I started by researching these hypothetical Mega-structures that would be built deep in space and came up with quite a few examples.
A construct that covers or surrounds a star in order to capture the power output, a concept talked about by Freeman Dyson in his 1960 paper ‘Search for Artificial Stellar Sources of Infrared Radiation’. He theorised that in order to meet the rising energy demands of a highly advanced race, they would have to capture most of or all of the power output of a sun, following this are a few different constructs that might accomplish such a task.
Dyson Shells, as seen in the cover photo and below, are massive hollow spheres that completely encompass a star in order to capture the stars entire output of energy, this would be the mostly costly of all these methods as the Shell would have to extend to further than Earths orbit in order to function properly.
An example of this in fiction would be the Star Trek: Next Generation episode ‘Relics’, in which the crew of the Enterprise discovers an immense Dyson Shell with the inside wall covered in habitable areas and ambient atmosphere.
Credit of the cover photo to Danielle Futselaar
A large ring of individual constructs orbiting a star to collect the power output, while not as effective as a Shell, it would be vastly cheaper and require significantly less materials to produce.
Much like a Ring but on a huger scale, this would include multiple rings all orbiting a star in very complex orbital paths, the orbits would have to be worked out carefully in order to make sure there are no collisions between structures and to prevent them eclipsing each other.
It’s been speculated that a Dyson Swarm is being built right now around a star designated ‘KIC8462852’ and nicknamed ‘Tabby’s Star’. This star has recently had it’s light output reduced by 22% as if there is a large number of objects between it and the Earth, while it has been dismissed by most as just a “uneven ring of dust” a few still believe that there is an advanced race of alien creatures building a Dyson Swarm around it.
This collection of constructs is much like a Swarm, but instead of hundreds of constructs in a tight orbit these are completely stationary which vastly reduces the risk of collisions and eclipsing.
A tube like habitat looped around a star, sometimes one may be looped several times in a figure called a Torus Knot, because of this a Topopolis is sometimes referred to as “Cosmic Spaghetti”. This tube would be rotating to provide artificial gravity by centrifugal force to people would be able to live on the inside walls, a typical Topopolis would be hundreds or millions of miles long and several miles in diameter. This concept was invented by Patrick Gunkel and mentioned by Larry Niven in his essay ‘Bigger than Worlds’.
A good example of a Topopolis in fiction would be in the novel ‘Matter’ by Iain M. Banks in which a Topopolis is looped many times around a sun in various patterns and figures, the habitat houses trillions of sapient residents and is described as having a “Haze” between each braid due to stray gases being collected and forming a slight atmosphere.
Much like a Topopolis but instead of a large loop, this consists of two counter rotating cylinders in order to counter gyroscopic effects that make it difficult to keep them aimed at a star. Each cylinder would have to be about 20 miles long and 5 miles in diameter, people would live on the inside surface of the tube just like they would in a Topopolis.
Gerard K. O’Neill proposed this concept in his 1976 book ‘The Higher Frontier: Human Colonies In Space’, however a similar idea of using rotating cylinders in space was described by Hermann Oberth in his book ‘Menschen im Weltraum – Neue Projekte für Raketen- und Raumfahrt’ or in English ‘People in space – New projects for rockets and space travel’.
An immense disc several thousand miles thick with a perimeter that would reach about Mar’s or Jupiter’s orbit, a star would sit in a hole in the middle of the disc, the disc itself would have a much higher mass than the actual star it surrounds, because of how big this structure would be it would take more resources than is in our solar system in order to create it, maybe even 3 or 4.
Due to the sun’s position in the disc, each side would be habitable but would also be bathed in perceptual twilight, this can be rectified by somehow making the sun bob up and down in order to light one side then the other. The disc would need high retention walls on the inner rim of the disc to stop the atmosphere just drifting into the sun. The habitable zone on the disc would be relatively small compared with the entire size of the disc, too close the the centre of the disc would be a scorched arid zone unsuitable for habitation and vice versa for the outside edges of the disc. It’s been theorised by Larry Niven that while we can live on a small ring on the disc, alien creatures from hotter or cold planets could share the disc and live either side of our zones.
