robots necessary for multi-kilometer tower

Here's a shocking fact: NASA thinks that multi-kilometer towers would be really cool. One, they could use the heat differences in a 15-kilometer tower to drive a heat engine and make lots of "free" electricity, and two, they could use it to reduce the cost per kilogram of space launches.

You can read NASA's story at:

http://flightprojects.msfc.nasa.gov/pdf_files/usrp.pdf

http://216.239.41.104/search?q=cach...pdf multi kilometer tower NASA&hl=en&ie=UTF-8


I read this and I thought, "Wow! This is great! No need for kooky, probably impossible stuff like anti-grav or cold fusion! This is the Holy Grail! We need to build this right now!"

Now there's one small catch. There's one tiny little technology in NASA's plan that is not ready for prime time.

That is automated construction.

NASA has materials that are light enough and strong enough to support a 50-kilometer-high tower. That's not the problem. The problem is that building a tower that high would probably require "automated construction." I.e. they want robots to do the actual assembly so that they don't have to put pressure-suits on union carpenters and welders. (Think about the life insurance premiums you would have to pay to work at 2 kilometers above earth's surface...)

And unfortunately, I don't think that's going to be possible any time soon. The latest robotics advances I have noticed are: one, the U.S. has great unmanned war drones, and two, the Japanese have walking robots that should prove handy in a few years when all the Japanese are in nursing homes and need exoskeletons to walk. Beyond that, I haven't noticed anything revolutionary coming out in the robotics world that looks like it could be smart enough to build a tower.

Now, if we had a robot construction machine that could build *any* tower, it could be improved to where it could build a multi-kilometer tower.

I have done some Google searches, and come up with very few documents to indicate working technologies.

http://fire.nist.gov/bfrlpubs/build02/art105.html
is a link to "contour crafting," which seems inadequate to the multi-kilometer tower task.

I would *love* to be proven wrong. I would *love* to find that automated building construction is rolling out, or just around the corner. But unfortunately it looks like decades of advances will be necessary before robots can construct towers.

 

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sorry, forgot a link

http://www.ri.cmu.edu/~isarc/program_pages/bldgConst.html

the above link is not terribly informative, but it offers some interesting ideas, such as the Japanese method of building the top floor first, pushing it upward on jacks, and then building the next-highest floor below it.

Unfortunately, it's hard for me to estimate how far all these technologies are from the goal of building a multi-kilometer tower...

 

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15kms? Whaddahell...... first off, it t doesn't consume enough land area I'll say it will not stand, but okay, if the tower's too wide, it may collapse as well....
Call me psimistic, but I just can't get it......

Oh, riprock, welcome to sciforums..... sorry if I welcome you with bad reply.

 

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I didn't read those articles, but I believe they would be using carbon nanotubes to build the tower. I read something very similar in a book called "Nanocosm" (VERY good book btw).

In which case, yes, a tower 50km tall would be possible-- almost regardless of how big it's base was.

 

Towers could be useful for power generation, as turbines inside catch the hot air rising from the base; so these things sound cool in many ways. (especially towards the top)...

However they have some drawbacks- they would be very heavy, so might affect the bedrock below drastically- you couldn't just throw them up anywhere.
Also to launch a satellite from the top might be difficult, as the acceleration to orbital speed required is nearly the same as that required from ground level.
The most significant reduction is atmospheric drag.

Now to accelerate using a mass-driver you would need an inclined plane, or similar curve- which would make this tower into a ramp several tens of kilometers long...
still, it could represent a lot of high rise living space in such a large structure...
yes, why not go for it, the engineering problems should be easier to solve than those associated with a space elevator.

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Wouldn't it be much cheaper to attach a large platform to 4 Hindenburg sized blimps ?
these blimps could get to 25-30 km height.

 

50km...seriously? I am thinking it would put a hamper on the supplies since unheard of amounts of construction material would be needed. Hell the iron supply is predicted to be stressed during the construction of the Millenium towers in Japan (Not sure on the name) and they are a fraction of the height compared to this.

 

In Cyber City Oedo they kept their really tall buildings standing with the help of gyroscopes, so the tower wouldn't need to be particularly thick to remain straight - on the other hand, the weight might be a problem.

 

I don't understand why the air inside the tower would rise. Why is the air insde the tower any more likely to rise than the air outside the tower?

 

The power generating tower designs I have seen have a large base, which draws air in for a large distance around; the base is dark coloured, and absorbs solar heat, expanding the air inside, which rises;
there is no need for a power generating tower to be 50km tall, however.

One wacky sci-fi idea is to build towers which are supported by magnetic fields acting against a continuous stream of iron pellets; this is known as a space fountain (and s a net consumer of energy).

Although such an idea would possibly work it doesn't achieve much; you still have to accelerate very hard from the top of the tower to reach orbital speed (unlike a full length space elevator, which has a centre of gravity travelling at orbital speed - so is relatively easy to dock with.