concreting in space

>The way to look at it is this: the only thing which makes lunar material
>"ores" (which is only defined as material from which it is economical to
>extract a substance) is the high cost of lifting materials off the Earth.
>If not discussing in the context of major construction programs in cislunar
>space, we would call these ores "dirt", which is in fact what it is.
>

Mike,

I do not think of lunar material. I am thinking of material derived
from asteroids as near to sun as possible.

Were low gravitation makes it possible for solar sails to land on and
starting of with the additional help of ion thrusters
(for the solar sails I am thinking of see at
www.solar-thruster-sailor.info look under "STS")

The robotic construction process being in place near the asteroid.
So the asteroidal dirt would be ore in this case.

>It's like TangoMan said, who's your competition? Launch costs make dirt off
>the Earth economically competitive with the most highly prized ores found on
>the Earth.

But launch costs from the moon would be also more than launch costs
from an asteroid since the asteroid has only micro gravitation.

Frank