From: Technotranscendence (neptune@mars.superlink.net)
Date: Fri Apr 21 2000 - 08:14:34 MDT
On Thursday, April 20, 2000 4:59 AM Greg Burch GBurch1@aol.com wrote:
> > Is this really still true? How many parts were actually in a Saturn 5?
> > I would have to think that much of a Saturn 5 is nothing but big hunks
> > of sheet metal, fuel tanks and some plumbing. Size does not equal
> > complexity. The parts count on things like the 767 is in the millions
> > (though most of the parts are rivets). Then you have dozens of chips
> > out now in the 10-100 million transistor size range.
> >
> > I would bet that the complexity of the command module was greater than
> > that of the Saturn 5 itself.
>
> Having walked around the prone carcass of the vehicle that was to have
been
> Apollo 19 at JSC many times and having a passing layman's familiarity with
> the general design of the Apollo spacecraft, I'd say you're right on the
last
> score, certainly so if you include the Service Module in comparison to the
> Saturn rocket itself.
So? I'm only looking for a reliable, cheap heavy launch lifter -- not the
most complex thing ever built. Chances are, such a thing could be very
simple compared to other machines humans have built.
> On the other hand, the complexity of the ENGINES was
> pretty damned high -- amazing machines, they were, with lots of analog
logic
> built into the hydraulic systems.
That may be so. I'm not sure. What would be the problems with using analog
over digital in this area? (Off hand, I can think of positive feedback
being a big problem, but I imagine these engines were thoroughly tested and
highly rated. However, building them today is another matter.)
> > The minimum self-replicating bacteria, would seem to be able to
> > do basic metabolism *and* self replication with a unique parts
> > count of ~300.
> >
> > What should one use for *real* measures of complexity?
> >
> > For example, was the Apollo command module more or less complex
> > than an Iridium Satellite?
>
> Good question -- I'd say likely more complex even with physical systems
> considered alone, if only because of the broad range of function designed
> into the spacecraft, as well as the huge redundancy. If you consider the
> information systems, as well (embodied in the crew's training and the
ground
> support), the complexity of the CM far, far outstrips a modern comm sat.
Complexity is mostly relative, I believe, though I imagine a raw absolute
measure of complexity would be the number of parts a system has and their
interrelations. Still, how does one tell whether a system with x parts and
y relations is more complex than one with x+1 parts and y - 1 relations or
x-1 parts and y+1 relations? (This is assuming that all these things can be
discretely measured.) Of course, it's easy in a lot of paradigm cases. The
Space Shuttle appears much more complex than, say, a toilet bowl -- and I
think with good reason. But when we venture far from those instances, what
should guide us?
John L. Casti, in _Mind Rules_, argues that complexity is best looked at as
relative to the system with which the complex system interacts. (See vol.
1, pp21-3.)
I imagine, too, that in regard to this discussion we should not be worried
so much about complexity as just a pure theoretical construct, but in
regards to how easy it is to design, build, use, repair, and maintain a
space vehicle.
Cheers!
Daniel Ust
http://mars.superlink.net/neptune/
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