HackingTheUniverse

Previous articles in this series:
1-INTRODUCTION
2-GEOGRAPHY AND GEOLOGY
3-GETTING THERE
4-MINING

HABITATS

• Choices – are limited by a need for rotational symmetry so that the habitat can turn steadily to create artificial gravity. All of these shapes are designed to provide living space on the inside surface with rotational force pushing everything “down” toward the outer rim.
  • Sphere –
    
    

    Sphere – habitat – interior

  • Cylinder –
    
    

    Cylinder – habitat – interior

  • Ring/Torus –
    
    

    Ring – habitat – interior

Megastructures E04: Rotating Habitats

– [youtube.com]

• Ring habitats offer construction efficiencies over spheres and cylinders because there is more effective usable space. Most popular illustrations show all three types being designed as mostly Earth-like terrain with open sky and mostly low or even single story building structures. Perhaps the reason for this is because of the principle that a space habitat needs to be completely self sufficient and that concept invokes imagery of farmlands and open spaces with blue sky above. The most efficient design is a multi-story ring with no terrain and no sky. In effect, this makes it a huge skyscraper with hundreds of stories that curve around in a large circle. While the habitat does indeed need to be self sufficient, this is not determined by abstract design elements, but by ability to produce atmosphere, water, food, energy, and to recycle waste products. The shape of a building has little to do with this. Engineering facts like tensile strength of the construction materials being used will play a more determinant role in the shape of the building.
• Dimensions will be mostly determined by the strength of the construction materials, but also by radius and rotational speed. Small radius rings need to turn faster to generate the same “downward” force toward the outer edge while larger radius rings can turn at slower speeds. Above 2.0 Revolutions Per Minute (RPM) there may be varying physiological effects from the rotational speed, but below that speed, there are none. It is also desirable to maintain at least 1/3 of Earth normal gravity to avoid any negative physical health impact without needing constant exercise. This gives us a simple “sweet spot” determined by ring radius and rotational speed of how many floors we can build up from the outside edge of a ring. We start by setting the RPM so that at the maximum radius (outer edge) the Psuedo Gravity (PG) is 1.0 Earth normal. Then we can build floors up from that until the PG reaches 1/3 and we want to stop building at that level. At least that is true for human occupancy quarters. Lower PG areas can still be used for agriculture and storage and other purposes.

  Here are some sample numbers: for a ring with a radius of 1,000 meters, an RPM speed of .95 will produce 1.01 PGs at the outer edge. At an inner radius of 400 meters with the same RPM, the downward force will be 0.4 PGs. If we use a floor height of 5 meters, we can build 120 floors above the outer edge with varying G forces found at each level, but within the range of 1 PG to .4 PGs.

  The width of each ring section will likely be determined by construction considerations. With an average width (it might make sense to taper the width from inner floors to outer floors) of 380 meters, we get just over 200 million square meters of floor space. Assigning 150 square meters to each person, we can house a population of 1.3 million people in this size ring.
  [Median radius 700 meters, median circumference 4.4 km, average width 380 meters, height 600 meters (1,000 on outer edge minus 400 on inner edge)]

• Construction
• Raw materials will be supplied from mining asteroids
• Energy will be supplied from photovoltaic solar collecters
• Automated manufacturing plants like giant 3D printers will extrude beams and walls and panels
• Robotic workers will assemble components into the ring habitat
• Life support
• Air and water will be extracted from asteroid mining
• Food will be produced from algae tanks and food processing machines will form it into a variety of attractive forms
• Electric power will come from a photovoltaic solar collector field outside of ring
• Environmental protection:
• Radiation shielding will be provided by an outer rim of 10 meters of regolith and stored water in layers of ceramic foam filters
• Temperature and humidity control will be maintained
• Light will be provided from electric power

The next article in this series will be about:
LIFESTYLE