Bubbleworld is a stellar megastructure proposed as a space habitat by Dandridge M. Cole and Donald W. Cox. It was invented to answer the question "what is the largest space colony that can be built". However, most of the volume is not habitable and there is no power source. It's mainly a big empty hollow earth - it's primary benefits being size and ease of construction.
The bubbleworld is built from a large asteroid of iron or nickel (which describes plenty of them). You drill a tunnel through the longest axis of rotation, and fill it with water. Then you set up a huge solar reflector nearby. Using the reflector, you weld closed the openings you'd drilled. Then you begin heating and spinning the asteroid. The metal softens, the water expands, and in a short time you've got a big hollow cylinder. Heat the middle section a little more and it will bulge out. Allow it to cool and the metal will set. Keep it spinning, and as the water will turn liquid again it will collect in the bulge as a ring-shaped lake in the middle of the structure. Now it's just a matter of building access points and windows.
The solar reflector can probably be rewired or otherwise diverted to generate heat and energy for your new colony.
Game and Story Use
- Adventure Seed: Tentacles of Space
- With the right tech, this is a fast and cheap way to make really large space colonies. You only have to import the water and any internal furnishings or tech (like life support machinery) - the basic building materials of the framework are already sitting out there unclaimed in space.
- The big reflector has some good gaming possibilities. It could be that there's a company that goes about building large numbers of these habitats, in which case they'll probably have a single big reflector they haul around to do the job. Or it could be more "Do It Yourself", that you buy a reflector and later use it (or parts of it) to heat and power the bubbleworld. In either case, a huge space mirror that can turn sunlight into lasers, a welding torch, or a generator is pretty useful. If colonists are the self-made Determined Homesteader type, it's easy to picture them using such solar reflectors to defend their property.
- And indeed squatters and homesteaders in space seems like a fairly amusing campaign concept.