[ExI] Skylon as first stage.

[Keith Henson]

On Wed, Apr 20, 2011 at 10:44 PM, Kelly Anderson <kellycoinguy at gmail.com> wrote:
> On Wed, Apr 20, 2011 at 10:46 AM, Keith Henson <hkeithhenson at gmail.com> wrote:
>> But you really need big lift capacity from the earth before you go
>> after lunar materials.
>
> As I understand it, we have the material science to build a space
> elevator from the moon with current technology, where the space
> elevator from earth has to be built with a stronger belt than we can
> currently produce. That might serve as the basis for an argument to do
> things from the moon first.

It true we have the material, Spectra, and it happens that I am the
person who ran the calculation for a moving cable elevator off the
lunar surface.  The counterweight *alone* for a minimum sized (1000
t/day) lunar elevator came in at 65,000 tons.  Now if you have a 2500
ton per day materials lift for building power sats you can borrow the
parts shipments for 30 days and afford the rest, like 19,000 tons of
cable and a 15 MW power plant.

But to do this *first* before you have a solid production of power
satellites running and haul up the extraction and fabrications plants
to make lunar rock into useful parts, well, run the numbers, then
multiply them by whatever figure you think it will cost to lift the
stuff to GEO or beyond.

Keith