"Hop David" wrote in message
...

We don't know what gravity's needed to stay healthy. This argument also
works against orbital habs. So long as mammoth O'Neill cylinders are
perceived as entry level orbital habs, people will dismiss them as
implausible science fiction.

But they most certainly should NOT view the O'Neill Cylinder as the entry
level orbital hab (though Zubrin, in trying to bias the argument, may
frequently pretend to think this is the case). An O'Neill Cylinder might
mass 1 billion tons. A Stanford Torus would mass 10 million tons, a Bernal
Sphere would come in at under 4 million tons, and a simple Space
Manufacturing Facility (even one with a rotating, radiation-shielded section
for housing) would mass much less still.

--


Regards,
Mike Combs
----------------------------------------------------------------------
By all that you hold dear on this good Earth
I bid you stand, Men of the West!
Aragorn