Anonymous No.1433273]

>Space elevator

>Men on mars

pick one

[Anonymous No.1433278]

>>1433236
>elegant
>space shuttles and the iss
They have all the elegance of a tranny being rammed up the ass by a bull dike wearing a 14 inch strapon

[Anonymous No.1433289]

>>1433273
Fuck you, I pick both.

[Anomynous No.1433291]

>>1433236
The world didn't agree to work together to put a man on the moon either, but that has nothing to do with what I posted.

If we were to set out to colonize other planets or build actual space stations with spin gravity, the frequency of launches necessary to supply and maintain them approaches the point at which the cost savings of an alternative lift system such as a space elevator outweigh the expense of it's construction and maintenance.

[Anonymous No.1433293]

jesus christ im in /sci/ and im hearing people use "centrifugal" force instead of centripetal

[Anonymous No.1433300]

>>1433278
>implying that isn't the standard of elegance and beauty our society should be aspiring towards

[Anonymous No.1433315]

>>1433293


0/10, troll or retarded american victim of ignorant teachers

>>1433278

Are you telling me that a big ass elevator that is gonna make earth look like fucking popsicle is more elegant than space stations and future shuttles?

[Anonymous No.1433317]

>>1433293
>centripetal
Now you're just making shit up, you centripedo.

[Anonymous No.1433331]

>>1433171
Uh huh, why exactly wouldn't it? If it where in geosync orbit they would be required to keep the orbit decaying as loads where taken up and down the ribbon/line.

However, if you mean a colossal one relying on centripetal force then yes, I concur defeat.

Clarify please, and don't be a tosser about it.

[Anonymous No.1433326]

>>1433273
You do realize that if we had a space elevator getting a man to mars would be an immensely easier task, right?

[Anomynous No.1433333]

>>1433315
Most people don't consider tinker-toy constructions and strapping a payload onto a few thousand tons of explosive material to be elegant.

[Anonymous No.1433348]

>>1433179
>shop.jpg

Filename related, this is bullshit.

[Anonymous No.1433350]

>>1433333
You know what WAS elegant? Your 33333 get.

[Anomynous No.1433357]

>>1433350
Shiny. I'll have to treasure it.

[Anonymous No.1433359]

>>1433315
Imagine standing at the base of the elevator in the middle of the day, clear skies. You look straight up and this tether seems to stretch, curving gently due to human perception of high vertical objects, into infinity. I can't think of anything more elegant.

[Anonymous No.1433363]

>>1433315
Why would you do that, you ignorant fuck? Why make it about what country he is from? You have the intelligence of a fruit fly if you can't hold an argument without blaming the American education system.

[Anonymous No.1433371]

>>1433331
>if you mean a colossal one relying on centripetal force then yes, I concur defeat.
looks like I win then

[Anonymous No.1433373]

>>1433359
Indeed, it would be truly mind blowing. Also the greatest feat of human construction EVER.

[Anonymous No.1433376]

>>1433363

american detected

[Anonymous No.1433378]

Ultimate target for terrorism, the destruction would be vast and unimaginable.

[Anonymous No.1433380]

>>1433359
Plus a massive laser.

Awww yea...

[Anonymous No.1433381]

>>1433373

JUST GO TO A SPACE STATION OND LOOK OUT OF THE WINDOW

[Anonymous No.1433395]

Make the counterwieght far enough that the TENSION in the cable increases as the car goes down it, and decreases as it goes up.
The tension will never reach 0, however.

[Anonymous No.1433399]

ONE BARBER

ON A MISSION

CAN HIS SCISSORS SAVE THE WORLD? OR RUIN IT'S GREATEST CREATION?

[Anonymous No.1433401]

>>1433376
Yeah, no shit.That still hardly seems relevant and you still look stupid and close minded for pointing it out.

[Anonymous No.1433405]

>>1433378
True, but what value would there be in destroying it.

