One-Product Planet

In the Standard Sci Fi Setting, trade is common between star systems. Sometimes to survive, a planet becomes so specialized that focuses on a certain commodity or service. Maybe its building weapons or providing doctors. Whatever it is, the world trades this resource with other planets, becoming renowned for the export.

This trope isn't about a single Planetville; It focuses on the big picture on how individual worlds interact with each other. Subtrope of Planet of Hats, though any location (an asteroid, small moon, space colony) can serve as this. Compare/Contrast Single Biome Planet.

Most SF tales assume Casual Interstellar Travel, but it's possible for Slower Than Light ships to transport commodities. But the items being traded would be of extreme value to justify the high cost and long wait.

Economics aside, a planet has other values: political, cultural, religious, and military. The importance of the export directly influences the importance of the planet. For example, the Planet of Phlebotinum would have a lot of power and an armada protecting it. However, the Planet of Toasters would lack any economic influence and maybe warrants a corvette for protection. Meanwhile, the Planet of Judges Robes and Powdered Wigs would have political clout, but lack economic influence. The amount of protection relies on how much influence they have with their neighbors.

May correlate with Multipurpose Monocultured Crop, if the One Product is farmed instead of manufactured.

Primary Locations

 * Big Dumb Object: Artifact of Precursors, often a massive construct such as a Dyson Sphere or ringworld. Or recently made by a highly advanced civilization. Can be visited by intrepid explorers and researchers to produce Lost Technology. There is a disturbing trend for BDO's to be abandoned, acting as prisons for alien viruses, which are accidentally released by said explorers.


 * Capital: Political center of an interstellar government and a place of intrigue. Represents the height of culture and power, as well as decadence and corruption. Highly valued, expect the world to be well protected...unless no ships are available for whatever reason. Capitals of various space Empires tend to be highly urbanized.


 * Factory: Center of mass production. Presented as industrial nightmares, with polluted skies and crowded cities. Its products can include technology, but often less state-of-the-art. Such worlds are focused on production/engineering than research.


 * Farms: Focuses on growing crops and raising animals. There are typically two types:
 * Worlds that only produce foodstuffs to feed places that can't produce enough subsistence, such as urbanized worlds or space stations. Not much value, except if the importer is totally dependent on them. Then the planet becomes an Achilles' Heel. Often rural in nature, but hydroponic bays and protein vats are not unheard of.
 * Worlds which harvest an important crop that has unique attributes. Such flora or fauna could be used for medicinal uses, especially if it's a drug. Then it would be more profitable than a world that exports beef. Such farms tend to be jungle or death worlds.


 * Forbidden: Location of dangerous nature that no one visits. Could be a colony ravaged by plague or infested by alien locusts. Whatever the reason, the planet is no longer of any value, covered in ruins or wasteland. Only adventurers would willingly travel to these worlds.


 * Gates: Point or area where a wormhole/ stargate/ minimum hyperlimit that allows FTL transport. Vital for rapid transport (unless you want to slog decades across space), and in the cases of a Portal Network, act as a chokepoint.


 * Exotic: Offers scientific curiosities and unusual matter (monopoles, antimatter, mini black holes), or a site of strange astronomical happenings (such as wormholes or black holes). If extra-terrestrial life is rare, then worlds with alien biospheres would be of interest. Scientists and corporations would love samples of strange matter, or get a chance to observe such strange phenomenon.


 * Library: Structure that houses a huge database of the knowledge of an entire civilization. Many researchers visit here to learn from the accumulated knowledge. Often left behind by Precursors, though such projects are undertaken by more recent societies as a prestigious project. Expect it to be very quiet and vast.


 * Military: Main export is military forces (often as Mercenaries), coming in two varieties:
 * Super Soldiers, often living in a military culture and/or harsh environment to develop their skills.
 * Cannon Fodder, hired out only because the planet has nothing else to sell.
 * Along with these, various settings have their armies are specializing on an armed branch: armour warfare, Special Ops, sapping, urban warfare, etc. Life on these worlds tend to be tough.


 * Mines: Areas that harvest important natural resources. Often its rare metals, or minerals and gases needed for maintaining various ships and machines. How important and powerful a Mine is depends on how vital the resources its gathering. A world mining Tin isn't going to be much value. However, a world collecting Helium-3 (which can be used for fusion reactors) are going to be richer and better protected. Such places can range from terrestrial planets to asteroids to gas giants.


 * New World: Planet that is newly discovered and open for grabs. Expect new settlers or folks fighting over the planet. Such worlds would have little to export and much to import, due to a lack of infrastructure. If settled, frontier towns are likely.


