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/sci/ - Science & Math

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7142282 No.7142282 [Reply] [Original]

Is the construction of a space elevator actually possible?

Would it be useful for future space programs?

>> No.7142286

No.

>> No.7142306

Yes.

>> No.7142314

>>7142282
I hope so.

>> No.7142335

>>7142282
Will we have to stand on the "ceiling" or will we stand on the floor of the space elevator

>> No.7142341

>>7142282
Of course it is possible. And, of course, it will never happen.

>> No.7142374

>>7142341
It will give a huge advantage to the nations that build it first

I do actually think that it will never happen due to technical difficulties (costs, space trash etc.)

>> No.7142406

yes, they're working on it now

over 30 feet thick, nothing but hemp rope

>> No.7142418

>>7142341
>Of course it is possible
We don't even know of a material that could endure such stress.

>> No.7142424

>>7142282
A space elevator from Earth is outside the limits of current materials science, and it doesn't look like it'll be within the limits for a long time - if ever. Things like pure graphene or carbon nanotubes could potentially hold it, but the technology needed to manufacture 35,000 km long atomically-perfect single molecules is far outside our abilities. (and you have to keep it that perfect, or the strength goes down a lot.)

And then there's the problem of how you'd construct it even if you did have the materials.

Space elevators, however, could be very useful on the Moon and Mars, where the low gravity means that conventional materials already in use could be used to construct a space elevator.

>> No.7142497

>>7142424
This is the best answer I seen I some time. I was going to post something similar but seeing as it is here already. Let me add some additional detail OP probably doesn't need, just to confuses most people.

One is the cost and political issues which means it will never happen in a gravity field like the one on earth. While we could possibly build one it would not meet any durability or safety standards, and the funny part is huge international mega projects don't get green lit if odds are very good it will just break in a few weeks, assuming nobody bombs it first. That is if any one is willing to pay for it as the current price for such things is far too expensive, even for an internationally backed mega projects.

We could also strengthen it beyond material limits by making it an active structure. The issues with that is that it constantly need power to keep from collapsing. The power goes down the whole thing goes down permanently. Also it takes a huge amount of power so that one would constantly have to pay for making any trips far too expensive. Also if the structure got damaged there is a good chance all that energy could be released at once in a blast similar to that of a nuke, which scares people from wanting to build a trading city around it which you would need if you were even going to attempt to pay the power bill.

>> No.7142755

What about launch loop?
Wouldn't it be almost as good as space elevator and physically possible to build right now?

>> No.7142757
File: 828 KB, 831x573, lofstrom.png [View same] [iqdb] [saucenao] [google]
7142757

>>7142755

>> No.7142802

The kicker is that even if we had it, it wouldn't provide us much of an advantage.

A economically reusable chemical rocket is much, much easier and cheaper to develop. I think we can all agree on that, right?

"But Anon", you might be thinking, "it would be less energy efficient than a space elevator!"

Not likely. Chemical rockets are around 10% energy efficient at converting chemical energy to orbital energy. That might sound low, but it's pretty good.

Space elevators are expected to be under 1% energy efficient. If the climber is heavy compared to the payload, that's all waste. There isn't mass allowance to build power lines into the cable, and they'd be far too long. So what you end up with is a microwave power transmission system, with a small, inefficient receiving antenna. Most of your power goes to transmission losses. There would also be friction losses.

Besides, a space elevator would be sloooow. A chemical rocket accelerates continuously and goes to orbit in minutes, but a space elevator ride would be, well... an elevator ride. A twenty-thousand-mile elevator ride, around the world at ground vehicle pace uphill all the way.

>> No.7142875

China MIGHT do it. They're planning to start moon colonization for resource gains. There's no denying that it would be vastly superior to rockets.

>> No.7142886

>>7142418
the hardest metal known to man

>> No.7142889

>>7142886

the hardest metal known to man isn't strong enough

>> No.7142892

Part 1/3

I decided to investigate documented facts and then run the fairly simple numbers. I could have used an integral but decided instead to just run a Free BASIC program, totaling up the tension in the ribbon for each meter added to the 42 million required for the elevator run.

The results show why the media keeps dallying with the idea. But hard-nosed engineers already know it's impossible.

First we have to acknowledge that such a thing is material. And being material, it involves the strongest possible stuff, that being carbon nanotubes (CN). The strongest atomic bond is C=C, the double-covalent bond between two carbon atoms. This is Peak Stress. We can find nothing stronger.

The maximum CN stress is 300 GPa in theory. Common lab attempts only produce a fraction of that; well below 100 GPa. There have been some observations around 150 GPa. And this is not for a lack of trying.

But a manufacturing process can't produce lab numbers in quantity. And we still have to take into account the safety factor.

