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Re: starship-design: New discussion

In a message dated 7/18/97 8:29:10 PM, jimaclem@juno.com wrote:

>	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

Excelent topic change!!  Also important for my fuel/sail configuration.

Yes, if you assume the microwave generators are a fleet of large solar power
sats (like those proposed in O'Neils space colonization concepts), each phase
linked together during transmition, with each platform about 10 x 100
kilometers.  So with about a thousand sqaure kilometers per platform.  2 *
10^6 kilowatts of power per square kilometer of collector at Mercuryvill
distance from the sun.  Thats 2 * 10^9 kilowatts of power per platform (about
1,000 times the power output of a standard comercial power plant).  So you
need a 5 million platform power array to produce the the10^15 kilowatts
needed to boost these ships out of Sol space.

If these things cost about as much per kilowatt as curren big power plants
(about a billion dollars per 10,000 kilowatts I think).  The total bill would
be in the $ 10^18 range.  Obviously we need a way to drasticly reduce the
cost of power production to get these guys up to speed, or look for a more
cost effective launcher system.