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Space colony

Artificial habitats in space that housed most of humanity.
Jenxi Seow Published 20 Jul 2018 Updated 13 Feb 2025
Space colony

A space colony was a massive artificial habitat constructed to house humanity in space. By the Universal Century era, the majority of human population lived in these colonies, which were primarily located at the Lagrange points between Earth and the Moon.

History

The Earth Federation began constructing space colonies in the late 21st century as part of its Space Settlement Plan to address Earth’s overpopulation and environmental problems. The first colonies were small experimental habitats, but by UC 0001, multiple large-scale colony clusters called Sides were established at the Earth-Moon Lagrange points.

Each Side typically contained multiple colonies housing millions of inhabitants. The colonies operated under Earth Federation governance, though some like Side 3 and Side 6 later declared independence.

Design

Most colonies followed the O’Neill ‘Island 3’ design, consisting of two counter-rotating cylinders linked by a central shaft. Each cylinder measured 8 kilometres in diameter and 32 kilometres in length. The cylinders rotated to generate artificial gravity through centrifugal force.

The colony’s hull featured three sets of mirror panels that reflected sunlight into the habitat through massive windows. These windows alternated with three habitable land strips that ran the length of the cylinder. The land areas contained cities, parks, and other facilities to support the population.

Structure

A typical colony comprised several key sections:

  • Residential Block: The main living space along the colony walls, containing cities, infrastructure and public facilities
  • Agricultural Block: A separate rotating ring 32 kilometres in diameter optimised for farming
  • Industrial Block: Located in the colony’s central axis where microgravity conditions aided manufacturing
  • Spaceport: Docking facilities for ships located at the colony ends
  • Solar Power System: External mirror arrays to collect and direct sunlight

The counter-rotation of the paired cylinders cancelled out gyroscopic effects that would otherwise make it difficult to maintain the colony’s orientation toward the Sun. The rotation provided gravity equivalent to Earth normal at the cylinder walls.

Types

Several colony designs existed:

Island 1

  • 500 metre diameter sphere
  • Residential space along equatorial region
  • Example: Moon Moon colony

Island 2

  • 1.6 kilometre diameter sphere
  • Larger version of Island 1 design
  • Limited deployment

Island 3

  • Standard 8 × 32 kilometre cylinder design
  • Most common type by UC era
  • Used in all major Sides

Closed-type

  • Modified design without external windows
  • Higher population density
  • Used exclusively in Side 3

Colony clusters

Space colonies were organised into numbered clusters called Sides:

Space colonies grouped by Lagrange points:

Standalone colonies

Several independent colonies existed outside the main Sides:

  • Moon Moon: An Island 1 type colony that maintained an independent tribal society
  • Laplace: A Stanford torus that served as the Earth Federation government residence until its destruction in UC 0001
  • Hiland: A solar power satellite colony

Behind the scenes

The space colony designs in Mobile Suit Gundam were based on real proposals by physicist Gerard K. O’Neill in his 1976 book The High Frontier: Human Colonies in Space. The O’Neill cylinder concept influenced many subsequent science fiction works.

The series also accurately portrayed the Lagrange points as stable orbital positions, demonstrating the scientific research that went into the Universal Century setting.

Appearances

Television

Films

  • Mobile Suit Gundam: Char’s Counterattack
  • Mobile Suit Gundam: Hathaway