>> No.7142894

>>7142889
hater

>> No.7142905

>>7142418
Yet

>> No.7142906

Part 2/3

My calculations show a 1.3g/cc CN material that's 1 meter wide by 1nm thick (1-10 nm is the commonly stated goal for such a ribbon) has to endure 70 N at the top connection point. That doesn't sound like much, but it's so thin that it becomes 70 GPa when applied to the cross-section. The density can vary but 1.3g/cc is a practical minimum considering you're going to be making megameters of the stuff.

Then we need to consider the safety factor (SF). This is an engineering necessity. The minimum SF for well-established building codes is 2.0. But aerospace applications should be higher, since the building SF assumes there's significant redundancy in structural members (which anyone looking at a building can see). I'd say that the SF for the space elevator should be at least 2.5, regardless of how many ribbons you use.

That makes the unloaded stress something like 175 GPa. And we haven't taken into account wind loads and usage loads.

Get it yet? The cable (ribbon) alone weighs 70 N upon itself, producing 70 GPa, which in the safety factor becomes 175 GPa. Add just ONE KILOGRAM (9.8 N at the bottom) in usage to that ribbon, and again taking into account the safety factor (becomes 25 N), you've already increased the load on the ribbon by 14%, to 200 GPa. We've made nothing even close to 200 GPa in tensile strength. Even the 150 GPa stuff won't work, assuming the manufactured stuff ends up as strong as the lab samples.

>> No.7142911

>if escalator breaks, still useable
>seriously preferring elevator

>> No.7142913

Part 3/3

Wind loads would probably push the 200 GPa number up some more. How much, I don't know. But even setting a minimum 220 GPa number would still require a 200 GPa ribbon.

And say you even had that ribbon. That's just for ONE KILOGRAM of transport. For every kg of transport, you'd need one ribbon. There's really no way you've going to get a transport capsule plus cargo to mass less than 10 tons; remember the capsule has to have pressurized life support and emergency systems installed. Call it 10000 kg. That means you'd have to construct ten thousand ribbons, meaning your manufactory would have to produce 420 billion meters of ribbon. That's 420 billion meters where each meter has to be scanned or tested for quality assurance.

Pending: Calculation of centrifugal force.

>> No.7142924

>>7142911
>implying watching the entire thing collapse from space to the earth isn't the sole reason I want the damn thing built
Didn't you play with blocks as a kid?
What is the best part of the blocks, building the tower, or knocking it down?

>> No.7142929

>>7142913
>>7142906
>>7142892
tl;dnr

>> No.7142931

>>7142924

realizing you just wasted millions of dollars?

>> No.7142946

>>7142931
>not liking fun
Ok what ever you fucking autist

I'm going to go play with my blocks

>> No.7142988

>>7142886
Diamond.

>> No.7143025

>>7142988

good luck with that

>> No.7143064

Ignore developing a material for a cable. How do you deploy a cable to geosynchronous orbit without it flopping around and falling on the surface?

>> No.7143086

>>7143064
It's like having a satellite orbiting earth that has a string hanging down from it that touches the surface

I think

>> No.7143192

They talk about CNT's but it's really difficult to synthesize long enough units.

>> No.7143205

>>7142913
>>7142906
>>7142892
You didn't account for tapering the cable.

>> No.7143239

>>7142886
Tungsten obviously

>> No.7143244

>>7143205
>You didn't account for tapering the cable.

Neither do modern designs, using carbon-nanotube ribbons.

>> No.7143280
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7143280

>>7142988

>> No.7143354

>>7142282
the funny thing is rockets are actually more energy efficient(if they aren't thrown away)

>> No.7143441
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7143441

Won't happen because 1) it's ridiculous(*), and 2) it's a short term solution that will be only useful for the next 20~ years before - hopefully - warp drives are invented and the iss turns into legacy of mankind 3) "space elevator" has physical boundaries.

(*)I'd invest in long term scientific research that will solve our overall space exploration necessities rather than investing into a expensive engenieering puzzle that will cost whatever agency that gets this project on table a motherfucking load of job (j) and money that will be used only for 20~ years if you ask me.

>tl;dr
Space elevator = short term costly (not only in monetary resources, but in time and engenieering effort) disposable technology.

>> No.7143448

Is space elevator /sci/ bait or I have to accept that /sci/entists are a bunch of delusional faggots?

>> No.7144457
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7144457

>>7142755
>>7142757

>> No.7144468
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7144468

>delusional faggots?
or maybe just disneyfied enthusiasts? let's see:

(a) At which height can a fan drop a rock from the space elevator such that it stays in orbit?

(b) Using the space elevator, outline the orbital scenario required to supply the ISS and to replace a GPS satellite.

>> No.7144516

>>7143244
>Neither do modern designs, using carbon-nanotube ribbons.
Oh, fuck off. Tapering is an absolutely standard feature of modern space elevator concepts. It was suggested a while after carbon-nanotube became the standard building material.

