[ExI] Power satellites

[Eric Messick]

spike writes:

>There is no absolute physical limit, but there are practical limits.  As
>Eugen put it, the rocket equation is a cruel thing.  Yes this is a big
>planet for chemical rockets.

Well, actually there is an absolute physical limit.  Get the mass of
the 'planet' up high enough, and you get an event horizon.  I'll
admit, the limit is pretty far from where we are, but it is there.

A question to Keith about 'pop up and push':

With a fixed array of lasers on the ground, might it make sense to do
the last bit of the pop up part by laser?  The geometry may be such
that you couldn't reuse the push lasers for this, which would limit
the usefulness.  If you're cranking out a production line of those
lasers anyway, it could make sense to throw a set near the launch
site, though.  Maybe you eventually end up with a completely laser
powered launch.