[ExI] Power satellites

[Dan]

--- On Wed, 4/22/09, Keith Henson <hkeithhenson at gmail.com> wrote:
> On Wed, Apr 22, 2009 at 6:20 AM, Dan
> <dan_ust at yahoo.com>
> wrote:
> >
> > --- On Tue, 4/21/09, Keith Henson <hkeithhenson at gmail.com>
> wrote:
> >> Even if moving cable space elevators are *never*
> built,
> >> they are still
> >> useful as the gold standard for space transport.
> >> $0.15 for the energy
> >> and a share of the capital to put one up.
> >
>> I would not use a hypothetical, untested technology as
> my "gold standard for space transport."
> 
> "Gold standard" in this context means, "Yah can't do
> betta:"  I.e., it
> is as the limit.

I think you could: nuclear pulse propulsion from the surface.  I haven't run the numbers, but there'd be no need for the huge capital investment of a space elevator AND most of the technology for it'd be off-the-shelf.  No need to develop nanotech further.  In fact, my guess is one could do nuclear pulse propulsion with decades old tech.  (Of course, there's the problem of pollution.)
 
>> All the numbers on their cost and efficiency are based
>> on speculation.
> 
> No, they are based on utterly sound physics.

Until you've built and tested one, you can't know the costs -- which are economic -- or the physical efficiencies of an actual space elevator.  Were this not the case, there would never be any need for quality assurance and quality control; everything would simply worked as conceived.  You can, of course, make guesses, but, looking at past large scale engineering projects -- especially, ones for space travel -- it seems to me these guesses are often way off the mark.  (One can make similar claims about nuclear pulse propulsion, though it has a longer history and actual tests were done years ago with much of the underlying technology.  Certainly, nuclear weapons have been extensively tested.:)

Regards,

Dan