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This discussion might be interesting to SSI folks.

Regards,
Mike Combs

> The space community is wary of mega-structures that would be required for rotating space habs.

> Alglobus suggests that we could reduce the size of these structures by constructing them within

> the natural radiation shield of planet Earth - which would reduce the size of these mega-structures

> substantially.

Youre making some excellent points, and this is an interesting discussion. But I would caution against referring to ONeill-scale habitats as mega-structures
for the following reason. There is a large sci-fi-reading community for whom the term mega-structures means things like ring-worlds, Dyson spheres, Bishop rings, etc. All of which are well outside of
the strength-to-weight limits of currently available building materials. I think an important point we must constantly stress when discussing ONeills concepts is that they are all well within the limits of currently-available construction materials.

Im not sure what alternate term I would suggest. Miles-across structures? High Frontier structures? Some people just say ONeills.

> 1. The hull - Tourists can entertain themselves inside the hull in vacuum, wearing pressure suits.

> Tourists could base themselves in nearby Bigelow constructed space habs.

Interesting. And the radiation shield would be one of the easier things to construct (and it would benefit the construction crew if it was completed at an early point). So such tourists would benefit from the shielding.
Temperature management would become easier too, I would think.

One interesting aspect of this proposal is that you could let tourists space-walk to their hearts content without worrying about them drifting off to another orbit. On the other hand, I think one of the prime draws of space-walks will be the view of the universe.

> 2. The hull pressurized with air - Tourists can spend time in a large zero g enclosure without

> pressure suits.
> 3. The hull pressurized and spun.

2 sounds like lots of fun.

3 raises the interesting point that a space habitat might be able to start generating revenue even before the interior landscaping is significantly far along. Almost anyone on Earth would want to vacation in a habitat with interior landscaping like the Hawaiian
islands. But some people would be happy to visit a bare metal hull, just to say that they visited a space habitat.

But 2 and 3 taken together raises an interesting issue. In what order should certain steps proceed in the construction of a space habitat? In the college seminar I got to be in, I raised that question. ONeill said, Theres lots of smart people in this
room. With a bit of discussion, we could work it out. But then we went off to another topic and never came back to this.

(I dont know if that was ONeill being gracious, or him side-stepping an aspect of this which never got deeply thought-out.)

A part of me thinks: build the structure first, spin it up second, and then pressurize (from the outer rim) third. My reasoning is that if you pressurize second, and then spin up third, the atmosphere wont be all that tightly-coupled with the hull. You might
initially find yourself facing hurricane-force winds, at least a few feet above the hull.

But maybe hurricane-force is overstating it a little. And maybe the advantages of having a pressurized hull (we can start working in shirt-sleeve) even prior to having much gravity might outweigh the problems of stiff winds for a temporary period.

What say the rest of you?

> Are there ideas on how the hull can be constructed - at minimum cost?
> Would some kind of winding process work out cheaper?

I think the least-expensive-sounding idea Ive heard is vacuum vapor deposition of metal on a rotating balloon form. But that was visualized for ONeill-type structures (a few miles across). Might not scale to
the smaller structures we presently envision starting out with (with the assumption of modular components brought up from Earth). Im unsure about this.

Regards,
Mike Combs

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