/sci/ - Science & Math

it's rather hard to imagine a material that would have the tensile strength to hold an object tethered to the earth... and also preventing it from crashing down as well

>>3425460
carbon nanotubes

/thread

>>3425465
can't synthesize them in the required lengths, sadly

Graphene might work out, maybe

No, this is fucking bullshit.

best bet is probably to haul up a "lift line", a very very thin primary line not meant to bear much weight.

62,000 miles of it will weigh a fuckton. falcon 9 heavy is probably our best bet.

>>3425510
a fuckton is putting it lightly
the cable would need to weigh half a pound per mile. horry shit

does it need to be 62,000miles? I thought they were planning a 600mil long cable.

>>3425517
for a thin enough graphene type deal, half a pound a mile isn't that crazy actually.

lowering the thing through the atmosphere and connecting it without the entire thing breaking? little more difficult

>>3425593
from ground to counterweight, it needs to be 62,000 miles, unless there is some way to connect multiple small cables and not have the connections snap to pieces from the stress

>>3425595
no I'm saying that the destination of the elevator would only be 600 miles above the earth's surface.

>>3425595
and i heard it wouldn't need a counter weigh because the car would "crawl" up and down the cable rather than be hoisted.

why do we have to pull it up? Just start from top and lower it down.

>>3425606
the only way to keep the cable taught was by having the counterweight that far out
this is space elevator 101 folks come on

>>3425601
the geostationary point? yes, but that's at 22,000 miles up, not 600.

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

Space elevator will never happen. No materials are strong enough nor resilient enough for the extremes of temperature in space.

>>3425622
the centrifugal force of the earth's rotation should eliminate the need to go out that far. anyways my information is coming mostly from articles written in 2007 and a brief mention in a documentary about carbon nanotubes, but 600 miles, crawling up the cable, and centrifugal force were all things they mentioned as being on the side of feasibility.

>>3425631
except for space shuttles, right? Or satellites?

>>3425639
And Astronauts.

>>3425639
dude, this is a whole other ballpark
i've seen the torsion forces this thing would be under. it would make your mind fucking melt. asking it to do that as well as take solar radiation and direct sunlight/space cold is a little much

here's what always boggled my mind. so we got these nanotubes which have the weight to strength ratio needed to hold a space station to earth. OK fine, but what are they going to be connected to down on earth that's that strong? eventually this thing is going to be transferring energy to rock or dirt. so how is that being solved?

>>3425652
Counterweight.

Fuck high tensile strenght materials. There are space elevator concepts which do not require them:
http://en.wikipedia.org/wiki/Launch_loop

We could build the thing fucking NOW..

>>3425634
you're talking about the virtual space elevator
http://www.spacefuture.com/archive/space_elevators_space_hotels_and_space_tourism.shtml

the lowest point would be a 160mi up space dock that accepts sub-orbital payloads

>>3425660
>2000km long, 80km high maglev track
......
no

>>3425669
Why the fuck not? Too much engineering for you?

>>3425673

Well yes.

>>3425669
can we see fewer one word responses on /sci/?

>>3425700

ok

>>3425705

>>3425713

heh

The material needs to withstand 30 gigapascals, carbon nanotubes can withstand 63 gigapascals.

>2011
>weapons

faggots

Send a nanotube synthesising satellite into LEO to build 10KM stretches of tubes, replacing used carbon via rocket. Once there are 10,000 stretches, send up an X-37 unmanned space plane to boost the satellite into Geostationary HEO. Send up the counterweight station (Not necessarily the weight itself, but probably. Depending on the efficiency, harvesting moon rock might be more cost effective)
Assemble the tubes from the sky downwards, making sure the base station always stays within 200KM of geostationary. once enough cable has been assembled to balance the satellite at that point, fire it out a bit further and finish the cable. Keep the counterweight stable with chemical boosters, but allow conversion to VASIMR in the future.

>>3425730
wait, it was only 30? i thought it was 100+

Why use matter at all?

>>3425769
it tends to be quite reliable.

>>3425769
Antimatter space elevators tend to be bad for the passengers.

>>3425774
Not for the distances we need.

>>3425775
LOL! You're so kawaii! <3

>>3425779
That's why we're suggesting nanotubes, and how was that kawaii?

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

How about this? Also why you no talk about mass drivers /sci/?

but that's gay

>>3425746
this is assuming you can synthesize the nanotube strand on the fly
which, if you use organic assembly techniques, might not be that crazy

>>3425831
I hope we can soon. The ability to do it would be quite literally revolutionary

>>3425833
assemble carbon nanotubes with organic assembly techniques?
M.I.T has been doing that for a few years, in addition to batteries and solar panels

the trick is ACTIVE assembly, in large volumes, but that's probably not quite so tricky

>>3425835
That's awesome. I was referring to the on the fly bit, but having the ability to assemble them without using tiny tweezers is a definite plus.

