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Writing: Input Wanted Design of large rotating asteroid interior space

  1. May 31, 2017 #1
    Hi. I'm working on a science fiction story about colonization of the solar system. Asteroid way stations are an important part of the story. I want to construct a realistic scenario about how we could convert the Eros asteroid into a shuttling habitat in it's current orbit (or something close to it). The habitat should be a desirable residence for all socio-economic levels. I think this requires "very high ceilings", or wide-open spaces interior to the habitat. Something like Rama, but maybe with more topographic partitioning.

    On one end is a huge mirror (mylar-like substance, generated in place?). This will focus solar energy on an optical power system that will feed into an optical system that provides intense power to an industrial complex at one end of the cylindrical body. This will power multiple systems:
    1) An illumination system that will pipe light down a central longitudinal axis of the cylinder and mimic and earth day.
    2) A water purification and recycling system that will vaporize water flowing into the heated end of the asteroid, lifting it from the rotating edge to the sky-high center, where it will be fed down the central axial pipe to be distributed as controlled precipitation.
    3) In conjunction with the water flow, perhaps we could do some steam turbine driving as we condense the steam to water.

    A central question in this habitat is how do we manage the large internal volumes of air and water. I envision there being an atmosphere (perhaps higher O2 and lower N2 than Earth, with added He) at some tolerable level, perhaps much less than Earth sea-level.

    Will there be chaotic weather systems due to the dynamics of the rotating cylinder? One fallacy that I see a lot in these discussions is to equate a spinning cylinder's "artificial gravity" with Earth gravity. They are very different animals. Earth's gravity is a field effect that falls off with the square of the distance from Earth. Our Eros gravity is an artifact of the conservation of motion, that creates a force at a surface that is rotating around a central point. This force is valid for objects that are bound to the rotating surface. The whole system is relative to the inertial frame outside of the cylinder.

    One consequence of this difference is to consider the "gravity gradient" within the cylinder. Most discussions assume a linear "artificial gravity" gradient between the rotating edge (1G) and the axis (0G). This is theoretically true, but is only actualized if there is a surface at a given altitude/radius to transmit the force. Otherwise the effect on a fluid (air/water) at a given elevation (altitude/radius) will depend on interactions between the fluid particles (viscosity). This becomes a complex modeling situation. Input on modeling and control systems is appreciated.

    In order to manage this, we want to define a topology for the interior rotating surface and some type of air flow management system at higher altitudes, perhaps airships with deflecting surfaces or other air deflecting surfaces tied to the axis.

    Any and all input is appreciated.
  2. jcsd
  3. Jun 1, 2017 #2
    Coriolis forces will be definitally more significant than on Earth.

    Personally i prefer inner fusion reactor to power large space colonies.

    i thought about a zero-G ball game at the axis.
  4. Jun 1, 2017 #3
    Yes. Coriolis forces will be a major influence on the dynamics of the bodies of air and water inside of the large chambers. Intense cyclones are likely if there are not baffling surfaces to inhibit their formation. That's what I am trying to work out. For the lower altititudes, I am thinking of mountains. For higher altitudes, I am thinking of a network of airships that support and control baffle grids. These could also support management of precipitation. Lots of fun things are possible in the micro-g air near the axis. With only minimal propulsion (wings, compressed air jets) people will be able to fly around.

    Nuclear power would defintely be part of the picture, especially during initial construction and startup.

    The vast majority of people will reside "underground" in smaller chambers, structured as cities/towns. The upper large chambers are for Earth wildlife and recreation.
  5. Jun 1, 2017 #4
    Have you looked at Titan by John Varley?
  6. Jun 1, 2017 #5


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    how so with minimal propulsion?
    One has to remain above the curved surface or you crash.
  7. Jun 1, 2017 #6
    I have not. I will check it out.
  8. Jun 1, 2017 #7
  9. Jun 1, 2017 #8
    True, but at high altitudes, you might be 2 or 3 miles from the 1g (or maybe 0.8g) surface, and the centripetal force that you lose when you are no longer being supported by a rotating curved surface at that altitude would be very small (say 0.05g) and so could be managed with minimal propulsion. In fact, you could probably compensate for it by simply jumping up.

    I really want to get this right. The path of ballistic objects within the rotating cylinder depends on the relation between their initial velocity at that radius, the magnitude of the centripetal force at that radius, and the force vector of the impulse.
  10. Jun 15, 2017 #9
    You lights are unnecessarily complicated and low quality. Most of sunlight is not visible. You can use light emitting diodes to create visible light in habitat spaces. Use red and blue LEDs for plants. If you "pipe" solar heat in then you have to add pumps and pipelines to extract heat back out. If you have a lot of activity going on then your radiator starts to look like a huge panel hanging outside. Better to just use a solar panel floating outside where it will be its own radiator. Then run the electricity over to the habitat.

    You can model a rotating by stirring your coffee. The center has lower pressure not much mass is standing still. A few kilometers surface should not be too bad for weather. You can avoid that by including a ceiling.

    One of Kim Stanley-Robinson's books had a simulated ocean beach. They set up the wave break in a cork screw. You could surf a tube for a few kilometers and then swim a short lateral distance and catch another one.
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