Space Elevators

[Aberforth]

First I'd like to encourage everyone to post here. At the present time we are very close to building a space elevator, scientists in Japan claim that they could build it for 9bn usd if every problem around it is resolved. The biggest problem is the elevator cable- it has to be long and it has to hold it's own weight or it would break, it has to be 180 times stronger than steel wire- which is only possible with carbon nanotubes, according to wiki it costs about $25/gram and you would require about 18,000 kilograms of it to make a perfect cables. But there are other issues surrounding it as well..Anyway, here's something to discuss

-Whats your take on the progress being made in this area?

-What is your concept of going into space without rockets? Post diagrams if necessary (this should be fun)

-Do you have an alternative to the cable based elevator?

-Will it encourage space tourism? What about economy?

- If this is a bad idea, tell us- why?

 

[Modelworks]

I don't see it happening anytime in the next 20 years or so. If the cable breaks you have a very heavy cable coming down on populated areas at mach speeds. Also would require huge counterweights on the ground .

One system I saw for launching into space was using magnetism. Something like a rail gun pointed up.
http://nextbigfuture.com/2008/...-for-space-launch.html

I think the only thing that will make space really viable will be when we can manufacture in space itself, maybe something like a manufacturing facility on the moon. Lifting payloads through gravity and atmosphere really adds a lot of unnecessary cost that a craft built in space would not need. One of the biggest problems with designing probes and satellites now is the weight issues. If we could circumvent that , it would change things a lot.

 

[Aberforth]

Lunar base is an expensive idea, it would be in trillions. A small space station like ISS would cost about $240 bn, imagine lunar bases.

What we have do is come with an cable alternative...like the rail gun you mentioned. This is just an idea but why can't we use vaccum rods as rails for elevators? the vacuum pressure would act as a counter weight, take a hollow steel rod alloyed with titanium, add about 6 pipes within it to send air and the center pipe would act as an extender for the second rod, pressure can be controlled from the ground...Can we do that?

 

[f95toli]

Originally posted by: Aberforth


What we have do is come with an cable alternative...like the rail gun you mentioned. This is just an idea but why can't we use vaccum rods as rails for elevators? the vacuum pressure would act as a counter weight, take a hollow steel rod alloyed with titanium, add about 6 pipes within it to send air and the center pipe would act as an extender for the second rod, pressure can be controlled from the ground...Can we do that?

No, because the strength-to-weight ratio is nowhere near high enough for steel (or any other known metal). In order to build a structure that could reach orbit using metal it would need to be shaped like pyramid/cone and the base would have to be enourmous (I have no idea how big, but presumably at least a few hundred km or so in each direction).
Even if there was that much metal around I suspect the ground it was standing on would collapse.

The only known material that MIGHT work is a (very thick) "rope" made from carbon nanotubes, although the problem is that it is very difficult to grow nanotubes longer than a few tenths of microns. No one known is this could ever be scaled up to what would be required for an elevator.

 

[silverpig]

Actually none of the info in this thread is really correct so far. I was part of a team that competed in the nasa space elevator challenge and did a lot of research on the tech.

First, the thickest part of the cable is at the midpoint. The cable is actually in orbit around earth as its center of mass is at geosynchronous orbit. The cable orbits the earth and has to hold up the section dangling below, and hold down the part above. The tethering to earth is required to help rotate the cable along with it's revolution around earth. A steel cable with a diameter of about 1" at the surface of the earth would have to be several miles in diameter at geosynchronous orbit. Carbon nanotubes are a bit better, but the rope would still have to be several feet wide.

Nanotubes have reached lengths on the order of inches I believe, but it's a far cry away from a 100000km long tube.

Japan's claim that they could build one if all the problems were sorted out is the same as me claiming I could build a dyson sphere if all the problems associated with me building one had been worked out. It's kind of a tautology.

I'm pretty much convinced I won't see a space elevator in my lifetime.

 

[Andrew1990]

I think we should see one being built within the next 200 years. Not in our lifetime but close. I do believe we will have some sort of rail system described earlier.

A space elevator would be cool though, much more efficient that fuel based rockets in the long run.

 

[AstroGuardian]

I bet Chuck Norris could build a nanotube 100.000km long...... single-handed

 

[tommo123]

one thing that could bring it about more quickly i would think is if we had another space race. Afaik, aren't russia, china and europe putting more money into their space programs? a full on race to (something) would be cool right now. might even help with the current economic problems. IMO anyway.

 

[silverpig]

Originally posted by: tommo123
one thing that could bring it about more quickly i would think is if we had another space race. Afaik, aren't russia, china and europe putting more money into their space programs? a full on race to (something) would be cool right now. might even help with the current economic problems. IMO anyway.

China definitely is. India seems to be doing it as well.