elevator to space?

[Jason]

any thoughts on this. Being able to have an elevator that will reach space using technology that is pretty recent in it discovery to transfer many tons of material up to the heavons...thoughts?
heres a link to more info http://www.space.com/businesstechnology/technology/space_elevator_020327-1.html


Jason

[oracleguy]

There was some star trek episode where they go to a planet that had one. :)

[Roy Sinclair]

See http://www.spaceelevator.com/

[Jason]

I will soon be ably to say "beam me up scotty" and my destination will be space :thumbsup: just will have to worry about getting down....


Jason

[bcarl314]

Hmm, with all the space junk circling our planet, I think this is not only a bad idea, but also pretty stupid. And I don't use stupid too often!

Ok, so we build this elevator to space. Where are we going once we get to the top?

The trip is over 21,000 miles? How long will that take? Lets say we go up and accelerate a -1g so we feel 2g on our body for the trip. At best that's an hour ride, assuming you can accelerate for the entire duration, but you can't because you'd be traveling at about 13 miles / second when you reach the top. Just a weee bit too fast to stop quickly. (Assuming my math is correct v=at & d =(at^2)/2)

Ok, so lets say we're ok with a 5 hour trip to the stars. Now, what happens when a piece of space junk (something left over from an Apollo mission, or sputnik) happens to hit our elevator and cut it into 2. You'd either go flying into space or fall thousands of mile back to earth.

Not a good idea any way you look at it.

We should stop wasting money on projects like this and spend some real money developing far more reliabe (and proven) launch methods!

[liorean]

Well, the major idea with a space elevator is that you don't have to transport the fuel or the overly large rockets, but that you can do a simple trade of energy worth about the same as moving the thing you're carrying for the distance. Thus, it's an enourmous save of energy to have a space elevator. And the space elevator cable itself would probably not be that fragile - the capsule you're moving up it would be the part that might get seriously hurt from space debris, along with the station on the other end of it.

[Roy Sinclair]

Re: Space junk.

A large part of the problem with space junk right now is that it's leftover parts from current and older launch technologies. We could actually send missions to retrieve that junk but the cost of putting something into orbit is very high. However, an elevator would reduct the cost of reaching orbit enough to make it cost effective to clean up the junk. As long as we continue using disposable rockets at several million dollar per launch the idea of catching and disposing of that junk (or in some cases retrieving it for museum display) will remain unfeasable.

[bcarl314]

I don't understand how we capture energy savings. We would still need to lift a capsule (500 kg??) with people (200 kg) up 20,000 + miles. We would need to expend the same amount of energy if not more because, before we pass the geosynchronus (sp?) point, we would be fighting against gravity going up, once we pass that point we're fiting centrifugal forces to slow down.

With a normal rocket launch, you're not expending energy for 20,00+ miles. You only need to get up about 15 - 20 miles before you can stop using fuel generated energy, and use gravity (slingshot effect) to get to a higher orbit gradually.

Of course, it takes a few days to get to a higher orbit. But the point of a elevator (for commercial and tourist purposes) requires faster travel times and thus, we can't wait days to go up to the top.

[Roy Sinclair]

Try reading some of the articles at the reference I gave above, they go into great detail about how the elevator would work and what sort of energy is required.

[bradyj]

The Discovery Channel recently did a show about this -- how they would use Carbon (pardon, I don't remember the specific term) compounds that would build a tether strong enough and light enough to elevator that far. However, we don't have the funding or material to get it -- and I remember that their large complaint (other than space junk) was the fact that it would have to be fitted with some type of boosters at the top... much like the space station, every now and then you need to big 'shot' a little higher up, as over time to tend to veer closer in orbit, and dangerous to being sucked down.

I'm all for it, I'll ride it first:) I love seeing advancements in space and technology, it seems to be so quite in our interests, but it has to be the future one way or the other. Whether it works or not, atleast worth the knowledge of giving it a go.