If you're not including tapering in your design, you're setting up a strawman.

>> No.7144544

>>7144468
>supply the ISS
Is that a joke? The ISS is LEO air can of only symbolic significance. Even if we did do a space elevator, the ISS wouldn't still be around when it was ready, let alone be considered important after the space elevator was completed.

>Using the space elevator, outline the orbital scenario
Orbital maneuvering is far, far easier than launching from the Earth's surface to orbit (it requires only small maneuvering thrusters and enough propellant), so if you can move material cheaply to a high orbit, you can get it down to any lower orbit you like pretty easily.

There are plenty of rational objections to the space elevator, but this isn't one of them.

>> No.7144551

once they can produce massive amounts of graphene and turn it into cables.

you'll also need to move an asteroid into orbit to serve as an anchor.

any nation that has a space elevator has access to huge amounts of power and material resources.

>> No.7144583

>>7144551
You've got your concepts mixed up.

One idea is to grab a carbonaceous asteroid, move it to GEO, and manufacture CNT cable from it to build a space elevator. This idea is based on the assumption that we're not any good at launching stuff without a cable, so we need to launch some crazy high-tech gizmo.

The asteroid "counterweight" isn't necessary, it's just left there as a side-benefit of the process, to serve as raw material for further expansion.

Another idea is to manufacture the cable material on Earth, and send up some minimal ribbon in a single launch, then use that to lift more ribbons to thicken it into a cable strong enough to take a useful payload. No asteroid involved.

You need some mass above the GEO altitude, but it's not more than the mass of the cable up to GEO itself.

>> No.7144649

This is stupid and not necessary, yeah im stupid too.

>> No.7145267
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7145267

>>7142924

>elevator is built off the east coast
>space debris puts a hole several thousand miles up
>thing comes crashing down, leaving a trail of debris west of the site
>your house gets a massive, flaming, carbon girder on top of it
>mfw

>> No.7145275

>>7145267
we put it in Texas. So that if it falls, it falls on Mexico.

also you can avoid impacts with a powerful laser system out in space altitudes. Lasers burn objects and the outgassing pushes them away.

>> No.7145455

>>7142886
My dick

>> No.7145563

>>7145455
I think nanotube technology is limited to carbon at this point.

>> No.7145566
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7145566

>>7145563

>> No.7145593

>>7145563
Actually, boron-nitride nanotubes are also very interesting, having comparable mechanical strength but being more stable and being electrical insulators.

Then there's silicon nanotubes, and these:
https://en.wikipedia.org/wiki/Inorganic_nanotube

And of course, there are membrane nanotubes, which can extend for up to 100 micrometers from an animal cell, and you see, I wasn't off topic at all.

>> No.7145656

>Is it possible?
Probably in the near future.
>Will it be done?
Only if some company figures out how to make a bunch of money off of it.

>> No.7145816

>>7145563

I aint no big city scientist but isnt penis carbon?

>> No.7145842

>>7145816
Roughly 15% to 20% carbon.

>> No.7145971

>>7142282
the most stupid thing possibly

>> No.7146013

>>7142282
assuming a material strong enough i suppose so

it wouldn't be rigid and would have to have something applying force to keep it from falling down

>> No.7146020

>>7146013
as a sidenote it would also be highly impracticle due to satellites and other debris floating about up there

>> No.7146039
File: 72 KB, 300x517, Space_elevator_structural_diagram.png [View same] [iqdb] [saucenao] [google]
7146039

>>7146013
>>7146020
Most designs for a space elevator include a counterweight that would prevent the elevator from collapsing under its own weight.
Many designs are also built on an ocean platform that would be able to move itself out of the way of any debris floating in orbit.
I suppose it could also move out of the way of satellites, however there aren't enough in orbit to be a very big issue.

>> No.7146070

>>7146039
a counterweight of that mass would fuck up a lot of shit

it would be less destructive to use propulsion (eg electromagnetic force) to keep it up

>> No.7146076

>>7146070
actually i was assuming the elevator would be heavy

i suppose it wouldn't have to be that heavy assuming the elevator was light

>> No.7146160

>>7142886
Arch Enemy

>> No.7146671

>>7145563
noice

>> No.7147090

>>7146070
That diagram is drawn no where near to scale. The elevator wouldn't even be visible that far from earth.

>> No.7148570

>HOTEL COUNTERWEIGHT

...where up is down and down is up

calculate the value of g for a geostat orbit of 53e6 m above surface

>> No.7148778

"What if" (book) talked about this and the physics of material tensile don't work out.

>> No.7148797

>>7144516
>If you're not including tapering in your design, you're setting up a strawman.

Then show me a tapering design where I can perform calculations on it.

>> No.7148801

>>7148778
What if talked about airplanes in 1800, doesn't work out.