Space Habs

From: Dan Wylie-Sears

> Does spinning force us up to a certain scale in mass and volume, or only in length?

You're right in thinking it's primarily length of axis.

> The reason I see for a minimum scale is radiation shielding: a couple meters' thickness
> of stuff around the outside of a two-bedroom apartment is basically the whole mass of the
> thing, whereas around a billion-person habitat the same thickness is insignificant.

One of the reasons why Gerard O'Neill thought that larger-scale habitats might still be economical, right up to the point where structural mass becomes so great that it eliminates the need for additional shielding mass (Island 3 scale).

> and mass used for radiation shielding has to be supported if it spins with the habitat.

And you're right for putting an "if" in there, as there are designs where the shielding mass needn't rotate with the habitat. Of course those are for spheres and tori for the most part. The kind of baton structure we've been talking about would probably require integrated shielding. The only alternative I can see to that is perhaps a dumb-bell habitat rotating inside a toroidal radiation shield. And I can see only one reason for building such a habitat with such a high-mass shield: your intention all along was to allow for future expansion with additional dumb-bells, until one gets to the beaded torus geometry.

> So if drugs or vibration or whatever turn out to work ok, there will be incentive to
> use them instead of rotation.

Marshall Savage seemed optimistic about electro-stimulation. I'm not certain I share that optimism.

Regards,

Mike Combs