I know that sounds naive, but it would take a certain caliber of human to be that terrified of progress.

[Anonymous No.1433412]

>>1433405
Religious people

There, I said it

[Anonymous No.1433414]

>>1433405
>The entirity of Islam

[Anonymous No.1433415]

I have a feeling that if we ever get to do it it'll end very very bad.

I actually doubt we are going to make it if we can triple the height of the biggest skycrapers

[Anonymous No.1433419]

>>1433412
>>1433414
makes me sad

[Anonymous No.1433421]

>>1433415

>cannot*

[Anonymous No.1433422]

>>1433405

[Anonymous No.1433424]

>>1433405
Islamic archeologists hide and cover discoveries that contradict their faith. The thought nearly brings me to tears of rage.

[Anonymous No.1433429]

>>1433421
we actually can, but it's uneconomical

[Anonymous No.1433431]

Wouldn't a large enough counterweight disrupt our orbit and fuck us over?

[Anonymous No.1433432]

>>1433415
Space elevator =/= Skyscraper...

[Anonymous No.1433437]

>>1433431
>large enough
So are you asking if something capable of doing this is capable of doing this? Yes.

[Anonymous No.1433446]

Space elevators are daft. Launch loops or space fountains, followed by orbital rings are a much more feasible way to get into orbit cheaply.

[Anonymous No.1433447]

>>1433437
Large enough as in large enough for a space elevator.

[Anonymous No.1433449]

>>1433424
Really? Need sources on that before I rage. I would love to rage though.

[Anonymous No.1433474]

>>1433431

You're asking if something made on earth, from earth's materials, is going to have enough effect on earth's orbit when tethered to earth to fuck us up?

[Anonymous No.1433475]

>>1433449
Sadly I heard through second hand (from someone I trust not to make shit up) apparently they found something dated to over eight thousand years and they covered it up because it was older then the world is "supposed" to be.

[Anonymous No.1433479]

>>1433431
lets see a counterweight that weights 20000 kg, vs a planet that weighs 5900000000000000000000000 kg

Is this a serious question?

[Anonymous No.1433480]

>>1433446
The problem with such a system is that a very high velocity is necessary to launch something into orbit. Our bodies aren't able to handle the acceleration. Unless you make the loop extremely long and accelerate slowly.

[Anonymous No.1433484]

>>1433475
>over 8,000 years

son of a bitch

[Anonymous No.1433492]

>>1433479
Made from materials from said planet.

[Anonymous No.1433498]

>>1433475

>Over 8000 years

So do they not believe in dinosaurs or what?

[Anomynous No.1433501]

>>1433446
Launch loops and space fountains have their own set of problems to deal with. Which ends up being built will depend mostly on which advances in materials or energy come first.

[Anonymous No.1433517]

>>1433492
ok?

[Anonymous No.1433538]

Just use carbon, its the hardest metal known.

[Anomynous No.1433539]

>>1433492
Where the material for the counterweight comes from makes little difference.

[Anonymous No.1433541]

Who says it has to be a rigid physical structure? What about a maglev train kind of deal, but with a flexible metal cable into space instead of a rail?

[Anonymous No.1433549]

>>1433541
That's part the idea of a ribbon I believe

[Anonymous No.1433569]

>>1433498
Lol they literally don't. Some religious people believe satan put them here to fool people.

[Anonymous No.1433593]

>>1433549
Where can I read up on this? I haven't heard any real about it. Who was the famous scifi author who thought this was the greatest idea ever?

[Anonymous No.1433600]

>>1433480

It's designed to be long enough to launch humans into space. Acceleration at 3G will send you to LEO when you come off the end of the loop.

The thing about a launch loop is while it doesn't have the capacity of an elevator, it's easier and simpler to build. We should start with something smaller before we try getting a cable to Geo. We have far too little experience with megastructures to start with the space elevator.

