SPS & Beamed Energy Propulsion

--- In ssi_list@... "Charles F. Radley"
>
> > Right now, and for the foreseeable future, chemical rockets are
> the
> > cheapest and most reliable way to put any payload in space.
> >
> > If we wanted to build SPS today then the best launch systems
would
> > deposable rockets.
> >
> Doing it that way is prohibitively expensive.
>
> SPS will only become viable if we use exterrestrial resources to
> build them, e.g. from the Moon and asteroids. Out there, chemical
> rockets are not the only option. And shipping chemical propellants
> up from Earth is prohibitive.
>
> Mass drivers have been demonstrated in laboratories, no
breakthoughs
> are required, it is simply a matter of scaling up the lab
prototypes.
>
> Best regards,
>
> Charles R.

You missed the point.

How do you put a mass driver on the moon with out using some sort of
launch technology.

regardless of how much lunar or asteroid resources you use you still
need to launch stuff from earth.

Keep in mind SPS could be built from earth material or from lunar
materials. Building the SPS for Lunar material is cheeper only if
you do not count the cost of building the moon base first.

by the way ... I am in favor of doing it the way you suggested.

Jeffrey