An artificial planet [1] (also known as a planetary replica or a replica planet) [2] is a proposed stellar megastructure. Its defining characteristic is that it has sufficient mass to generate its own gravity field that is strong enough to prevent atmosphere from escaping, [3] [4] although the term has been sometimes used to describe other types of megastructures that have self-sufficient ecosystems. [2] [5] The concept can be found in many works of science-fiction.
Mark Hempsell suggested that an artificial replica planet could be created in the Solar System as preparation for future space colonization, probably in the habitable zone between the orbits of Venus and Mars. It could evolve from the construction of a smaller space habitat. [1] [4] They would have similar purpose to other large scale megastructures intended as living spaces (such as O'Neill cylinder) or the concept of colonizing (or terraforming) existing planets. [3] [4] Unlike a space habitat, the artificial planet would be large enough to create its own gravity field that would prevent its atmosphere from escaping, and atmosphere would also serve to protect the world from radiation or meteorites. However, an artificial planet would have a much worse mass invested to usable surface area ratio. [4]
Material for artificial planet construction could be extracted from stars or gas giants [3] [4] or from asteroid mining. [2] A sufficiently advanced civilization could use those resources to mass-produce artificial planets using a stellar factory that itself would likely be the size of a large planet. [3] [4]
Construction of an artificial planet has been described as scientifically plausible but likely taking thousands of years and would be highly expensive. It has also been suggested that such an endeavour would be more challenging than terraforming existing planets, although both ideas are mostly speculative at this point of human history. [3]
The term artificial planet has also been used to describe other types of megastructures, such as large spherical space stations. [1] [2] D. R. Glover defined artificial planet as "a self-sufficient, independent ecosystem in space", noting that size of such an entity is less relevant and that it could be much smaller than what is traditionally defined as a planet. Glover sees development of such a station as a precursor step for development of ships capable of interstellar travel. [2]
Paul Birch has used this term to describe a concept of a supramundane planet. Such a structure would resemble the concept of a Dyson sphere, as the habitable surface would exist on the inner side, but it would be built around a massive stellar body, such as a giant planet or a black hole. [5] [6] [7]
The concept of artificial planet can be found in many works of science fiction. [4] An artificial planet is the main setting of several science fiction series, such as Philip José Farmer's Riverworld series (1971–1983), [8] Jack L. Chalker's Well World series (1977-2000) [9] and Paul J. McAuley's Confluence trilogy (1997-1999). [10] Iain Banks' novel Matter (2008) is set on a shellworld (an artificial planet with several habitable layers). [2] [11] [12]
The concept of artificial planets is also found in, among others, The Hitchhiker’s Guide to the Galaxy franchise created by Douglas Adams, where one of the characters is a "planet designer". [4] The Death Star from the Star Wars franchise has been called an artificial planet as well. [2] [13]
In the 2000 film Titan A.E. , a groundbreaking scientific project known as "The Titan Project", was designed to create new man-made, habitable planets in space.
A Dyson sphere is a hypothetical megastructure that encompasses a star and captures a large percentage of its solar power output. The concept is a thought experiment that attempts to imagine how a spacefaring civilization would meet its energy requirements once those requirements exceed what can be generated from the home planet's resources alone. Because only a tiny fraction of a star's energy emissions reaches the surface of any orbiting planet, building structures encircling a star would enable a civilization to harvest far more energy.
Terraforming or terraformation ("Earth-shaping") is the hypothetical process of deliberately modifying the atmosphere, temperature, surface topography or ecology of a planet, moon, or other body to be similar to the environment of Earth to make it habitable for humans to live on.
The Kardashev scale is a method of measuring a civilization's level of technological advancement based on the amount of energy it is capable of harnessing and using. The measure was proposed by Soviet astronomer Nikolai Kardashev (1932–2019) in 1964 and was named after him.
Star lifting is any of several hypothetical processes by which a sufficiently advanced civilization could remove a substantial portion of a star's matter which can then be re-purposed, while possibly optimizing the star's energy output and lifespan at the same time. The term appears to have been coined by David Criswell.
