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Megastructure

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A megastructure, in science fiction and speculative (or exploratory) engineering, is an enormous self-supporting artificial construct. The definition is often informal and varies from source to source, but generally requires at least one dimension to be in the hundreds of kilometers. Other criteria such as rigidity or contiguousness are sometimes also applied, so large clusters of associated smaller structures may or may not qualify. The products of megascale engineering or astroengineering are megastructures. Megastructures are sometimes also called megaprojects.

Megastructures are also an architectural concept popularized in the 1960s where a city could be encased in a single building, or a relatively small number of buildings interconnected together.

Megastructures often play a part in the plot or setting of science fiction movies and books.

Existing megastructures

There are structures on Earth that may be considered megastructures, such as

Networks of roads or railways, and collections of buildings (cities and associated suburbs), are usually not considered megastructures, despite frequently qualifying based on size. However, an ecumenopolis might qualify.

Proposed megastructures

Theoretical megastructures

Stellar scale

Most stellar scale Megastructure proposals are designs to make use of the energy from a sun-like star while possibly still providing gravity or other attributes that would make it attractive for an advanced civilization.

  • The Alderson disk is a theoretical structure in the shape of a disk, where the outer radius is equivalent to the orbit of Mars or Jupiter and the thickness is several thousand miles. A civilization could live on either side, held by the gravity of the disk and still receive sunlight from a star bobbing up and down in the middle of the disk.
  • A Dyson sphere (also known as a Dyson Shell) refers to a structure or mass of orbiting objects that completely surrounds a star to make full use of its solar energy.
  • Larry Niven's Ringworld is an artificial ring with a radius roughly equal to the radius of the Earth's orbit. A star is present in the center and the ring spins to provide artificial gravity.
  • An Orbital is a space habitat similar to but much smaller than a Niven Ring. Instead of being centered around a star, it is orbiting a star, thus its diameter is typically on the order of magnitude of a star. By giving a tilt to its orbit, there's a convenient day and night experience on its surface.
  • A Matrioshka brain is a collection of multiple Concentric Dyson Spheres which make use of different wavelengths of light.
  • A Stellar engine either uses the temperature difference between a star and interstellar space to extract energy or serves as a Shkadov thruster.

    • A Shkadov thruster accelerates an entire star through space by selectively reflecting or absorbing light on one side of it.
  • Topopolis (also known as Cosmic Spaghetti) is a large tube that rotates to provide artificial gravity.

Planetary scale

  • Globus Cassus is a hypothetical proposed project for the transformation of Planet Earth into a much bigger, hollow, artificial world with the ecosphere on its inner surface. This model serves as a tool to understand the World's real functioning processes.

Orbital structures

  • The Bernal sphere is a proposal for a space colony with a maximum diameter of 16 kilometers.
  • The Stanford torus is a different design with a diameter just under 1.7 kilometers.
  • The O'Neill cylinder is yet another space colony proposal.

Trans-orbital structures

  • A Skyhook is a very tall structure that hangs down from orbit.
  • A Space elevator is a skyhook that is fixed to the ground
  • A Space fountain is held up by the momentum of masses which are shot up to the top at high speeds from the ground.
  • A Lofstrom loop ("Launch loop") is a 2000km long iron loop that projects up in an arc to 80 km that is ridden by maglev cars while achieving orbital velocity.
  • Rotovator proposals call for a large tether to transfer momentum between spacecraft in transit.

Fictional megastructures

Stellar scale

  • The Dyson shell (including its variation, the Ringworld) has appeared in many works of fiction, including the Star Trek universe.
  • Larry Niven's series of novels about his Ringworld centered around, and originated the concept of the Ringworld, or Niven ring.
  • In the manga Blame! the Megastructure is a vast and chaotic complex of metal, concrete, stone, etc, that covers the Earth and assimilates the Moon.
  • In White Light by William Barton and Michael Capobianco, a Topopolis is presented as taking over the entire universe.
  • In the Heechee books by Frederik Pohl the race of pure energy beings called The Foe have constructed the Kugelblitz, a black hole made of energy and not matter.
  • In the Xeelee series of books by Stephen Baxter, the eponymous alien race constructed the Ring, a megastructure made of cosmic string, spanning over 10 million light years.

Planetary scale

Megascale structures

Structures that might not be classified as "Megastructures" because they do not meet the requirements, but are indeed "Mega" sized structures/constructions.

Stellar scale

See also

External links



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Last updated on Monday March 03, 2008 at 20:02:59 PST (GMT -0800)
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