[Day Man !YGt0AhF/ro No.1433620]

suprised i haven't seen people quoting this yet
http://en.wikipedia.org/wiki/Space_elevator

[Anonymous No.1433674]

>>1433593
You're thinking of an Arthur C Clarke book. But what really got me into space elevators was seeing this video and then simply reading a lil wikipedia on them.

http://www.youtube.com/watch?v=rG8LfQDcqGA

[Anonymous No.1433925]

>>1433620
You spelled surprised wrong. It's okay, I do it all the time.

[Anomynous No.1433955]

>>1433600
Though with a launch loop you have to deal with a semi-elastic cable thousands of miles long moving at thousands of kilometers an hour.

At least most of the problems with a space elevator are static problems.

And don't get me started on the energy throughput necessary for a space fountain.

[Anonymous No.1434080]

>>1433539

It makes a whole lot of difference.
If the mass of the counterweight comes from the object itself, the net result is very little change in orbit.

[Anomynous No.1434104]

>>1434080
No, given that even if you took it from somewhere else, the difference in the center of gravity is still less than the width of a hydrogen atom, it still matters very little.

[Anonymous No.1434262]

[Anonymous No.1434270]

[Anonymous No.1434274]

[Anonymous No.1434276]

[Anonymous No.1434280]

[Anonymous No.1434283]

[Anonymous No.1434288]

Today’s famous detailed construction plan is established by Dr. Bradley C. Edwards and his collaborators. It is one of so-called “bootstrap”. Its processes are as below.
(1) Launch rockets loading cables for the Elevator, working spacecraft and fuels to low earth orbit (LEO) of 300km in altitude.
(2) Assemble the spacecraft with the contents of the payload in the LEO and reach to the geostationary earth orbit (GEO)
(3) The spacecraft goes up releasing the cable from the GEO. Finally the end of the cable reaches to the base station. The spacecraft is placed at another end of the cable as counter mass. These process makes it enable to lift 1 ton of elevator vehicle for more work (Edwards call it “Cruiser")
(4) Following cruiser starts from the base station drawing second, third and more cables. The cables are unified and reinforced increasingly. Cruisers after going up become counter masses at the end every time.
(5) Start to totally work when the unified cable has strength enough to transport stuffs and human.

--This plan is precious and has greatly contributed to studies on the Space Elevator.
However, it also has problems as follows.
* Maintenance is its cable because the first cable will wear when the last cable is completed and application starts.
* It can not correct its bending caused by Coriolis force or the gravity.
* There is fear of radiation, collision with debris or armed attack
* It is difficult to build stations at LEO or HEO
These problems are common for almost all models. But they must be solved anyway.

[Anonymous No.1434289]

>An alien species of intelligent or sentient life passes by.
>They still use ugly looking space elevators
>Laughingaliens.jpg

[Anonymous No.1434300]

The amazingly efficient thing about space elevators is that if you're bringing down as much weight as you're sending up, you only need to put in energy to overcome friction and other losses (assuming you use some form of regenerative braking)

[Anonymous No.1434304]

>>1434289
lol

[Anonymous No.1434322]

How would you go about supporting a space elevator anyways?

[Anonymous No.1434327]

>>1433179

wut

[Anonymous No.1434331]

>>1434289
hey I made that pic.
good old reddit

[‏ No.1434336]

>>1434327
It's an awesome mspaint rendition of a space elevator crashing down to the earth. I think it would cover a much larger area.

>>1434322
Perhaps if you were literate you would understand. L2Gravity/Intertia/Orbital Mechanics.

[Anonymous No.1434341]

>>1434331
Did I mention that when I am looking for pictures google is my best friend for the job?

[Anonymous No.1434351]

>>1434336
Explain it to an "Illiterate" then.

[Anonymous No.1434353]

>>1434341
COOL!
My pic has hit the big time!

[Anonymous No.1434408]

Space fountain

[Anomynous No.1434443]

>>1434408
Energy consumption of a country.

Comes crashing down if that's interrupted.

