Space colony

A space colony is a megastructure in space where people live. Space colonies come in several arrangements. What follows includes many of the most common types.

• O'Neill Cylinders -- Also known as "Island-3" colonies, these are far and away the most common type. These come in two flavors: "Open-type" colonies, which only make use of half of the interior surface for habitation space and cover the remainder in transparent "sky" panels, and "closed-type" colonies, which remove the "sky" panels and are inhabited the whole way through.
• Stanford Torus -- A Stanford torus is a colony similar in shape to a donut, housing less than 150,000 residents. A Stanford torus was to be the home of the Federation's chief executive, but the destruction of this colony in a terror attack turned people off to the design.
• PLANT - Similar in shape to an hourglass, a PLANT is essentially two O'Neill cylinders joined at the thin end.
• Bernal Sphere - Also known as "Island-1" or "Island-2" colonies, Bernal spheres consist of a central habitation sphere and other components.
• Asteroid Base - Many asteroids have been turned into semi-functioning space colonies by building facilities along the interior after ore extraction.
• Island-4 - Island-4s are a flat, disc-like colony model using Zentradi technology to provide artificial gravity, and are most common as attachments to exploration fleets like the Frontier Fleet. Neo Colonies use a pseudo-Island 4 design.