Lagrange Point Habitat
I am thinking we would want a sphere about one mile in diameter. Spin it at a rate of one revolution per minute and you would have one gravity of acceleration at the largest radius. I like the idea of making the surface of the sphere out of foot thick steel, but this may not be the right choice. The skin of the sphere will have several functions:
- Keep air and water vapor inside
- Keep dangerous radiation outside
- Absorb and/or deflect meteors and other debris
- Hold itself together, i.e. have some structural integrity
A large diameter cylinder would be fitted to the inside of the sphere and concentric with axis of spin. It would take up one third to one half of its' length. This would give us a large surface of even gravity on which which to house our people. A cylinder a third of a mile long and one mile in diameter would give us about one square mile of "land": 640 acres. We should be able to do something with this, perhaps farm, or even raise cows. The area between the cylinder and the skin of the sphere could be used for water tanks. In case of a breech of the hull, large valves could be opened into these tanks and quickly drain any surface water into the tanks before it all evaporated into space. Water in these tanks could also be transferred around the diameter of the sphere to compensate for any imbalance.
The large diameter offers several advantages:
- Low gravity gradient. There would little difference in the apparent force of "gravity" as you changed elevation. For instance there would a negligible difference between your head and your feet, and the difference would still be small for an elevation change of 100 feet.
- Slow spin rate. I would hope that an angular velocity of one revolution per minute would minimize any problems with vertigo either for permanent residents or visitors. As far as I know there is no way to tell. Research and testing will be necessary.
- High linear velocity. The high linear speed of 200 MPH means that any motion in the vessel, like walking, will have a minimal effect on your perceived weight. Running, either with or against the rotation, will no doubt have a noticeable effect, though it should be something most people should be able to deal with.
- Wide open spaces. Having a "ceiling" a thousand feet in the air would give people a feeling of wide open spaces like they have on the Earth's surface. It might help prevent attacks of agoraphobia in people returning to Earth, and attacks of claustrophobia in people arriving at the habitat.
- Large volume of air. This means that we can survive small leaks until they are found and a small amount of anything unpleasant or noxious would be diluted to the point where it is harmless.
- contact with a long probe which would stabilise the vessel's position and relative velocity.
- with the aid of the probe the vessel would be maneuvered into position directly outside the sphere and in-line with its' axis of rotation
- a cage-like frame would close about the vessel and be secured
- the cage would be drawn into the sphere
- the cage, and the contained vessel, would be spun up to match the sphere's rotation
- the cage would be moved sideways, relative to the axis to a docking berth
In most cases docking could be carried out in vacuum, but there will be cases where bringing the vessel into a pressurized chamber would make things easier. Emergency would be one case, and external repairs would be another. It is easier to build and seal a small door rather than a large door. If vessels where constructed as long cylinders, then they could enter a pressurized chamber through a relatively small door. So pressurized docking chambers would be cylinders perhaps three times the diameter of a vessel and slightly longer.
We would probably not need to accommodate winged vessels like the space shuttle. We would be a long ways from anyplace where wings would be useful. The expense of boosting them this far out would be very hard to justify. However, if this structure is going to be a mile in diameter, just how big are the ships going to be? Right now I find it difficult to imagine anything larger than about 30 feet, but I have seen numerous engineering projects that had to be revised to accommodate the bigger, larger and more powerful.
At one point I was thinking that sand would be the perfect material to use for shielding the outer skin of the sphere. Easy to transfer, simply pour from one container to another. Good for absorbing impacts from micrometeorites and cosmic rays. And it could be used as a raw material. Apply enough heat and you get oxygen and silicon. Oxygen is always handy for air breathing mammals. Problem is any small holes in the "underside" of the containing vessel would let the sand drain out and be lost. There are ways to compensate, like putting a chamber below the sand to catch any that leaks out, and allow maintenance to plug whatever holes show up in the floor of the sand chamber.
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