[Anonymous No.1434475]

Ok... checked out that wikipedia article... interesting read.

Every time we send something up, we slightly slow the rotation of the Earth? What do we do then? Add more leap years? After a trillion trips, change to 25 hour days?

[Anonymous No.1434493]

>>1434104

Did you even read the message chain?

Let's assume that we take chunk out of the earth the size of the moon.
Like, you know, the moon.
Makes fuck all difference.

[Anomynous No.1434498]

>>1434475
it would take thousands of years of use to slow the rotation of the earth perceptibly. it's really not that big a problem unless you're intending to send trillions of tons up.

[Anonymous No.1434500]

>>1434280
>>1434283

This is one of the main problems I have with space elevators. The cable needs protection and other supporting structures along it's length, but it just can't cope with the extra load. Even theoreticaly perfect carbon nanotubes are barely strong enough to support their own weight to geostationary, let alone the weight of 22,000 km of stuff along it's length.

I honestly think an active structure like a launch loop or space fountain would be easier to deal with, in the long run.

[Anonymous No.1434504]

>>1434475
You'd need to launch quite a bit of mass for that to happen lol. Would have no worry if we started building them in space out of asteroids or some such.

[Anomynous No.1434511]

>>1434493
Care to justify why you would need a counterweight that large? it doesn't need to be a millimeter above geosynch, you can put a much, much smaller counterweight a hundred kilometers further up.

[Anonymous No.1434512]

>>1434475
The time of a year stays the same if the object is in orbit, the length of a day changes.

Since it's minute, however, we change the way leapyears are formatted.

[Anonymous No.1434513]

>>1434493

I think you are severely over-estimating the required mass of the counterweight. I doubt it would need to be more than a couple of hundred tons, not a lump of rock the size of the moon.

[Anonymous No.1434515]

>>1434498
Well, if we assume that this space elevator is a permanent structure, in the least, its around that long.

Plus, if we're doing this cheaply, we're sending stuff up and down, tons at a time. Those add up.

[Anonymous No.1434525]

>>1434511

We don't. The principle was that if you take the object from the earth, then it will have far less of an effect than if you built it on Mars, and imported it in.

[Anomynous No.1434526]

>>1434500
It's a materials problem. The launch loop has stability and resonance problems. The Space fountain has energy throughput problems.

As I said upthread: which ends up being built will depend on what advances come around first and/or are available when construction planning begins.

[Anonymous No.1434530]

>>1434515

But the thing is, after a while we'll be sending just as much down as we're sending up. We may even end up sending more stuff down then up if lunar or asteroid mining becomes a big thing.

[Anonymous No.1434531]

>>1434515
>Bringing them down

No, it doesn't add up. It adds, then subtracts, then adds, etc.
It has the same effect as leaving the lift halfway up.

[Anomynous No.1434534]

>>1434525
So your example doesn't matter unless we do something we don't need to do?

[Anomynous No.1434540]

>>1434530
>>1434531
That may be the case, but in general the problem is getting things OUT of the gravity well, not into.

[Anonymous No.1434543]

>>1434540
Make your post clearer, that doesn't make sense.

[Anonymous No.1434554]

>>1434531
>>1434530
So you're saying sending stuff down to Earth from space detracts from the slowing of Earth's rotation caused by the sending of things up. Didn't realize that.

Is the effect of slowing/accelerating (minutely) the Earth's rotation a result of the shift in (relatively) tiny amounts of mass? Like ice skaters pulling in arms to speed up.

Oooh... I needed to think that through with my fingers.

[Anonymous No.1434559]

>>1434526

I think the main thing I like about the two structures is that you don't have to put anything into orbit beforehand. Everything can be built on the ground and it lifts itself up.

But as you said, it depends on what tech becomes available first. I just feel that space elevators are over-hyped, when all these technologies are possible solutions.