>>3425838
http://www.solarnovus.com/index.php?option=com_content&view=article&id=2690:mit-researchers-
use-virus-templated-nanotubes-to-improve-solar-efficiency&catid=52:applications-tech-research&am
p;Itemid=247

program a virus just right and it'll pretty much suck your dick and give you money

Space elevators are going to be a pain. It's al well and good waving around carbon nanotubes, bt you can't just make a shaft of solid carbon 22,000 km high. It's going to need to be coated in something to protect from micrometeorites/ the atmosphere. It's going to need stations along it's length keeping an eye on it. It's going to need lights near the bottom so planes don't crash into it at night, and a lick of paint so they don't do the same during the day. All this stuff's going to add up.

My personal preference? Build a few launch loops. Use these to catapult huge amounts of iron into LEO, or fire some tugs into space to pull some iron rich asteroids down into LEO. Assemble all this iron into a huge ring and spin the ring slightly faster than the orbit speed. You can then build a few stations along the ring, make them run around it so they keep station with the ground below them, then drop a few cables down to the surface. The cables are only a few hundred miles long so they don't need to be made of something we can't make yet.

>>3425848
so
a giant ring of iron circumnavigating the earth is less of a pain than a carbon nanotube space elevator cable?

>>3425843
That is pretty fucking amazing. I had no idea we were actually doing this kind of thing.

>>3425843
that's kind of baby steps stuff, the virus only acts as a scaffold that the carbon nanotubes attach to. true organic self assembly is still some ways off

>>3425849

Considering it's made of stuff we can actually manufacture in lengths greater than a few millimeters, yes.

>mfw the carbon nanotube producing genetically modified bacteria evolve into gray goo

>>3425858
>mfw natural selection also works for the goo
>goo becomes multinodal
>develops intelligence
>inadvertently becomes superintelligent AI

Make a big ladder out of nanotubes :)

>>3425876
>rest hand on rung
>thin enough to cut through hand
>severs fingers

>>3425884
>sets out to climb huge ladder into space
>doesn't wear gloves

Ladies and Gentlement, tripfags.

>>3425896
>has 10 nanometre thick blade proof gloves
DO WANT

Hang rope from south pole. Make it like, a billion miles long. :)

weave the cable from the sinew of godless foreigners

>>3425884
>>3425896
>>3425898

>Where are my nano-wire saws

>>3425981
in a lab at MIT probably.

Very long rail-guns? That accelerate at 9.8ms^2?

>>3425993
why that speed exactly?
Not sure why you'd need -1g

>>3425884

>Re-attach fingers
>Try again

DO YOU ALWAYS SURRENDER SO EASILY

>>3426007
I DID DO THAT HOW ELSE WOULD I KNOW
*sigh*

>>3426002
To comfortably get humans into space. A short rail-gun would accelerate 0 - 5000ms^-1 in an instant, killing everyone.

>>3426333
Humans can take about 5G without passing out and making it that slow would force you to build it to extend hundreds of kilometres into space.

Every point except the endpoints would be subject to considerable tidal stress.

I very much doubt this is within the range of our current technology, other than with (maybe) nano-constructed diamond or similar materials.

If you're using nano-assemblers anyway, then just program the little bastards to build it up until they get to orbit. They'd also have to construct feedlines for the carbon as they go, and whatnot, but that's trivial compared to the challenge of building the nano constructors in the first place.

>>3426343
Picking over details somewhat there, though I concede defeat. I used 9.8ms^-2 as an arbitrary safe acceleration.

There'd be no need to extend it upwards though, surely you could reach escape velocity on a linear (in line with the Earth's curvature) rail. Very easy, relatively cheap.

>>3426362
I schpose. You'd have a huge footprint, though.

>>3426353
apparently the max tension on a space elevator cable is 30 gigapascals. currently manufactured carbon nanotubes can take 63, and theoretically can take 300

the problem would be getting the seed cable up there, if it's on the falcon 9 heavy, the cable would need to weigh less than half a pound per MILE of cable.

which is where synthesizers come in; which is where things get tricky

>>3426362
You could, but it would probably be more useful for launching cargo than humans, due to the accelerations involved.

http://www.youtube.com/watch?v=9Aq485-WwF4&t=36m10s

>>3426411
same anon here

vid unrelated

>>3426362

The problem is going close to escape velocity in the atmosphere will cause most things to burn up pretty quickly. Ideally you want to build it up in the sky, in which case you might as well create a launch loop.