[ExI] Last week's travels

[Keith Henson]

Last week was brutal.  Mon. and Tue. in Chattanooga, TN for the
Tennessee Valley Interstellar Workshop.  Most of my time went into the
workshop sections on Power Satellites run by Robert Kennedy and Peter
Garretson.

Wed. morning I visited the people at the Arnold Engineering
Development Complex who built and operate a 50 MW arcjet.  They
confirmed the figures I have been using about efficiency, mass.and
life expectancy.  This 1967 paper applies
http://alfven.princeton.edu/papers/magnetarc.pdf

Late in the day I got on a plane to London which got me there around
Thursday noon.  Stayed the night at the Railway Inn, next to the
Culham train stop.  Spent two hours the next morning talking to the
whole engineering staff of Reaction Engines.  Me to them was mostly a
pep talk on using Skylon for building power satellites, ending the CO2
build up and getting off fossil fuels with cheap energy from space.
Them to me was a lengthy discussion about how fast production rates
could put pushed up to around 1700 vehicles a year.  The conclusion is
it can be done.  They already have the vacuum brazing furnace which
could make precoolers for some tens of Skylons per month.

Sat flew back.  Had an awful time from SFO to San Diego.  Rain was
coming down in buckets at San Francisco.  The weather was so foggy in
San Diego that we aborted the first landing attempt.  Planes don't
carry enough fuel to try again *and* divert, so we had to fly up to LA
for more fuel.  Landed on the second try.

Fortunately the age reversing treatments I have been on worked.  I
would not have been able to do this a few years ago before Regenexx
rebuilt my back.

Have made serious progress in the last few days refining the LEO to
GEO cost model with the propulsion power plants in space.  Normally
the cost to GEO using chemical fuels is about 2.5 times the cost in
LEO.  This adds about $180/kg to the $120 in LEO.  That's too much for
power satellites to undercut coal.  The previous model using
microwaves from the ground to power arcjets cost about $75/kg, making
the total less than the maximum of $200/kg but not much.  Using space
based power plants to power the transport gets the LEO to GEO
incremental cost down to somewhat less than $30/kg.  It also cut ~$15
B of the startup cost.

I don't post about power satellites on this list very often.  If you
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