[Anonymous No.1434571]

>>1434543
I believe he is saying that, in the early to mid-stages of use, its likely that much more will be sent up into space rather than from space down to Earth. And afterward, in later use its likely to be around the same.

[Anomynous No.1434575]

>>1434543
The angular velocity imparted on the payloads moving up or down the space elevator only matters when there is a significant imbalance in the cargo transfer. More goes up than comes down? Earth's spin slows down (Longer days). More does down than comes up? Earth's spin speeds up (shorter days).

They were asserting that it would eventually balance out without making any real argument. I pointed out that, in general, it is more difficult to lift things out of the Earth's gravity well than it is to move things into it. Therefore: it will more often be used to lift things out of the gravity well.

For what it is worth: I have no problem with longer days; In fact, I think it would be pretty great to have a couple more hours a day, even if t meant fewer days in a year.

[Anonymous No.1434577]

>>1434540

It's more once we've got everything we want to get out of the gravity well in orbit. I doubt the Earth would have slowed down considerably once we started bringing stuff back down to Earth, especially as bringing it back will probably give us a good lump of energy as it brakes going down the cable.

[Anonymous No.1434587]

science teacher is a fucking retard; needs to read up on the actual mechanics.

[Anomynous No.1434590]

>>1434559
They are possibilities, yes, and deserve their fair mention, but the topic at hand is a space elevator.

[Anonymous No.1434592]

>>1434575

That might be the case theoretically, but you'd have to be doing extreme amounts of one action or the other to create even the slightest perceptible change. The Earth's a big place, man.

[Anomynous No.1434596]

>>1434577
But not more energy than we got sending it up.

[Anomynous No.1434599]

>>1434592
I am well aware of that. I mentioned upthread that it would take trillions of tons difference either way to make a perceptible difference.

[Anonymous No.1434607]

>>1434596

We're not talking about making free energy, we're talking about recouping the costs of sending the thing up in the first place.

[Anomynous No.1434621]

>>1434607
same argument applies.

[Anonymous No.1434633]

>>1434621

Not really, because nobody's arguing that you can achieve some sort of 1-to-1 energy feedback. It does reduce the cost of sending the elevator up though, and since we're sending the elevator up regardless we may as well make the effort to get some cash from the actual action.

[Anonymous No.1434656]

An orbit is actually in equilibrium between the gravitational force created by earth's mass and the satellite's inertia. There's no such thing as centrifugal "force". It's a fictive force. What's happening is that when you load the satellite with people, the satellite's mass will rise higher, but also its inertia. If we approximate its orbit to be circular, then you can compare m1v²/r(circular motion due to acceleration towards center) to Gm1m2/r² (gravitational force)(m1 is the satellite's mass, m2 is the Earth's mass, G is the gravitational constant and r, the distance between the satellite and the orbit's center(close to Earth's center of mass)). Isolate r and it gives you r=Gm2/v². Now what you would like to do is to compare radius 1 (the original) to radius 2 (the new one). If we set G and v to be the same in both cases, you get r2/r1 = m2*/m2. Wait what happened? It seems that the satellite's orbit will only depend on Earth's mass or speed if you make it vary.

[Anonymous No.1434764]

Can anyone easily explain Godell's proof for his incompleteness theorems?
Wikipedia doesnt get into it

[Day Man !YGt0AhF/ro No.1434774]

>>1433925
I did, didn't I?
Thanks for bringing that to my attention.

[Anonymous No.1434801]

clearly the solution is bringings the entire earth into space instead of just a little bit for our spaceships. the earth can be our spaceships;

[Anonymous No.1434854]

Are there any situations when the consequences have the same exact outcome?

[Anonymous No.1434855]

space elevator = gayest shit evar

[Anomynous No.1434881]

>>1434855
America can, should, will, and MUST build the biggest phallus!

Then we need the pelvic thrusters to take us right into Mars' gaping rectum.

[Anonymous No.1436591]

>>1434854
iz dat sum P = NP?