space elevator (was CEV - Orion)

--- In spacesettlers@yahoogroups.com, "Chris Smyth" wrote:
>
> --- In spacesettlers@yahoogroups.com, "ANTIcarrot"
> wrote:
> >
> > > From: Chris Smyth
> > > Assuming a tether of approximately a mile in length (1600
> > > meters+)
> >
> > No, at one mile there is no limit to the weight that could be
> supported; though to hang ocean liners off the end you would need a
> rather thick cable.
> >
> > The long version (along with lots of fun mathematics) can be found
> here: http://en.wikipedia.org/wiki/Tensile_strength
> >
> Hi John,
>
> Thanks for the link - it has a lot of interesting and useful
> information for a layman like myself. As a follow-up to my post, I'm
> wondering: is a "tethered space hotel" a likely first generation
> configuration for a commercial presence in space?
>
> The reason I ask this is that astronauts returning from long stays
> on the ISS tend to suffer from loss of muscle and bone density which
> they mitigate by a rather rigorous regimen of exercise. I don't
> see "civilians" - particularly tourists - being receptive to these
> health effects (even if only temporary) or to the daily exercise
> required to counteract them.
>

I'm not exactly sure what you are describing here. Are you describing
a rotating barbell arrangement where the 'gravity' comes from
centriptal acceleration or are you describing a long tether where
gravity is based on the fact that one end is not moving at orbital
speed. (For the purest out there, I realize that this is the same
effect with vastly different radius.)

If it is the first case, all the dynamics of a space habitats apply.
If the later it would be necessary to develop a model for the dymanics
before being able to discuss this rationally.

> If a "tethered" configuration is used, would it require a central
> hub for docking? Also, would it require a sort of pressurized
> "elevator" to "lower" passengers and supplies along the cable to the
> habitats at each end? If so, assuming redundant cables to each
> habitat, would one pair of "elevators' running on one cable have
> to "ascend" to the hub while another set of "elevators"
> simutaneously "descended" on the other cable to each of the habitats
> in order for the whole complex to maintain rotational stability?

Any configuration would require a 'central hub' for docking. The space
ship needs to dock with the space structure with zero delta V.
Rotational velocity can most easiest be matched where the structure is
moving the least.

In the case of the elevator, the answer depends on the mass of the
elevator. If the elevator mass is a substanial fraction of the mass of
the entire structure, then moving it down will destablize the
structure. If the elevator mass is a small percentage of the the
total, it will produce a small wobble, which could be cancelled by
having active mass that can be moved a small amount to cancel the wobble.

>
> Finally, is this whole idea of a "tethered" space hotel too
> complicated? Would it be easier to just build an "I" shaped structure
> with a central hub as a first generation space hotel?
>
> Anyone have any thoughts on this?
>
I think the I shaped structure is the way to go.

Bill