 * Penal Colony: Dumping grounds for criminals or "discontents". Expect these worlds to be unpleasant at the very least. Penal colonies can range from orderly communities to work camps to Mad Max wastelands. If these worlds export anything, it's likely products of slave labor.


 * Phlebotinum Monopoly: When there's only one source of Immortality Drugs, Dilithium Crystals or Spice, and everybody needs it. Whoever controls this world can control the galaxy. Anticipate this world to warrant fleets or warships and armies to protect it, and many fights over it.


 * Pleasure Planet: Places for tourists to visit and relax, often paradise worlds or something akin to Las Vegas in space. Mostly, it is a place for the protagonists to relax, especially if there's beaches. Not likely to be a major target, unless it's a strategic location or attacked for symbolic reasons.


 * Science: Known for its research and development, and its state-of-the-art technology. Expect these worlds to value logic and headed by technocrats. Home to a lot of cool gadgets, new technology, and various scientists (mad or otherwise).


 * Service: Instead of producing goods, these worlds focus on training and providing professional help. Common in SF are:
 * Medical: Professionals devoted to healing others in body and mind. Includes Doctors and Psychologists.
 * Education: Known for their universities and training centers.
 * Financial: People who work with money, including loaning, banking, trading, escrow agencies, etc.
 * Other services can include lawyers, intelligence agents, engineers, beauticians, etc. May also produce items of great importance to these services, such as instruments if the planet is known for its musicians.


 * Shipyards: Places devoted to building spacecraft. Since ships are vital to an interstellar empire, the yards are vital industries and military assets. Often military/government operated.


 * Superweapon: A planet or station where a Weapon of Really Mass Destruction is housed. Whoever controls the superweapon can decide the fate of the galaxy. In Space Opera, this is the site of a climactic battle.


 * Underworlds: Planet notable for its black market products and services. With enough money, one can hire thieves, smugglers, and assassins. Otherwise, one can purchase slaves, illegal technology, and other contraband. The items provided by an Underworld need not be illegal, but merely taboo. Such locations are commonly seedy and ruled by those in the shadows.

Modifiers
In addition to the above types, there are several attributes that can affect the value of a world.


 * Alien: Worlds or stations inhabited by Intelligent Extra-terrestrials. An important term for emerging space societies or where life is rare.


 * Blockaded: Planet that is prohibited from trade, often with an enemy fleet enforcing the embargo. Smugglers and rebels would try to get pass the blockade for various reasons.


 * Cultural Center: Major center of arts and learning, valued for its impact on society. Often focusing on the arts and entertainment.


 * Developing: Planet whose technology or infrastructure is lagging. Part of the Interstellar culture and trade, but often less advanced than the major powers. Except these planets to be impoverished, often new colonies or exploited conquests. Between the major powers, the Developing worlds would be caught between political struggles.


 * Dying: Planet that had seen better days, and is now waning. They may have been over exploited and depleted of primary resources or undergoing a natural calamity. These planets tend to collect garbage, both physical artifacts and the seedier elements of society.


 * Habitable: Planet can support human life, or whatever species the protagonists are. Can range from Edens to barely habitable death worlds. In a setting were most planets are dead or uninhabitable (say Real Life), a planet with a breathable atmosphere is better than nothing.


 * Homeworld: Planet was a species originated from. A lot of historical and religious importance, because of its mystique of being where a species is born. The dominant species of an Empire will have their homeworld as a Primary Capital, although there are exceptions. The destruction of a Homeworld is often a major mistake for space tyrants: it not only crosses the line, but ensures that a native of that world would eventually destroy said tyrant.


 * Historical Center: Location of past importance, such as a battle. Often archaeological sites or monuments are located here. Because of its Historical status, these places are seen as important symbols. For example: a dead moon may have little or no value, but military commanders may make choose to fight there since it was the site of a previous victory.


 * Holy Center: Place of major importance to a religion, often attracting pilgrims or a place of worship. If the religion is benign, attacking this center is a sign that you're an evil jackass. More fanatical sects would protect these centers.


 * Primitive: Planet with little or no high technology or advancements. Any inhabitants are either aliens developing civilization or the remnants of a failed colony. Expect wilderness and perhaps alien ruins. Any interest to these worlds are either for Science or Strategic.


 * Strategic: A system whose location is makes it a vital military target. Expect military fleets and fortresses here.

