For everybody's enjoyment - I've posted a response to Steve Fetter's
article on the FPS discussion board, and sent it to them
for consideration for their next issue. Fetter's response is in
the January print version of Physics and Society:

http://www.aps.org/units/fps/newsletters/2004/jan/index.html

and you can download my response here:

http://www.fpsboard.org/forums/download.php?Number=86

My summary is as follows, from
http://www.fpsboard.org/forums/showflat.php?Cat=&Board=pands&Number=86&Main=81
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The main point is that Fetter's 5 conditions, when corrected for actual
power market conditions, translate to 4 technology research challenges
for space power:

(1) The ratio of space to terrestrial solar module
costs needs to be at most a value of 3 (space three times more
expensive) - otherwise terrestrial power is always going to win out.

(2) The efficiency for wireless power transmission - a NASA goal was
40%, but higher efficiencies have been seen over short distances - can
they be achieved over tens of thousands of km?

(3) Mass per peak kW is too high: 1 kg/kW has been argued by others
to be achievable. Is it?

(4) Launch costs. $1000/kg, combined with the other technology targets,
may allow space power to be cost competitive. Can we get to orbit for
that, or less?

The energy transition problem is one that will cost 5-10 trillion
dollars or more over the next 50 years; a few billions spent on
investigating all the physically plausible alternatives seems like
money well spent.

Arthur Smith