[liorean]

Well, not only do we have a whole new set of energy sources for the space elevator (magnetism, friction, electricity), we have a new stable structure to work from (the cable) and we have the fact that one doesn't need to achieve the same acceleration as for the ballistic rocket, and accelleration, not speed, is the real energy expense. That goes for accelleration in both directions, of course, relative to a normally stable set of environmental conditions (gravity, centrifugal power, cerntripetal power). These environmental conditions will change during the transit, but not so much that the stable structure (the cable) can't be used to counter the change.

[bcarl314]

All I'm saying is that we can better use our resources on other projects. Such as developing cost efficient, powerfull proton rockets for inter-planetary travel.

Pursuing the "space elevator" which has a fixed path and limits to functionality is alot like developing a steam locomotive when you've already got airplanes.

The argument could be made that you still need an efficient way to get people into space in the first place, before they board a space ship, and while this is true, enhacing porgrams like the space shuttle and space plane will go much further, much faster than the space elevator.

[liorean]

Hmm, I'm not sure I agree here. Let's make a biology analogy. Do you know that a cell spends a lot of energy creating a steep concentration difference (or gradient, if you prefer that terminology) of Na+ on the outside from the inside? This is a difference that the cell continually have to pump Na+ out to keep. Then, the cell uses this same difference to get things into the cell, allowing small amounts of Na+ to get back inside (which would happen randomly anyway, but much slower), but use the energy that is deposited in that difference to bring glucose in with it as well? This is a good example of what a space elevator allows - it allows using an expensive structure to radically reduce a continuous expense. (This case is what allows us to absorb glucose in the intestines, if you wanted to know. In other places in the body, this kind of mechanism isn't needed, since the concentration gradient works towards the goal, not away from it.)

What this means, is that creating a spaceship from parts in space, plus the cost of bringing them up into space, and then launching that spaceship from the elevator station, is much, much cheaper than creating the same ship down here, and then launching it from here. The space elevator is a large cost, but it's essentially something that reduces the running costs and thus it's well worth the expense.

(Does my being a medical student show?)

[bcarl314]

Hmm, biology. I would have never guessed! :D

[Nightfire]

:confused: Too advanced for me

:p I'll go in the elevator anyday, press the top floor button and away I go

[Jason]

I don't know but I read in the paper yesterday about this stuff, hence I put it on here, but the cost difference is something like this: right now it costs like $10,000 per pound to $100 per pound. And I don't know about you, but I don't got no $1,600,000 to get my little butt into space, I would much rather pay $16,000 to go into space. Also, one thing about the space elevator is that its only purpose is to move things into space, there is no comming back using it. Also the fibers for it are so strong and thin that it would be like a ribon 3 feet wide and thinner than paper and be able to haul hundreds of tons. This ribon is stronger than steel, the only thing is the longest one created so far is only a few feet long so making one 32,000feet to get it long enough to get it into orbit will take some time...


Jason

[liorean]

Nobody has mentioned this yet, but you could use a small cable to haul up a larger cable, which you then use to haul up the final cable. The station could be placed there long before the cable was put in place, and then you could actually work from up there instead of from down here. That way, you'd actually be hauling down the cable, saving you the problem of the cable not being strong enough to lift the next cable through the entire distance. (It'd be far more costly to get the cables up there in the first place, however. But the thing would be easier to solve that way, which may compensate the cost.)

[Jason]

from the plan I read the cable will be made and then stretched to space. Onece that is completed it will be fastend down here on earth as well as in space. Next, a machine will ride the cable up and strengthen it all the way to the top with more/extra cable. I think thats about the extent of my knoldege on that area...

Jason

[liorean]

Well, building on the cable is about the equivalent of hauling up a new one. What I wanted to get at, was that it's so much easier if you begin from space, where gravitation will be to your benefit instead of having to work against it. Correcting the position of the station through thrusters would stabilise it enough to work.

[bcarl314]

Originally posted by Jason
the only thing is the longest one created so far is only a few feet long so making one 32,000feet to get it long enough to get it into orbit will take some time...


Jason

I think you meant to say 32,000 miles, as the geosynchronus point is about 21,000 miles and the elevator would have to go betonw that point to support itself.

Only of by a factor of 5280 ;)

[Jason]

oops, see what happens when the mind wonders....yeah, I meant miles...


Jason

[liorean]

32k would almost be correct, if you were counting kilometres...