A megastructure, in science fiction and speculative (or exploratory) engineering, is an enormous self-supporting artificial construct. Exploratory engineering is a term coined by K Eric Drexler to describe the process of designing and analyzing detailed hypothetical models of systems that are not feasible with 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. Megascale engineering is a form of Exploratory engineering concerned with the construction of structures on an enormous scale Astroengineering is the construction of Megastructures in space by technologically advanced beings

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 are an Architectural concept popularized in the 1960s where a city could be encased in a single Building, or a relatively small number of buildings The term architecture (from Greek αρχιτεκτονικήarchitektoniki) can be used to mean a process a profession or documentation

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

Existing megastructures

The Great Wall of China is an example of a megastructure. The Great Wall of China ( or ( is a series of stone and earthen Fortifications in China, built rebuilt and maintained between the 6th century BC and the 16th This picture was taken near Beijing in winter.

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

• The Great Wall of China is a human-built megastructure, a few meters wide and 3,947 mi (6,352 km) in length, about 4,975,318 square yards (4,160,000 m²)

• The Rice Terraces of the Philippine Cordilleras, a 10,360 square kilometer (4,000 square mile) sprawling agricultural landscape carved in the mountains by free tribesmen of Ifugao some 6,000 to 2,000 years ago. The Great Wall of China ( or ( is a series of stone and earthen Fortifications in China, built rebuilt and maintained between the 6th century BC and the 16th To aid in the comparison of sizes of different geographic regions areas between 1  Km² (100 Hectares and 10 km² (1000 hectares are listed below M^2 redirects here For other uses see M². CM2 redirects here The Banaue Rice Terraces (Hagdan-hagdang Palayan ng Banaue are 2000-year old terraces that were carved into the mountains of Ifugao in the Philippines

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. Ecumenopolis (from οικουμένη meaning world and πόλις ( Polis) meaning city thus a city made of the whole world; pl

Proposed megastructures

• Atlantropa, a hydroelectric dam to be built across the Strait of Gibraltar, and the lowering of the surface of the Mediterranean Sea by as much as 200 metres. Atlantropa was a gigantic engineering and colonization project devised by the German Architect Herman Sörgel in the 1920s and propagated by Hydroelectricity is electricity generated by Hydropower, ie the production of power through use of the gravitational force of falling water The Strait of Gibraltar ( Arabic: مضيق جبل طارق Spanish: Estrecho de Gibraltar) is the Strait that connects the Atlantic

Theoretical megastructures

Stellar scale

A cut-away diagram of an idealized Dyson shell—a variant on Dyson's original concept—1 AU in radius. A Dyson sphere (or shell as it appeared in the original paper is a hypothetical Megastructure originally described by Freeman Dyson. The astronomical unit ( AU or au or au or sometimes ua) is a unit of Length based on the distance from the Earth to the

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. An Alderson disk (named after Dan Alderson, its originator is an artificial astronomical Megastructure, like Niven 's Ringworld 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. A Dyson sphere (or shell as it appeared in the original paper is a hypothetical Megastructure originally described by Freeman Dyson. A Dyson sphere (or shell as it appeared in the original paper is a hypothetical Megastructure originally described by Freeman Dyson.
• Larry Niven's Ringworld is an artificial ring with a radius roughly equal to the radius of the Earth's orbit. Ringworld is a Hugo and Nebula award-winning 1970 Science fiction novel by Larry Niven, set in his Known Space 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. In Iain M Banks ' fictional Culture universe an Orbital (sometimes also simply called an O or a small ring) is a purpose-built 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. An order of magnitude is the class of scale or magnitude of any amount where each class contains values of a fixed ratio to the class preceding it 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 matrioshka brain is a hypothetical Megastructure, based on the Dyson sphere, of immense computational capacity Concentric objects share the same center, axis or origin with one inside the other
• A Stellar engine either uses the temperature difference between a star and interstellar space to extract energy or serves as a Shkadov thruster. Stellar engines are a class of hypothetical Megastructures which use a star's radiation to create usable energy Stellar engines are a class of hypothetical Megastructures which use a star's radiation to create usable energy
  • A Shkadov thruster accelerates an entire star through space by selectively reflecting or absorbing light on one side of it. Stellar engines are a class of hypothetical Megastructures which use a star's radiation to create usable energy
• Topopolis (also known as Cosmic Spaghetti) is a large tube that rotates to provide artificial gravity. A topopolis is a tube-like space habitat rotating to produce gravity on the inner surface which is extended into a loop around the local star