A popular example of this in fiction is ‘The Godwheel’, a feature in Malibu Comics where one side of this disc is inhabited by magic using medieval people and the other by a technologically advanced civilisation.
This Mega-structure is shaped like a ring, as proposed by Forrest Bishop in 1997 and Larry Niven in 1970. This structure forgoes being enclosed as due to the immense nature of it and the centrifugal force created by it’s spinning, though hypothetically it would need walls of over 100 miles in height to retain it’s atmosphere.
This is a popular concept in fiction and was probably first used by Larry Niven in his 1970 novel ‘Ringworld’, in which exists a habitable ring called ‘Ringworld’. This ring includes Earth like habitable conditions and has everything from mountain ranges to oceans in it’s almost 100, 000 mile width and 600,000,000 mile circumference. Due to ‘Ringworld’ being built around a sun, one would have to implement some kind of day and night cycle, they do this by having and inner ring of “shadow squares” orbiting the sun in a tighter orbit, these are strung together but thin but ultra strong wire and cast shadows over ‘Ringworld’. The ring is inhabited by primitive people that live in the ruined cities of a once advanced civilisation.
Other Great Examples
As one of my most favourite game series, I’ve spent many an hour playing Mass Effect, not really thinking much about the giant constructs within the game but now I look back, I can marvel at how well these concepts were portrayed.
The Citadel is a massive space station consisting of spinning enclosed ring with 5 flat long rectangles extruding from it all facing inwards to each other, due to the centrifugal force sentient races can live on the inside of this ring and the wings. The central ring is called the Presidium and is generally where the upper class and ambassadors from each race can live and work, the wings house the Wards where the working class live and shop, this includes docks for space craft and all sorts of stores. The Citadel is tended by ancient creatures called Keepers, nobody knows anything about them due to their tendency to self destruct if anyone tries to examine them.
Also in the Mass Effect universe is the Mass Relays, massive constructs that act as gateways to other parts of the Milky Way, they are the prime method of travel and save time in travelling from system to system even when Fast Than Light travel is used.
The Halo series is set mostly around ancient Mega-structures created by an ancient extinct race of aliens called the ‘Forerunners’, all discovered “Installations” are generally used for containment of dangerous lifeforms.
The namesake of the games, the Halo Installations are giant Niven Rings inspired by ‘Ringworld’ that were built to contain and study an incredibly dangerous parasitic life form called the ‘Flood’, this life form infects alien species to take control of them and is almost unstoppable. The Halo rings also act as a super weapon that destroys all biological life in the event that the Flood were to escape their prison.
The Forerunners also built a planet sized prison called ‘Requiem’, essentially a Micro Dyson Sphere, this planet contains a few layers between the prison and space. The first layer is a giant metal shell that completely contains the planet and simulates light and atmosphere for the second layer. The second layer is just the normal planet surface, however the planet also happens to be hollow, containing the prison right in the centre of itself. The prison in question contains one of their own, a Forerunner criminal named Ur-Didact whom due to the suspended animation of his prison, the Cryptum, comes back in Halo 4 and is the main antagonist for that game. Requiem is an installation called a Shield World, also known as “Shield 0001” and the “Legendary Planet”.
While technically cheating, I still feel like this should be mentioned.
Swimming endlessly through space is the Great A’Tuin the Turtle, standing upon his back are four Elephants, Berilia, Tubul, Great T’phon and Jerakeen, resting upon their shoulders is the Discworld, a giant disc roughly 10,000 miles wide with an estimated population of 20,000,000. The disc is a fully functioning world complete with everything a normal planet would have, cities, mountain ranges, seas and talking trees, the seas flow off the edge of the disc as what is known as the “Rimfall”. The Sun and Moon of Discworld were first described as 1 mile in diameter which later changed to 80 miles, both orbit Great A’Tuin and it’s said that one of the Elephants has to cock it’s leg in order for the sun to continue on it’s path.
The whole of Discworld is covered in a magical field that makes magic possible within it’s boundaries but also slows light down from millions of miles per hour to hundreds, It’s described as being lazy. Great A’Tuin also takes on the role of protecting Discworld from collisions of asteroids by rolling on his back or swatting them out of his way.