Anime and Manga

 * Crest of the Stars / Banner of the Stars: Interstellar travel relies heavily on Gates. During Jinto's and Lafiel's adventures, they visit a Factory asteroid (producing Antimatter), a Strategic planet, help enforce a planetary Blockade, and latter coming across a rather civilized Penal world.
 * Mobile Suit Gundam SEED: ZAFT's colonies were arranged in this manner, with one group focusing on Farming, another on Information Science, another on Chemistry, and so on.

Film

 * Avatar: An example of interstellar commerce with STL craft. Pandora is mostly valued for its Phlebotinum Monopoly, though having a Exotic Alien society and ecosystem.
 * Star Wars: As with any good space opera, Star Wars provides plenty of examples. Coruscant is a Capital, Bespin and Kessel are Mines, Endor houses a Superweapon, the First Death Star itself was a Superweapon, Genosis is a Factory world, Tatooine is a minor Underworld, and Yavin and Hoth were strategic locations. Naboo was Blockaded for a while.
 * Spoofed in Stingray Sam with Durango, a Planet of Rocket Builders which after an economic slump turns into a Planet of Criminals and then a Planet of Prison Factories (in which they build rockets).

Literature

 * Childe Cycle: The interstellar economy depends on specialized services, almost to the point of Crippling Overspecialization. Dorsai and the Friendlies provide Military, Ste. Marie focuses on Farming, the Exotics on Health Services, Coby on Mining, Newton and Venus on Science, Ceta on Commercial Services, Cassdia on providing Technical Services as well as mercs. Zombri, otherwise an uninhabited world, is a Strategic location.
 * CoDominium: Alderson Points serve as Gates. During the CoDO era, most worlds were used as Mines, Drug Farms, and Penal Colonies. Many industrialized worlds hired out Military forces as mercs. Latter, more examples, such as Pleasure and Alien worlds begin to appear.
 * Con Sentiency: With the development of Jumpdoors (acting as Gates), traveling between the stars is so causal there a planet devoted to a single service: Beautician worlds, Honeymoon Worlds, even Gynecologist Worlds. Dosadi is part Penal and part Science World, where every inhabitant is part of a massive experiment.
 * Cordwainer Smith: In his Instrumentality milieu, Norstrilia is a Farm World with a Phlebotinum Monopoly, making it extremely rich and envied. Viola Siderea is an Underworld, a planet of thieves. Shayol serves as a Penal world of the Body Horror kind.
 * Parodied in The Didactics of Mystique, a takeoff on The Tactics of Mistake. Interstellar civilization is falling apart because each world offers only one profession, and there are far less inhabited worlds than needed professions.
 * Dune: the titular planet is a Phlebotinum Monopoly, with Giedi Prime a Factory world, Ix and Richese a Science worlds, Telixau as a Underworld, Caladan is a Farm world, Kaitain is the Captial, Salusa Secundus is ostensibly a Penal colony but really a Military world. Tupile is a Service world, providing protection for exiled families.
 * Foundation: Trantor is the Capital, the Foundation serves as Science/Library as well as another Capital. Many other planets are Developing/Strategic due to their location and influence, as well as Mines. Pleasure and Farm worlds are also mentioned.
 * Gaunt's Ghosts: The forest planet Tanith was, when it still existed, a major exporter of high-quality wood.
 * Hammers Slammers: Several Farms and Mining Worlds were apparently set up this way so new colonies couldn't become economically independent. Occasionally, the protagonists end up fighting in Big Dumb Objects or against Aliens.
 * Hitch Hikers Guide to The Galaxy, to the point that some planets now have commodities growing naturally on them such as a swamp planet with mattresses that get slaughtered and dried to be slept on. Another planet has tools that grow on trees.
 * The Hunger Games: Districts in the series function like this. Each has one and only one job to do (such as District 12: coal mining, or District 11: agriculture), all of which support the Capitol.
 * A Planet Called Treason: Variant of this trope on a planetary level, where each Region on the planet are Service providers, specializing in different areas: Biology, Theology, Genetic Engineering, and Acting, to name a few.
 * In Honor Harrington, The Manticore System serves as a Gate, housing the Manticore Wormhole Junction which provides Manticore with a lot of economic clout.
 * During the war with Haven Trevor's Star serves as Strategic since its holds a Junction Terminus that would allow Haven access to the Manitcore system. It's also becoming the Capital World of the burgeoning Star Empire of Manticore.
 * Beowulf in Sigma Draconis is a Science World, noted for being the galaxy wide leader in (ethical) biomedical and genetic research. Given recent developments in the series, it may also become Strategic as well since if also hosts the one end of the Manticore Wormhole.
 * Retief has the CDT sent on various Alien/Developing worlds, often trying negotiate with the natives. Such worlds are often caught between the cold war of the CDT and the Groaci, who vie for political influence.
 * In the Vorkosigan Saga Komarr serves as both Gate and Strategic for Barrayar since it contains the wormhole route that is the only connection that Barrayar has to the rest of the galaxy. The Hegen Hub is a more general Gate. Beta Colony is Science (of almost all varieties), Jackson's Whole is Underworld Service and Earth is Cultural Capital.
 * Sometimes the specialization is stated more in terms of species than of planets. In Star Guard by Andre Norton, Earth, a poor backwater latecomer to a galactic civilization, exports soldiers for combat on primitive or more advanced worlds (the military units are referred to as "Archs" and "Mechs" respectively). In Alan Nourse's Star Surgeon, each species has a specialty, and Earth's is medicine; this sets up a story in which the hero is a nonterrestrial doctor who faces prejudice in his attempt to succeed in the Terran-monopolized interstellar medical system.