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. Globus Cassus is an art project and book by Swiss architect and artist Christian Waldvogel presenting a conceptual transformation of Planet Earth into a much bigger hollow 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. A Bernal sphere is a type of space habitat intended as a long-term home for permanent residents first proposed in 1929 by John Desmond Bernal.
• The Stanford torus is a different design with a diameter just under 1. The Stanford torus is a proposed design for a Space habitat capable of housing approximately 10000 to 140000 permanent residents 7 kilometers.
• The O'Neill cylinder is yet another space colony proposal. The O'Neill cylinder also called Island Three is a Space habitat design proposed by physicist Gerard K

Trans-orbital structures

One concept for the space elevator has it tethered to a mobile seagoing platform. A space elevator is a proposed structure designed to transport Material from a celestial body 's Surface into space.

Main article: Non-rocket spacelaunch

• A Skyhook is a very tall structure that hangs down from orbit. Non-rocket spacelaunch (NRS is the idea of reaching outer space specifically from the Earth's surface predominately without the use of conventional chemical rockets which today Skyhooks are a type of hypothetical structure that would be used for Non-rocket spacelaunch into Orbit, for example a Space elevator, continuously supporting
• 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 space elevator is a proposed structure designed to transport Material from a celestial body 's Surface into space. A space fountain is a proposed form of Space elevator that does not require the structure to be in Geosynchronous orbit, and does not rely on Tensile strength
• 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. A launch loop or Lofstrom loop is a design for a belt based Maglev Orbital launch system that would be around 2000 km long and maintained at Magnetic levitation, maglev, or magnetic suspension is a method by which an object is suspended with no support other than Magnetic fields The
• Rotovator proposals call for a large tether to transfer momentum between spacecraft in transit. Tether propulsion systems are proposals to use long very strong cables (known as Tethers to change the velocity of Spacecraft.

Fictional megastructures

Stellar scale

• The Dyson shell (including its variation, the Ringworld) has appeared in many works of fiction, including the Star Trek universe. A Dyson sphere (or shell as it appeared in the original paper is a hypothetical Megastructure originally described by Freeman Dyson.
• Larry Niven's series of novels about his Ringworld centered around, and originated the concept of the Ringworld, or Niven ring. Laurence van Cott Niven (born April 30, 1938 Los Angeles California) is a US Science fiction author. Ringworld is a Hugo and Nebula award-winning 1970 Science fiction novel by Larry Niven, set in his Known Space Ringworld is a Hugo and Nebula award-winning 1970 Science fiction novel by Larry Niven, set in his Known Space
• 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. ˈmɑŋgə is the Japanese word for Comics (sometimes called komikku コミック and print Cartoons In their modern form manga date from shortly is a ten-volume Cyberpunk Manga by Tsutomu Nihei. The tagline for this manga is "Adventure-seeker Killy in the Cyber Dungeon quest!" or
• In White Light by William Barton and Michael Capobianco, a Topopolis is presented as taking over the entire universe. William Renald Barton III (born September 28 1950) is an American Science fiction writer Michael Victor Capobianco (born November 12, 1950) is an American Science fiction writer A topopolis is a tube-like space habitat rotating to produce gravity on the inner surface which is extended into a loop around the local star
• 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. The Heechee are a fictional alien race from the Science fiction works of Frederik Pohl. Frederik George Pohl Jr (born November 26, 1919) is a American Science fiction writer, editor and fan, with a career
• 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. This article details the various alien races and human offshots present in Stephen Baxter's Xeelee Sequence of future history Stephen Baxter (born 13 November 1957 is a British Hard science fiction Author. A cosmic string is a hypothetical 1-dimensional (spatially Topological defect in various fields
• In the game Airforce Delta Strike a large Space Elevator called the Chiron Lift is used to send supplies out into outer space. Airforce Delta Strike, known as Airforce Delta Blue Wing Knights in Japan and Deadly Skies III in Europe is the third Later in the game it is destroyed by an artificially enhanced human named Pierre who fights for the Orbital Citizens Community (OCC).

