Space Elevator | 100,000 KM | VISION

[Trantor]

exactly. Basically, you could launch all the material for the space station (MUCH LARGER ONES) via the Space Elevator, for a cust 100x smaller than today, and then launch people with other means.


Note that many of these other systems, like that spaceplane above, only really serve for people, they cant carry much cargo. So to assemble in space a big VASIMR/Polywell ship to take people to Mars and beyond, with material to build a base, enough supplies, several modules to land and get into orbit, etc... you need a CHEAP way to transport all that into space... and you would need hundreds or THOUSANDS of space planes flights to get all that into orbit...

[The North One]

i just thought of this but governors island in new york would be THE perfect place for a space elevator.

[The North One]

Originally Posted by JDRCRASH

^
Note "Economically feasible". A project like this WILL run into the Trillions of dollars, perhaps Tens of Trillions.

it would only take about 10 billion

[donoteat]

Originally Posted by The North One

i just thought of this but governors island in new york would be THE perfect place for a space elevator.

When did Governer's Island move to the equator?

[Bootstrap Bill]

Originally Posted by The North One

it would only take about 10 billion

We would need more than one space elevator. I read somewhere (wish I could remember...) that a trip on the space elevator would take nearly a week and that only one elevator car could travel at a time. This would severely limit how much we could put into orbit.

I'll bet a trip to orbit will still cost nearly $1 million.

[Trantor]

Originally Posted by Bootstrap Bill

We would need more than one space elevator. I read somewhere (wish I could remember...) that a trip on the space elevator would take nearly a week and that only one elevator car could travel at a time. This would severely limit how much we could put into orbit.

I'll bet a trip to orbit will still cost nearly $1 million.

that would be already 20 times cheaper than chemical rockets. But anyway, after a initial ribbon is deployed, its easy to expand it.

[The North One]

Originally Posted by donoteat

When did Governer's Island move to the equator?

im just saying it would be a cool spot

but it wont happen there, silly me

[Alpha]

A space elevator is a very interesting project. But what would happen, if the structure would be destroyed in the middle for example by a meteor?

[JDRCRASH]

Thats very unlikely, but if it did, I'd imagine it would be difficult to repair.

[Alpha]

Not only this. The lowest part may come down and perhaps wind around the equator of earth if it survives atmospheric entry.

[Trantor]

Originally Posted by Alpha

A space elevator is a very interesting project. But what would happen, if the structure would be destroyed in the middle for example by a meteor?

The upper part would be thrown away from Earth, while the bottom half would fall down and wind up around the equator... but the density of the nanotube cable is so low that nothing really would happen, and its possible that the cable would melt at reentry.

[ardecila]

Originally Posted by Trantor

If broken, it would fall to the Earth with the speed of a feather, after entering in contact with the atmosphere.

Who's talking silly science now? Haven't you ever heard that question about which falls faster: the pound of feathers of the pound of bricks?

Feathers fall slowly because their shape resists the air pressure with enough frictional force to counter-act the limited gravitational force that acts on such a light-weight object, so it reaches a terminal velocity VERY quickly. If you were to place a pound of feathers into a weightless box and deprive the feathers of the benefits of their shape, that box would fall just as fast as if that box had a pound of bricks inside it.

The carbon nanotube, I imagine, would be round or hexagonal in section and provide absolutely no air resistance, so it would fall pretty quickly, with the severed end falling faster than points closer to the earthbound end. Since it's so small, it may burn up in the atmosphere, but maybe not. I don't know about the heat resistance of carbon nanotubes, but the heat-protective ceramic tiles on the Space Shuttle are made of carbon compounds, so the nanotube may survive the descent.

[Trantor]

Originally Posted by ardecila

Who's talking silly science now?

you

Haven't you ever heard that question about which falls faster: the pound of feathers of the pound of bricks?

if you compact both enough, they will probably fall at the same speed. If you make a rope of feathers, it will probably fall slower.

Feathers fall slowly because their shape resists the air pressure with enough frictional force to counter-act the limited gravitational force that acts on such a light-weight object

limited gravitational force?

so it reaches a terminal velocity VERY quickly. If you were to place a pound of feathers into a weightless box and deprive the feathers of the benefits of their shape, that box would fall just as fast as if that box had a pound of bricks inside it.

o rly?

anyway, if you add enough feathers inside a weightless box, and make the inside of the box with VACUUM, the box will rise up in the sky, just like an helium baloon (you usually cant do that because if the object is light enough, its usually also very easy for surround air pressure to crush it... if it can support the air pressure, then it will be a heavy object made of metal probably. (thats why baloons are made of low density gases, that can provide pressure from inside... in theory, a vacuum baloon would be more efficient going up)

The carbon nanotube, I imagine, would be round or hexagonal in section

WRONG

the proposed space elevators are all RIBBONS, that is, they would suffer a lot of air resistance.

and provide absolutely no air resistance

as I said, not only it would be ribbon shaped, but also take a cord (cordon?) like lets say these ones that are used for kites. Whats the shape of such a cord? ROUND.

Now, throw it from the top of a building, along with a brick. You will see that they WONT FALL at the same speed.

