🚀 go-pugleaf

In article <1993Jan8.215514.22336@aio.jsc.nasa.gov> matthews@ial7.jsc.nasa.gov writes:

> There are many useful things to do with petroleum products other
> than produce energy -- they are useful as lubricants and are needed
> for the production of plastics and other petrochemicals.

They aren't *needed* for plastics, although they are currently the
cheapest feedstock.  We could make plastics out of any carbon source,
given energy and cleverness (we already know how to, just not
competitively).  I suspect our descendants will have sufficiently
better catalysts and cheap enough energy that petroleum would not be
of interest.

>>Powersats as usually described can't hack it as the primary energy
>>source for earth, since there's not enough room in GEO.  They'd have

> What does this mean?  Are you implying that powersats would be as restricted
> as comsats in "orbital slot" width?  Why?

I believe the problem was with shading during the equinoxes.  One
solution would be to make the individual powersats larger, with
multiple transmitters.  I don't know how big you can make them before
tides get too strong.


> There are reasons to think that a lunar surface-based solar power 
> infrastructure could be considerably cheaper than GEO powersats, due to
> the lack of a requirement to develop a very large-scale lunar surface-
> to-GEO transportation infrastructure for delivery of lunar raw materials
> for powersat manufacture.

I was wondering if someone would mention this.  This idea loses the
advantages of GEO powersats: ability to supply any site on earth
continuously, and the ability to keep the receiver in direct sunlight
at all times.  The first problem can be gotten around with orbital
reflectors, but that brings back the orbital debris problem (and makes
the transmission paths even longer).

Perhaps a better solution would be to use laser transmission from very
large orbits, perhaps using radiation pressure to keep the stations in
positions from which any debris is rapidly removed.  But laser
transmission has its own problems.

	Paul F. Dietz
	dietz@cs.rochester.edu