Diversification

From: Ian Woollard [mailto:ian.woollard@...]

It seems to me that if we build stuff from lunar or asteroidal material
reentering it is probably very cheap.

I must allow that returning material to the Earth is probably going to be
much cheaper than lifting things up from the Earth, due to aerobraking. But
one must still place the payload on an atmosphere-intercepting trajectory.
That still takes a certain amount of delta-V, which is going to be
expensive. Aerobraking is a discount, but it's not a free ride.

This is one reason why I've always favored the SPS plan. There, our
"export" to Earth is in fact an orbital asset that remains in space, and
what Earth is "importing" is energy, which can be beamed down. I'm almost
afraid that any export to Earth which involved space transportation is going
to have a very hard time competing with other sources on Earth which don't
require space travel to get their products to their destinations.

In my more optimistic moments, I'm almost willing to allow that export of
platinum group metals to Earth may be just barely profitable. But I still
consider that an outside possibility.

The only thing this costs is mass,
and if mass is plentiful (asteroidal and lunar material is *fairly*
cheap,

Such material will always be much more expensive than any Earth-derived
material, since its retrieval will always involve space travel. That said,
it can be cheaper than the same amount of material boosted into space from
the Earth's surface.

and energy is plentiful from the Sun,)

That is one very strong advantage space manufacturing has going for it. But
on the other hand, raw materials will always be more expensive compared to
the situation here on Earth. That's going to result in our doing things
quite differently from the way we do them here (for example, complete
recycling of all waste products instead of just dumping it somewhere and
buying new raw materials). But I can't see space manufacturing having such
an advantage that it becomes preferable to Earth manufacturing for products
whose end use is on Earth. I still think we should concentrate on markets
for products whose end use is in space.

Regards,

Mike Combs

From:
Ian Woollard [mailto:ian.woollard@...]
It seems to me that if we build stuff from lunar or asteroidal material
reentering it is probably very cheap.

I must allow that returning material to the Earth is probably going to be much cheaper than lifting things up from the Earth, due to aerobraking. But one must still place the payload on an atmosphere-intercepting trajectory. That still takes a certain amount of delta-V, which is going to be expensive. Aerobraking is a discount, but it's not a free ride.

This is one reason why I've always favored the SPS plan. There, our "export" to Earth is in fact an orbital asset that remains in space, and what Earth is "importing" is energy, which can be beamed down. I'm almost afraid that any export to Earth which involved space transportation is going to have a very hard time competing with other sources on Earth which don't require space travel to get their products to their destinations.

In my more optimistic moments, I'm almost willing to allow that export of platinum group metals to Earth may be just barely profitable. But I still consider that an outside possibility.

The only thing this costs is mass,
and if mass is plentiful (asteroidal and lunar material is *fairly*
cheap,

Such material will always be much more expensive than any Earth-derived material, since its retrieval will always involve space travel. That said, it
can
be cheaper than the same amount of material boosted into space from the Earth's surface.

and energy is plentiful from the Sun,)

That is one very strong advantage space manufacturing has going for it. But on the other hand, raw materials will always be more expensive compared to the situation here on Earth. That's going to result in our doing things quite differently from the way we do them here (for example, complete recycling of all waste products instead of just dumping it somewhere and buying new raw materials). But I can't see space manufacturing having such an advantage that it becomes preferable to Earth manufacturing for products whose end use is on Earth. I still think we should concentrate on markets for products whose end use is in space.

Regards,
Mike Combs