Re: O'Neill habitat spin axis

From: Ray Drouillard (cosmicpam2_at_comcast.net)
Date: 08/24/04 

To: sci-space-tech@moderators.isc.org
Date: Tue, 24 Aug 2004 19:44:21 -0400

How close is it going to be to the star? What is the orbital period?

If you make the habitat long enough, it'll just naturally want to keep
itself oriented with the long axis straight through the center of mass
of the primary. I believe NASA uses a long boom and counterweight to
keep satellites oriented towards the Earth.

That will still give you some interesting effects do to gyroscopic
inertia. That can be handled by hooking two counter-rotating together.
In fact, that has been proposed for O'Neill colonies. The pictures I
saw had the colonies set side-by-side, but it might be possible to put
one behind the other. You would have problems with the front colony's
mirrors shading the rear colony, though.

If simply making a really long colony won't do the job, using the same
long boom and weight trick that NASA uses ought to work. Or, instead of
a weight (or factory), you could put a colony pair on the other end of
the long boom.

If you do this, the boom will be under tension, and there will be some
tidal force at each end. It won't be much, but it might be worth
mentioning.

If I was designing an O'Neill colony for my WIP, I would do a google
search on "L5 society". I'm sure they have a web site, and I'm equally
sure that they have done lots of design work on various colonies. Also,
you might want to google on "O'Neill Colony".

Ray Drouillard

"Russell Wallace" <wallacethinmintr@eircom.net> wrote in message
news:412a03c1.116606037@news.eircom.net...
> I'm designing an O'Neill habitat for use in a game scenario, where I'm
> trying to keep the science as plausible as possible. It's going to be
> the classic "spinning tin can" design, surrounded by an array of solar
> panels, mirrors and radiators (and directly in orbit around a star,
> rather than a planet, though I could change that if there was reason
> to do so). My question is about the spin axis.
>
> I'd ideally like to point it at the sun. Then the nearside cap could
> be coated in solar cells while the rest of the surface is painted
> black to help radiate heat.
>
> But in that case, it seems that a quarter orbit later it'll be side on
> to the sun, another quarter orbit the opposite end will point at the
> sun etc, since conservation of angular momentum will tend to keep the
> spin axis pointing in the same direction relative to the rest of the
> universe, not relative to the sun.
>
> Is there any way to change that (I mean, reasonable ways, i.e. without
> expending propellant or using huge gyroscopes etc)? For example,
> Earth's axis precesses every 26,000 years IIRC; how does that square
> with conservation of angular momentum? Is there a way a habitat's axis
> could be made to "precess" through a full circle every year?
>
> Or if not, is the best solution then to orient it vertically, let most
> of the surface be mirror colored, and paint the end caps black?
>
> (Another question: Has anyone investigated the question of what the
> rate of leakage of volatiles from a habitat would be, and what would
> be the limiting factors on how low you could make it?)
>
> Thanks,
>
> --
> "Sore wa himitsu desu."
> To reply by email, remove
> the small snack from address.

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