RE: starship-design: HIGHLY OPTIMIZED TOLERANCE

["L. Parker" <lparker@cacaphony.net>]

John,

Not to speak one way or the other on the make it yourself thing, but your
suggestion:

> A better suggestion may be to design a "generic" logic module
> using modern
> technology. I'm not suggesting a few gates on a board as in
> the 80s I am
> suggesting a 32 Bit ARM processor, a DSP, 160k of program
> flash, 8Mbits of
> data flash, 12k of RAM, a USB port, an IRDA port, some A/D
> channels, some
> D/A channels, somer general purpose IO pins. This could be
> built on a 2x3
> board that uses very low current (50ma with both CPU and DSP
> cooking at
> 22/80 mips) at 3.0 volts using available (off the shelf)
> technology for $20
> a board in medium volumes at about 2 oz a board.

has quite a bit of merit. Programmable Gate Arrays are just now beginning to
come back into their own and can rival even the latest Pentium processors in
power. More so in that for a particular application, you can literally hard
wire the code into the processor resulting in blindingly fast execution.
Want to change the application? Just "reprogram" the gates, presto, a new
dedicated processor.

>
> In place of your 300 lbs of machine you could carry 2400
> spares for $48000.
> Considering a desk-top fab will probably cost Millions, which
> excludes the
> packaging and testing equipment also required.

I think you should probably add a few zeroes to this figure, but it still
makes more sense than a dedicated fab plant.

>
> The real difference is that you have to get used to the
> concept that in
> some things, such as modern electronics, you are often better
> off to throw
> a bunch of parts at a simple task than to make something custom.

Kelly already discovered this with consumables. It turns out that weight
wise it is easier and more economical to carry stores than to attempt to
implement a completely self sustaining closed eco system for any trip less
than about a hundred years. Most of us here are not trying to build a
generation ship anyway, so the same reasoning applies. Design the ship to
last for the length of the voyage plan on some repairs, use modular
components wherever possible, and cross your fingers...

>
> Another way to extend the mission duration is to send supply
> ships ahead,
> or send them faster from behind with some replacement stuff.
> Since "stuff"
> doesn't need gravity or environmental controls or oxygen or
> food or water
> it can be moved much faster and much cheaper than we can move people.
> Although re-supply may be distasteful to "pure" starship travel the
> reallity is that even here on earth it was, and is, considered normal.
> Aircraft carriers and submarines and space stations do it, the only
> difference is distance.

Practical idea in theory, and it may be the only way. However, logistically,
it will not be anywhere as easy as you make it sound. I tend to prefer the
first mission as a Pathfinder mission, specialized crew of around ten to
twenty, LOTS of computer support, running fast and light. It would be sent
to targets that had already been identified as special in some way, such as
the presence of Oxygen in the spectrum of its planets.

The Explorer mission would follow only after a Pathfinder reported back that
there was a reason for more extensive exploration, such as a potentially
habitable planet, or perhaps just to study life already there. This mission
would actually be a small fleet consisting of the Explorer ship itself, and
several freighters slaved to the Explorer. The freighters would carry
spares, extra supplies, machinery, tools, and intrasystem craft including
landers. The Explorer mission would consist of several hundred to several
thousand people, enough to establish at least a permanent research presence,
including establishing mining and manufacturing operations sufficient to
support the mission and any follow on missions.

The last mission would be the Caravan mission. This is the big one. The
colonists would arrive in one or more very large ships, hopefully in some
sort of cryo sleep to conserve mass, so that the trip would go faster with
fewer support craft or resupplies. Tools, supplies and machinery needed by
the colonists would already be there ahead of them, built by the automated
factories put in place by the Explorer crew.

I agree that FTL probably won't happen any time soon, and that isn't the
purpose of this list anyway. I DO think we will be able to reach close to
the speed of light with derivatives of today's technology within a hundred
years. It is after all really nothing more than a brute force application of
things we already know or suspect how to do.

Lee