An Alderson disk is a hypothetical artificial astronomical megastructure, like Larry Niven's Ringworld and the Dyson sphere. The disk is a giant platter with a thickness of several thousand miles. The Sun rests in the hole at the center of the disk. The outer perimeter of an Alderson disk would be roughly equivalent to the orbit of Mars or Jupiter. According to the proposal, a sufficiently large disk would have a larger mass than its Sun.
A megastructure is a very large artificial object, although the limits of precisely how large vary considerably. Some apply the term to any especially large or tall building. Some sources define a megastructure as an enormous self-supporting artificial construct. 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. Typically these structures are at least 1,000 km (620 mi) in length—in other words, at least one megameter, hence the name. Such large-scale structures are termed megastructures.
In astronomy and astrobiology, the habitable zone (HZ), or more precisely the circumstellar habitable zone (CHZ), is the range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressure. The bounds of the HZ are based on Earth's position in the Solar System and the amount of radiant energy it receives from the Sun. Due to the importance of liquid water to Earth's biosphere, the nature of the HZ and the objects within it may be instrumental in determining the scope and distribution of planets capable of supporting Earth-like extraterrestrial life and intelligence.
Alan Bond is a British mechanical and aerospace engineer, who served as Managing Director of Reaction Engines Ltd and associated with Project Daedalus, Blue Streak missile, HOTOL, Reaction Engines Skylon and the Reaction Engines A2 hypersonic passenger aircraft.
An orbital ring is a concept of an artificial ring placed around a body and set rotating at such a rate that the apparent centrifugal force is large enough to counteract the force of gravity. For the Earth, the required speed is on the order of 10 km/sec, compared to a typical low Earth orbit velocity of 8 km/sec. The structure is intended to be used as a space station or as a planetary vehicle for very high-speed transportation or space launch.
Planetary habitability is the measure of a planet's or a natural satellite's potential to develop and maintain environments hospitable to life. Life may be generated directly on a planet or satellite endogenously or be transferred to it from another body, through a hypothetical process known as panspermia. Environments do not need to contain life to be considered habitable nor are accepted habitable zones (HZ) the only areas in which life might arise.
The colonization of Venus has been a subject of many works of science fiction since before the dawn of spaceflight, and is still discussed from both a fictional and a scientific standpoint. However, with the discovery of Venus's extremely hostile surface environment, attention has largely shifted towards the colonization of the Moon and Mars instead, with proposals for Venus focused on habitats floating in the upper-middle atmosphere and on terraforming.
The terraforming of Mars or the terraformation of Mars is a hypothetical procedure that would consist of a planetary engineering project or concurrent projects aspiring to transform Mars from a planet hostile to terrestrial life to one that could sustainably host humans and other lifeforms free of protection or mediation. The process would involve the modification of the planet's extant climate, atmosphere, and surface through a variety of resource-intensive initiatives, as well as the installation of a novel ecological system or systems.
The terraforming of Venus or the terraformation of Venus is the hypothetical process of engineering the global environment of the planet Venus in order to make it suitable for human habitation. Adjustments to the existing environment of Venus to support human life would require at least three major changes to the planet's atmosphere:
Paul Birch was a British author, engineer and scientist, who worked in radioastronomy and satellite communications, and latterly wrote full-time.
An Earth analog, also called an Earth analogue, Earth twin, or second Earth, is a planet or moon with environmental conditions similar to those found on Earth. The term Earth-like planet is also used, but this term may refer to any terrestrial planet.
Project Icarus is a theoretical engineering design study aimed at designing a credible, mainly nuclear fusion-based, unmanned interstellar space probe. Project Icarus was an initiative of members of the British Interplanetary Society (BIS) and the Tau Zero Foundation (TZF) started in 2009. The project was under the stewardship of Icarus Interstellar until 2019. It remains a BIS project.
Engineering on an astronomical scale, or astronomical engineering, i.e., engineering involving operations with whole astronomical objects, is a known theme in science fiction, as well as a matter of recent scientific research and exploratory engineering.
"Bigger Than Worlds" is an essay by the American science fiction writer Larry Niven. It was first published in March 1974 in Analog magazine, and has been anthologized in A Hole in Space (1974) and in Playgrounds of the Mind (1991). It reviews a number of proposals, not inconsistent with the known laws of physics, which have been made for habitable artificial astronomical megastructures.
A shellworld is any of several types of hypothetical megastructures:
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