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RE: starship-design: New discussion

-----Original Message-----
From:	jimaclem@juno.com [SMTP:jimaclem@juno.com]
Sent:	Friday, July 18, 1997 1:49 PM
To:	starship-design@lists.uoregon.edu
Subject:	starship-design: New discussion


	Since my wild-haired ideas have been thoroughly picked at, I'll
go to another subject, power for the Argosey, M.A.R.S. concepts.  It is
stated in those documents that power on the order of 10^18 watts, or
10^15 kilowatts will be required to drive a heavy sail-craft.  Here's an
idea for getting that energy.  If you note the document on carbonaceous
chondrite asteroids, you will find that those appear to have a silicate
content of some 83 %.  If we mine these and use this material to build
solar panels, LARGE panels, and place them orbiting the sun at about the
orbit of Venus, we can get approximately 1 kilowatt for 3 m^2 of panel,
assuming a final conversion rate of 10%.  Thus one square kilometer of
panel will generate approximately 3 * 10^5 kilowatts.  Placing these at
the distance of Mercury will generate some 9 * 10^5 kilowatts.  Lets
assume that efficiency improvements will allow this to approximately
double, giving some 2 * 10^6 kilowatts.  10^15 kilowatts now can be
produced with some 1,000,000,000 square kilometers of panels, orbiting at
the same distance as Mercury.  (Yep, those numbers seem to be right). 
This gives a disk some 36,000 kilometers in diameter!!!!!  Just trying to
start a dialog on this problem, as this seems the best and quickest way
to get probes out there.

Jim Clem


That is a pretty good idea. However as an engineer, I'm sure that you are familiar with conversion efficiency. Sometime ago I mentioned an old article I read on a solar powered laser that was based on principles of geometry - in other words it was mechanical, a trick of mirrors. I believe it was in Scientific American, but I'm not sure. (If anyone out there is near a library with archives, please look. I'm in a backwater here, the nearest decent library is almost a hundred miles.) Anyway, it would be very simple to set up mass production of such a device to kick out millions of these things automatically. The hardest part would be the control circuitry to keep them aimed at the same approximate point in space.

Since it would be so low tech, we could send an advance probe to build an array at the other end to improve the flight times of subsequent colonization ships. Envision a small Starwisp type of probe with a ten pound payload of nanobots whose sole purpose would be to convert an asteroid belt into solar pumped lasers and control machinery. It might take it fifty years to get there and another fifty years to build the infrastructure, but after it was built we could put a M.A.R.S. or sail type ship up to near light speed quickly and then decelerate it at the other end without resorting to complicated magnetic loop braking, etc.

L. Parker