> Here's a question for our aerospace professionals (and space groupies like
> me): How quickly after the development of a general purpose programmable
> assembler could a completely "de novo space program" be developed, and how
> many (or rather, how few) people with what expertise would be necessary to do
> Here's the scenario that generates the question: Imagine that a "classic"
> Drexlerian assembler is developed . . .
For some reason I feel inspired, not to completely co-operate with your scenario, but to try to shoot it "down in flames" to some extent :^). Hmmm, the "classic assembler" would presumably be actually a nanofactory of some kind, something not too different from the "exemplar" nanofactory described in Chapter 14 of Drexler's _Nanosystems_. There, we have a quite capable diamondoid-based factory that is to be both self replicating and programmable for extrusion of many kinds of useful diamondoid-based products, also able to scale its own copies up to some quite large size. So, within the limits of the little molecular block assemblies that the nanofactory is meant to handle efficiently, it does become a very neat scenario to try to imagine what sort of space "program" could engineers readily "program"!
One thing that complicates this "classic" scenario is that before we get such a refined, reliable, and scalable factory, it is almost a given that some relatively more limited kinds of replicating nanotech will have to have been developed beforehand. For instance, computers based on proteins, or on other polymers, or computers based on carbon buckytubes, might well be common at the time we are imagining -- with this computer tech (and all the chemistry that goes along with it) being the key to breaking into the generally "tough and reliable" diamondoid stuff. Now, if we've got all these great new materials to put into computers and even into the mechanical structure of rockets and other things, then maybe at that point we'll be getting into quite an large scale, human oriented presence in space, *before* we have the "classic" or fully capable nanoassembler factory. In short, we first have some very effective bulk scale construction methods using materials that either self assemble or replicate in a quite limited fashion. Using this, we *may* have a number of interesting space initiatives already going or in the works *before* we get to truly "hackable" "Drex-boxes".
The above "nano guesswork" may perhaps seem a little more concrete if I suggest the possibility of an early, buckytube based, computer chip factory. Such an early nanofactory might only work if you can build up the basic components of it on a carefully prepared flat surface, or on "shelves" made of Teflon, or something like that. Now, in this imagined phase of development, you can actually "grow" your nanofactory setup, but only if you add more shelves, the shelves in turn may *not* be directly manufacturable by your early nanofactory! Meanwhile the nanofactory as such may be able to churn out some very dense memory chips, and maybe it could even be scaled up to produce significant amounts of high strength buckyfibre for construction use. In effect, can we readily imagine a very useful kind of self replicating "early nano" that would still be tied to bulk tech for making finished products? What I am really trying to get at here is that it isn't even clear whether one would need or want to take such an "early nano" technique to the Moon. While you are building neat computers and such down here on Earth, maybe all that you want to take to the Moon with you is some sort of bulk scale hydrolysis plant for making fuel out of the water that we know is there!
> I envision the following basic scheme:
> <> Some kind of very rapid recapitulation of the history of the manned and
> unmanned space programs. Thus a basic rocket booster would have to be
> developed and proven with a minimum of tests and versions. This booster
> would ideally be 1) modular (so that it can be employed for a range of
> payload weights) and 2) fueled by material that could be readily synthesized
> using assembler technology (hydrogen and oxygen from water?)
> <> A range of engines and fuel tankage systems . . .
This idea of getting a lunar outpost together quickly is an interesting one, however, it isn't clear to me that prototyping all new hardware, following a programmable factory breakthrough, is necessarily the way to go? Hackable factories are a very cool idea, however, besides the above mentioned complications, there is *another* point that bugs me about this! As I understand things, the best, most capable, soon-to-be-invented nanotech is most likely to be made of *carbon* in one form or another, right? Unfortunately, our own Moon seems to have no carbon content worth mining, so it's sort of a bust for an on the spot diamondoid factory anyway. Good location, but it doesn't have the right material for the best of early nanotech! So maybe your early lunar getaway shouldn't be nanotech so much, or maybe you should go straight to Mars and its moons, for the carbon?
David Blenkinsop <email@example.com>