COMMENT ⊗   VALID 00002 PAGES
C REC  PAGE   DESCRIPTION
C00001 00001
C00002 00002	NOTES ON SPACE COLONIES
C00005 ENDMK
C⊗;
NOTES ON SPACE COLONIES


	Dyson () has advanced several reasons for colonizing space: to disperse
mankind so that nuclear war can't destroy it, to provide a frontier so that
dissident groups can do things their own way.  Another reason is that living
in space might be fun.  It doesn't prevent Malthusian difficulties and since
it would be very expensive, it won't even help immediate problems, since a
person can be provided a capital base for good living on earth much more
cheaply than in space.

	I want to discuss the problem of space colonization from a different
standpoint than that of O'Neill (1972).  O'Neill proposes to simulate earth
environment rather well and to provide lots of living space.  In Appendix A
of this paper, I will show that O'Neill's proposals are impossibly expensive
in their present form.  Rather than start where he does and discuss ways of
reducing the cost, I will start at the other end of the scale.  Namely, I
want to explore the minimum cost alternatives on the assumption that there 
will be colonists willing to change their way of life drastically when they
emigrate.  Perhaps our colonists will need stronger motivations than his.

	As with O'Neill and Dyson before him, I shall assume that materials
obtained from the asteroid belt in the steady state are used to construct
vessels that use solar power and have closed ecologies.

	Unlike O'Neill, I shall assume that people will adapt to zero g (perhaps
they will prefer it even if they won't be able to visit earth without
re-adaptation) and I will assume an atmosphere of 5 lbs per square inch
of pure oxygen.

	Under these conditions, it turns out that the amount of material in
required for the pressure vessel is independent of the size of the vessel
and depends only moderately on the shape.  We shall start with a spherical
shape which is the most economical.