Buzz
A megastructure represents the most monumental and costly human achievement. If you're a fan of science fiction, you're likely familiar with many of these concepts. For those less acquainted, these are captivating ideas that could one day become a reality. Feel free to share your personal favorites in the comments below.
10. Space Elevator
A space elevator is a proposed structure designed to transport materials from the surface of a celestial body into space. Various designs have been suggested, all based on traveling along a fixed structure rather than using rocket propulsion for launch. The most common version involves a structure extending from the Earth's surface near the Equator to geostationary orbit (GSO), with a counterweight beyond. Although current materials don't allow for such a structure, future advancements, such as carbon nanotubes, might provide the necessary strength.
9. Orbital Ring
An orbital ring is a variation of the space elevator concept, but this one orbits the Earth. In its most basic design, a rotating cable is placed in a low Earth orbit above the equator, rotating slightly faster than orbital speed. On this rotating ring, Ring Stations are electromagnetically suspended using superconducting magnets, and they remain fixed over specific locations on Earth. From these stations, shorter space elevators hang, built with cables made from materials known for their high tensile strength and low mass ratio.
8. Halo
Halos are fictional megastructures and superweapons featured in the Halo video game series. These immense ringworlds are equipped with their own ecosystems, including wildlife and weather. The design of the Halos mirrors Larry Niven’s Ringworld concept in both shape and structure. The exterior of the Halo installations is metallic, while the interior of the ring is filled with atmosphere, water, plants, and animals. A massive wall runs along the sides, and the centrifugal force generated by the ring’s rotation prevents the environment from spilling into space. Docking ports and windows appear on the exterior, suggesting that parts of the ring are hollow and used for maintenance, habitation, and power generation.
7. Globus Cassus
Globus Cassus is both an art project and a book by Swiss architect and artist Christian Waldvogel. It imagines the transformation of Earth into a vast, hollow, artificial world, with an ecosphere on its inner surface. This proposed megastructure would use all of Earth’s mass, with sunlight entering through two large windows. Gravity would be simulated by centrifugal force. Humans would live in two expansive regions that face each other, connected by the empty center. The hydrosphere and atmosphere would remain inside. The ecosphere would be concentrated around the equator, while the low-gravity tropics would only support plantations. The polar areas, lacking gravity and atmosphere, would be used for storing raw materials and conducting microgravity production.
6. Topopolis
A topopolis is a rotating, tube-shaped space habitat designed to generate gravity on its inner surface. It extends in a loop around the local star and can be wrapped multiple times in a geometric shape known as a torus knot. This concept was introduced by Pat Gunkel and later mentioned by Larry Niven in 'Bigger than Worlds.' Sometimes referred to as cosmic spaghetti, a typical topopolis could stretch for hundreds of millions of miles or kilometers and be several miles (or kilometers) in diameter.
5. Stellar Engine
Stellar engines are theoretical megastructures that harness the radiation from a star to generate usable energy. Some versions of these engines use this energy to produce thrust, effectively propelling the star and its orbiting bodies in a particular direction. The construction of such an engine would elevate its creators to the status of a Type-II civilization on the Kardashev scale, which measures a civilization's technological development. The three types of stellar engines are:
A class A stellar engine is a propulsion system for stars, consisting of a gigantic mirror or light sail — essentially a colossal solar statite so large it qualifies as a megastructure, potentially by an order of magnitude.
A class B stellar engine is a Dyson sphere (item 3), which captures the temperature difference between the star and the surrounding interstellar medium to extract usable energy from the system.
A class C stellar engine merges the features of the other two types, using the propulsion capabilities of the Shkadov thruster along with the energy generation functions of a Class B engine.
4. Matrioshka brain
This concept involves one or more Dyson spheres encircling a star, with each sphere nested within the other. A large portion of these shells would be made up of nanoscale computers, which would be partially powered by the energy transferred between the star and the interstellar medium. Each shell (or component, in the case of a Dyson swarm model) would capture the energy radiated onto its inner surface, use it to power its computers, and then radiate the energy back outward.
The optimal method for extracting usable energy as it travels 'through' a shell or component, how many shells (or orbital layers) could be supported in this manner, the ideal size of the shells, and various other considerations remain speculative topics of discussion.
While the concept of the matrioshka brain does not conflict with any known laws of physics, the engineering complexities involved in constructing such a structure would be immense. This project would likely necessitate the 'disassembly' of significant portions (if not all) of the star's planetary system to gather the necessary materials for its construction.
3. Ringworld
The Ringworld is an artificial megastructure with a radius similar to Earth's orbit around the Sun. At its center lies a star, and the ring spins to generate artificial gravity.
The mass of the Ringworld is said to be roughly equal to the combined mass of all the planets in our solar system. It is implied that its construction involved the complete consumption of the planets in the original system, down to the last asteroid and moon, as no other bodies orbit the Ringworld's star. In Ringworld's Children, it is further explained that the reaction mass required to accelerate the ring was about 20 times the mass of Jupiter. This suggests that either the original planetary system had a mass much larger than our solar system's or additional materials were used.
The creation of a Ringworld is purely speculative at this point. While such a structure could provide an immense habitable surface, the energy required to build it, get it rotating, and keep it stable is enormous—equivalent to several centuries of the Sun's total energy output. Without breakthrough energy sources yet to be discovered, it seems unlikely that such a project could ever be completed within a human lifetime.
2. Alderson disk
The Alderson disk, named after its creator Dan Alderson, is a colossal artificial structure, similar to Niven's Ringworld or a Dyson sphere. This disk, resembling a giant CD or phonograph record, spans several thousand miles in thickness. At the center lies the sun, and its outer radius would extend to approximately the orbit of Mars or Jupiter. The disk's mass would surpass that of its sun. However, one issue with this design is the lack of a day/night cycle, as the sun remains stationary, creating perpetual twilight. This could be resolved by making the sun move up and down within the disk, providing light to different sides alternately.
1. Dyson Sphere
A Dyson sphere is a theoretical megastructure first proposed by Freeman Dyson. It consists of a system of orbiting solar power satellites designed to completely surround a star and capture its energy output. Over time, other designs for similar structures, often referred to as Dyson spheres, have emerged, particularly in engineering concepts and science fiction. These proposals sometimes extend beyond power generation, incorporating elements for habitation or industry. Most fictional portrayals depict a solid shell surrounding the star, which is considered the least feasible design.
+ Atlantropa
Atlantropa, also known as Panropa, was an ambitious engineering and colonization plan proposed by German architect Herman Sörgel in the 1920s, which he promoted until his death in 1952. The utopian vision aimed to resolve Europe's major challenges by creating a new continent, 'Atlantropa,' merging Europe and Africa, which would be predominantly inhabited by Europeans. Sörgel believed that in order for Europe to remain competitive against the Americas and the rising power of Pan-Asia, it needed to be self-sufficient, which required colonizing Africa and securing territories in every climate zone.
The Atlantropa project failed to gain significant support due to its massive scale and Eurocentric expansionist ideals. During the Nazi era, the plan was dismissed as it conflicted with the idea of a Eurasian German Empire. The Italians rejected it as their cities relied heavily on coastlines. After World War II, interest briefly revived as Western powers sought closer ties with Africa and aimed to combat communism. However, with the advent of nuclear power, the high cost of rebuilding, and the decline of colonialism, Atlantropa became technologically irrelevant and politically unfeasible, though the Atlantropa Institute continued to exist until 1960.
