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Siguy
2008-Oct-18, 11:11 PM
What would be the cost of a large rotating colony, such as an O'Neill cylinder or Stanford torus? Lets say we build an orbital mass driver, such as a Lofstrom Loop, which would cost from $10-50 billion, or we get the material from a metallic asteroid (whichever is cheaper). Let's also say that it's built from somewhere other than NASA or ESA, since they typically spend a lot more money than needed.

tdvance
2008-Oct-19, 12:57 AM
Got to be more than 50 billion, or else we'd have done it by now! And if not one of the major governments, then someone like Bill Gates.

Other than that, I have no idea the cost.

I would guess the cheapest way to make an O'Neil cylinder (which I would think should be called a Heinlein Cylinder, I think he got there before O'Neil) would be to hollow out an existing asteroid. Once we develop practical fusion, we'd even be able to give it life-sustaining power. I'm not sure what a Stanford Torus or Lofstrom Loop is.

Ronald Brak
2008-Oct-19, 01:25 AM
How much would it cost? A lot. The ISS cost about 235 million per cubic meter of living space. Although to be fair, Mir demonstrated that a space habitat can be built at a fraction of this price. So if we assume that lower cost methods in the future reduce the price by a factor of 1,000 from the ISS and there is 1,000 cublic meters of space per person, then a colony for 10,000 people would cost only $2 400 000 000 000 or $240 000 000 per person. Assuming 3% productivity growth, the average earning American could afford this with 10 years income in about 230 years. Mind you, if productivity increases dramatically this point could be reached much sooner. (About 40 years according to Kurzweil.)

Siguy
2008-Oct-19, 03:20 AM
Got to be more than 50 billion, or else we'd have done it by now! And if not one of the major governments, then someone like Bill Gates.

Other than that, I have no idea the cost.

I would guess the cheapest way to make an O'Neil cylinder (which I would think should be called a Heinlein Cylinder, I think he got there before O'Neil) would be to hollow out an existing asteroid. Once we develop practical fusion, we'd even be able to give it life-sustaining power. I'm not sure what a Stanford Torus or Lofstrom Loop is.

The Lofstrom Loop, or Launch Loop, is a giant electromagnetic accelerator track capable of launching payloads into low Earth orbit, for costs as low as $3/metric ton, which could be built with current technology and has been predicted to cost $10 billion for a low capacity, low efficiency model, and $30 billion for a high efficiency, high capacity model. I'm gonna assume that's a bit optimistic since those figures were put out by Lofstrom himself.

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

The Stanford torus is just a big toroidal space habitat. A really big one, not like those bike wheel ones from cheesy sci-fi films, and with an ecosystem, or at least grass and trees, not horrendously sterile gray plastic.

As for a hollowed out asteroid, I think this about sums it up.

Sometimes you just need space. And whether its for a colony, mining base, or interstellar spacecraft, what can beat a hollowed out asteroid? Sure, it means shifting tens of millions of tons of rock ( or worse, nickel/iron), adapting the interior for habitation, getting water and oxygen from somewhere, stabilising the spin of the thing so it doesn't precess all over the place, adding the thrusters just right to move it to the stars or a more convenient orbit (all this while wearing spacesuits, mind), and then hoping the whole thing doesn't leak, but you wouldn't want to go for the more difficult options, would you?
http://davidszondy.com/future/space/asteroid.htm

I think you could perhaps use little (possibly self replicating) autonomous robots to melt and cast bits of nickel/iron asteroids and gradually form them into a space habitat body, spaceship hull, or other big cylindrical object. Heck, this would be the way to go if you really, really wanted to make a full scale working replica of an Imperial Star destroyer.

samkent
2008-Oct-21, 01:32 AM
Here we go again!


or we get the material from a metallic asteroid (whichever is cheaper).
We donít have a space craft big enough and with a rocket powerful enough to investigate a prospective asteroid. Then tow it back to Earth and nudge it into orbit.

BUT NEVER MIND THAT DETAIL!

We donít have a space platform big enough and suitable for construction crews to live and maintain equipment while building this cylinder or torus.

BUT NEVER MIND THAT DETAIL!

Do you plan to give jack hammers to the crews to bust the asteroid into fist sized pieces of mixed metal? Or do you have some automated excavator in mind? It doesnít exist!