Planetary scale

Delta Halo, One of the 7 Halos from the Halo universe

• Death Star of Star Wars fame
• Borg Transwarp Hub and Unicomplexes, Federation Starbases and Fleet Yards
• Buster Machine III from Gunbuster. Halos are fictional Megastructures and Superweapons in the Halo video game series The Death Star is a Fictional Space station and Superweapon appearing in the Star Wars movies and expanded universe. Star Wars is an epic Space opera franchise initially conceived by George Lucas during the 1970s and significantly expanded The Borg are a fictional pseudo- race of Cyborgs depicted in the Star Trek franchise The United Federation of Planets, (also known as the "The Federation" or UFP) is a fictional interplanetary state depicted in the Star Trek Buster Machine III (バスターマシン三号） also known as the Black Hole Bomb （ブラックホール爆弾） is a Superweapon of Megastructure Gunbuster, known in Japan as is a six episode Anime OVA series created by Gainax in 1988
• Culture Orbital
• Trantor, the capital of an interstellar empire in Isaac Asimov's Foundation series, is a planet entirely covered in one huge metal clad building, with only one small green space: the Emperor's palace grounds
• Coruscant, capital city in the Star Wars universe, entirely covers its host planet. In Iain M Banks ' fictional Culture universe an Orbital (sometimes also simply called an O or a small ring) is a purpose-built Star Wars is an epic Space opera franchise initially conceived by George Lucas during the 1970s and significantly expanded It serves as capital of first the Republic and then later the First Galactic Empire.
• The Ori Supergate seen in a number of episodes of Stargate SG1 could be classed as a megastructure
• In The Hitchhiker's Guide to the Galaxy series, Earth, as well as other planets, were artificial megastructures. The Ori (ɒrаɪ The Ori fabricated a religion called Origin which they use to control non-ascended beings attempting to destroy anyone who rejects it A Stargate is fictional device that allows practical rapid travel between two distant locations The Hitchhiker's Guide to the Galaxy is a science fiction comedy series Earth was intended to function as a gigantic computer, and was built by a race of beings who made their living by manufacturing other planets.
• The Star Forge from Knights of the Old Republic
• Despite being sentient, the Transformers universes Unicron's 'metal planet' form is comparable to a megastructure. A transformer is a device that transfers Electrical energy from one circuit to another through inductively coupled Electrical conductors Unicron is a Fictional character from the ''Transformers'' universe and toyline.
• The seven Halos from the Halo universe are 10,000 km wide rings. Halos are fictional Megastructures and Superweapons in the Halo video game series Halo is a Science fiction Video game franchise created by Bungie and owned and published by Microsoft Game Studios.
• In the Robotech Sentinels novels, Haydon IV is an artificially constructed cyber-planet with android citizens. Robotech is a Science fiction franchise that was launched by an 85-episode adaptation of three different Anime Television series.
• In the Invader Zim episode "Planet Jackers", two aliens surround the Earth with a fake sky in order to throw it into their sun. Invader Zim, Branded as Invader ZIM, is an American Animated television series that was produced by and subsequently This is a list of episodes for Nickelodeon's Animated television series Invader Zim.
• Nightmare's fortress from Kirby: Right Back at Ya! can be classified as a megastructure because of the fact that it's the size of a small planet. Kirby Right Back At Ya!, known in Japan as, is an Anime series based on Nintendo 's Kirby franchise
• In several works, Arthur C. Clarke writes about a colossal hollow tube, first described in "Rendezvous with Rama" (1973), and inhabited by different races. This article is still a work-in-progress the main body is not yet intact Rendezvous with Rama is a novel by Arthur C Clarke first published in 1972.

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

• Dyson Bubble - Collection of separate constructions. A Dyson sphere (or shell as it appeared in the original paper is a hypothetical Megastructure originally described by Freeman Dyson.
• Dyson Swarm - Collection of separate constructions. A Dyson sphere (or shell as it appeared in the original paper is a hypothetical Megastructure originally described by Freeman Dyson.

See also

• Supertall
• Arcology
• Megaproject

External links

• Megastructures in science fiction index by Ross Smith. While determining the world's tallest structure has generally been straightforward the definition of the world's tallest building or the There is some dispute over whether this article should document both the meaning of this term as used in popular fiction as well as its technical meaning in the field of architecture or A megaproject is an extremely large-scale Investment Project.