Originally Posted by Wikipedia

If the break occurred at higher altitude, up to about 25,000 km, the lower portion of the elevator would descend to Earth and drape itself along the equator west of the anchor point, while the now unbalanced upper portion would rise to a higher orbit. Some authors (such as science fiction writers David Gerrold in Jumping off the Planet, Kim Stanley Robinson in Red Mars) have suggested that such a failure would be catastrophic, with the thousands of kilometers of falling cable creating a swath of meteoric destruction along the planet's surface; however, in most cable designs, the upper portion of any cable that fell to Earth would burn up in the atmosphere. Additionally, because proposed initial cables have very low mass (roughly 1 kg per kilometer) and are flat, the bottom portion would likely settle to Earth with less force than a sheet of paper due to air resistance on the way down.

if you had any doubt, you can discuss it at www.liftport.com/forums/

[M II A II R II K]

Space elevator team wins $900,000 from NASA


Nov . 7, 2009

By Clara Moskowitz

http://www.msnbc.msn.com/id/33737313...science-space/

A Seattle-based team has won $900,000 in this year's Space Elevator Games, a NASA-sponsored contest to build machines powered by laser beams that can climb a cable in the sky.

- The homemade cable-climber built by the LaserMotive team climbed a 3,000-foot (900-meter) tether suspended by a helicopter at a speed of 8 mph (3.7 meters per second or 13 kilometers per hour) during a Wednesday attempt.

- LaserMotive's robot climber managed to get all the way up the cable four times in two days, with a best time of about 3 minutes and 48 seconds (translating to a speed of 3.9 meters per second).

[Horizon in air]

Originally Posted by Trantor

if you compact both enough, they will probably fall at the same speed. If you make a rope of feathers, it will probably fall slower.

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From where it's most likely to snap (The section with max tension a.k.a roughly GEO height) you fall almost 36000 kilometers in vacuum since 99.9% of the entire length is in space. During th fall, F = GMm/r^2 which adds up to a hell lot of potential energy if you do the math. The fact is most of the ribbon would instantly burn up upon contact with the thicker atmosphere.

Originally Posted by Trantor

o rly?

anyway, if you add enough feathers inside a weightless box, and make the inside of the box with VACUUM, the box will rise up in the sky, just like an helium baloon (you usually cant do that because if the object is light enough, its usually also very easy for surround air pressure to crush it... if it can support the air pressure, then it will be a heavy object made of metal probably. (thats why baloons are made of low density gases, that can provide pressure from inside... in theory, a vacuum baloon would be more efficient going up)

Totally missing the point here. Everything accelerates at the same rate in vacuum under the same gravitational field. What he's trying to imply is that is that if you take out the factor of aerodynamic drag (which can indeed be neglected in space), both the feathers and bricks would fall at roughly the same rate.

Although I must say that even with the same aerodynamic profile, the terminal velocity of the feathers would be much lower in the atmosphere.

[Trantor]

Originally Posted by Horizon in air

Totally missing the point here. Everything accelerates at the same rate in vacuum under the same gravitational field. What he's trying to imply is that is that if you take out the factor of aerodynamic drag (which can indeed be neglected in space), both the feathers and bricks would fall at roughly the same rate.

"The majority, the long end out in space, gains enough speed that it burns up in the atmosphere, with the lower portion falling into the sea. It will not fall on top of anyone.

It would be more accurate to say that the lower portion flutters rather than falls down. This is because it is extremely thin, much like plastic wrap or newsprint."

For the portion that doesn't burn up - what effect will it have on the environment?
"Honestly, it will make a little bit of a mess. But New York City tickertape parades have made bigger messes. Comparatively it will put much less dust, dirt, debris and chemicals into the environment than wildfires of the American west, any one of the large expendable rockets, or a month of natural meteors hitting Earth. The ribbon is light (7.5 kg/km) so, any pieces that fall to earth will slow down, in the air, to about the same terminal velocity as that of an open newspaper page falling. It will not have enough momentum to cause mechanical damage when it comes down. We have considered other health risks such as inhalation of very small fragments and believe this will not be a problem but we are conducting studies to make sure this isn't a problem. Since we are aware of the possible problems now we can design the elevator to avoid these problems."

[ChicagoChicago]

Well, I finally got around to watching StarTrek last night. The "drill" that lowers into the sky from space got me thinking. What would happen if a spaceship were to lower a cable from space. Assuming it is in a geostationary orbit, what would happen to the object? Obviously, as it got closer to earth, the cable would experience stronger gravity...but what effect would that have on the ship?

[Bootstrap Bill]

Can a space elevator make access to orbit affordable by the average "middle class" person?

If not, is there anything on the horizon that could possibly accomplish this?

[Trantor]

Originally Posted by Bootstrap Bill

Can a space elevator make access to orbit affordable by the average "middle class" person?

not at principle. For some reasons

1 - its a 33 thousand kilometer trip (more or less depending if you are using a counterbalance)

2 - at speeds of what... 250km/h?

3 - passing through the Van Allen belt! The Apollo ships passed through it in less than an hour... thus the total radiation dose was no more than the astronauts would receive from a chest xray plate.

4 - the space elevator was actually thought for putting massive amounts of cargo into space... it would make possible to mount massive space stations, massive moon bases, massive ships (think ships the size of aircraft carriers), etc, etc.



Of course, the question of humans using space elevators thus reside in a few things:

1 - the speed of the space elevator "cars"

2 - how shielded they are, and how confortable they are to support humans in such a long trip.

[village person]

This sounds really cool, but I'm currently struggling with the very idea that mankind's betterment lies in space exploration. And even considering that idea, it's hard to get too excited over anything going into that exploration in my lifetime, when right now it's a bit like knowing there must be an inhabitable acre or two of land somewhere across that unexplored ocean, yet all we can do right now is draw really expensive figures of paper canoes in the sand.