Re: SPACE: Economic Benefit of Manned Space Stations (fwd)
Wed, 28 Jul 1999 22:32:20 -0700

Robert J. Bradbury, <>, writes:
> I've also got a C program that does a "brute force" simulation of
> a planetary disassembly using exponentially growing energy availability
> if anyone wants to tinker with it. If anyone is good with graphics
> adding "visual" output would make this a great toy. It takes apart
> the small planets quite quickly, while Jupiter takes many CPU hours.
> Of course, IMHO, simulating taking apart Jupiter *has* to be a better
> use of excess CPU cycles compared to certain *other* recently discussed
> uses of such resources...

Isaac Asimov wrote an article once about the advantages of taking the planets apart. He was thinking in terms of living room, not being exposed to modern ideas, but the same general principle applies for most uses of matter. You can do a lot more with it if you spread it out to where you can get at it.

He envisioned all the bodies in the solar system being torn apart, one by one, and put to use, except for one: Earth, preserved for sentimental reasons. Eventually the economic pressures become too great, and finally a fleet of disassemblers converges on Earth itself, the jewel of the solar system, to be converted to dust and useful matter. It was quite a moving description.

> Last year I asked Robert Freitas (one of the authors on the NASA
> study), what the advantages were for nanotech based self-replicating
> factories vs. the macro-scale versions envisioned in the NASA study?
> He gave a rather succinct answer that summed up the basic reason
> nanoscale manufacture trumps macroscale -- "The parts count is lower".
> You only need ~10-15 part-types (i.e. elements) for most nanoscale
> manufacturing.

I have trouble getting a clear understanding of what the "parts" are in nanotech. Most workers in the field will explain that they aren't literally planning on putting things together atom by atom. Rather, there will be molecular building blocks and complex work sequences which can assemble a wide variety of useful structures. So I think it is misleading to think of nanotech as having only a few "parts". I gather that there will be a large number of building block molecules and modification enzymes (which act as tools) which will have to be brought into play in the proper sequence in order to construct materials.

Where these building blocks and tools come from is not clear, but I gather that conventional, bulk chemistry would be involved. A nanotech assembler will have to be part of a relatively large and complicated system which produces the wide variety of feed stocks that it needs to perform its tasks.