BUT NEVER MIND THAT DETAIL!
Now that you have mounds of mixed metal chunks stored in some fanciful container that doesnít exist. What about a smelter to melt these chunks into a homogeneous liquid of just the right metal while casting off the unwanted metals and such. Have you seen the size on comparable smelters on tv? We couldnít begin to launch something of that size!

BUT NEVER MIND THAT DETAIL!

What about the power needed to melt the ore? If you arenít aware most such places down here are located close to power plants due to the voracious power demand and terrible line loss involved. Can you imagine the size of the solar arrays you would have to launch to generate this power?

BUT NEVER MIND THAT DETAIL!

Now that you have the right molten metal shooting out you need something to turn it into sheets of the right size and shape. On Earth that requires huge machines and GRAVITY!

BUT NEVER MIND THAT DETAIL!

With the right shape metal you are going to need some fancy robots to weld and x-ray the seams in zero g. And making the struts and other internal supports in zero g. None of this exists.

BUT NEVER MIND THAT DETAIL!

Now you would have to launch all of the internal systems in pieces from Earth. Unless you want to launch manufacturing facilities to make pipe of all different sizes and shapes and materials. Pressure vessels, wire, insulation on and on and on. Donít forget the precision needed to make most of this stuff.

BUT NEVER MIND THAT DETAIL!

Hereís the bottom line.

If itís cheap enough to launch and man all of this non-existent manufacturing equipment into orbit itís cheaper and quicker to build it on Earth and launch it in sections. Plus it will provide more jobs.

So quit dreaming about manufacturing big things like that in space. Go back to dreaming about flapping your arms and flying. You stand a better chance of success.

Siguy
2008-Oct-21, 02:33 AM
Yeah, I figured that it would be difficult to manufacture in space, launching it in sections would be better. But then again, I'm not really talking from a practical standpoint. It could be done, we have the technology, but that doesn't mean it will be. But just imagine all the awesome things we could build if we had such an efficient system as a Launch Loop! I just don't see why nobody has built one yet.

PraedSt
2008-Oct-21, 02:34 AM
Here we go again!

It's just a little harmless fun Samkent :)
Mind you, I can see your point when this happens:


But just imagine all the awesome things we could build if we had such an efficient system as a Launch Loop! I just don't see why nobody has built one yet.


Lets say we build an orbital mass driver, such as a Lofstrom Loop, which would cost from $10-50 billion :rolleyes:

PraedSt
2008-Oct-21, 05:57 AM
What would be the cost of a large rotating colony, such as an O'Neill cylinder or Stanford torus?

Have you checked out the NSS site Siguy?
There's the original Stanford study that produced the torus:
http://www.nss.org/settlement/nasa/75SummerStudy/Table_of_Contents1.html

An online book about Space Colonies:
http://www.nss.org/settlement/ColoniesInSpace/index.html

Plus lost of other goodies!
You might be able to work out what the major cost determinants from these.
Anyway, if you have seen these before, sorry.

Larry Jacks
2008-Oct-21, 12:43 PM
What would be the cost of a large rotating colony, such as an O'Neill cylinder or Stanford torus?

Start with the design - work out all the detail (in detail, no hand-waving). Then, decide which construction technique (e.g. launched from Earth and assembled in orbit, mine lunar materials, etc.) you want to use. Only then can you begin to generate a rough order of magnitude estimate of the cost.

Noclevername
2008-Oct-28, 02:46 PM
There's just too many variables involved to hang a specific price tag on something like that. Methods of construction, type of habitat, processing methods and sources of materials, size, location, size of building crew, et multiple ceteras.

mugaliens
2008-Oct-28, 08:53 PM
Folks - long cylinders are unstable. Short cylinders and toroids are stable. Stability is achieved around the axis that exhibits the greatest radius of gyration.

The easiest construction would involve a tyvek-like donut in which progressively stronger layers of carbon fiber cord is glued in place on the outside before the inside is coated with a thin polyer (think saran wrap) before being pressurized. Once pressurized, spokes are attached, a hub is built, etc., ...

Van Rijn
2008-Oct-30, 12:42 AM
Folks - long cylinders are unstable.


I'm pretty sure this was mentioned before, but the O'Neill concept uses two counterrotating cylinders linked together. It takes care of the stability issue.