Live-Action TV

 * Babylon 5 is a Service station, providing a interstellar forum, among other things. The various homeworlds tend to serve as Capitals of the major powers. There is a brief mention of a Disneyplanet. Z'ha'dum is considered forbidden.
 * Babylon 5 itself is only the size of a fairly small city though and it is not uncommon for a whole city to be dominated by a single product; trade and politics are both common products historically. The homeworlds are not implied to serve as just the capitals and Minbar clearly has other products. Lennier's conversation with Zach at the beginning of Atonement makes it clear that Minbar produces high quality textiles. Thus it is reasonably justified in B5.
 * Battlestar Galactica: The 2003 version had the Twelve Colonies of Kobol set up as such. Aerilon was the "bread basket" of the colonies. Caprica was the Capital and Cultural Center. Gemenon is a Holy Center. Libran is known for its lawyers. Picon has Strategic value (the Fleet HQ was located here), and a Cultural Center since it was used as a substitute for Caprica in entertainment. Scorpia had Shipyards, and Tauron was another Farm center.
 * Following the Fall of the Colonies, the Rag-Tag Fleet's economy is set up like this. Justified, in that only certain surviving ships were only equipped for certain functions.
 * Doctor Who has featured many such examples. "Silence in the Library" takes place on a library planet. Satellite 5 is a Service station providing news . Billions of Years in the Future, Earth is a Cultural and Historical Center.
 * Stargate SG-1: Most worlds are valued as Mines for rare materials, although Libraries, Big Dumb Objects, Farm worlds, Forbidden worlds, and Superweapons make appearances.
 * Star Trek: Earth serves as the Capital, though oddly enough unprotected in many movies. It, along with Mars, also has Shipyards. Risa is a Pleasure Planet, Rura Pente as a penal world, and various Unobtainium mines, Big Dumb Objects, Forbidden locations, and Exotic places.
 * Star Trek: The Next Generation shows us the trope in action. In the episode Symbiosis, One of the two planets of the week produces nothing but a narcotic which the other planet believes is a cure to a virulent plague (whose symptoms just happen to look exactly like withdrawal).
 * An early episode of Farscape deconstructs this trope: Sykar was forcibly remade into a farm world by the Peacekeepers; most native plantlife was almost completely destroyed to make way for vast fields of Tannot root, and every single inhabitant of the planet were reduced to farm-labourers, planting, tending and harvesting the crops. Thanks to the high demand for Tannot root, the farms themselves are steadily being worn out through overharvesting and reduced to barren wastes; the one seen in the episode is said to be the last fertile region of the planet. For good measure, the only thing stopping the Sykarans from noticing any of this is the fact that their food is made entirely of mind-control drugs, and they all believe that every day is the last day before a weekend.

Tabletop Games

 * Fading Suns: Uses the trope, with many different examples.
 * Warhammer 40000: Many worlds are known for what it produces to the Imperium's war machine: Agri worlds produce food, Mining colonies inorganic raw resources, Death worlds provide military forces, usually specialists, and sometimes exotic biological products. Feral and Feudal worlds are primitive versions of one of the above (e.g. Unloth is a Feral world, but it was given orbital infrastructure, so there was a whole cruiser built at such a place after the locals "sacrificed" smelted metals at the "sky temples" long enough) or a generalist mix. Forge worlds specialize on high technology and heavy industry, rare Industrial Worlds on mining and heavy industry. And so on. Hive Worlds and Civilised Worlds are general classes, but they may specialize too - e.g. Civilised worlds include variants such as Mining world (once infrastructure and population outgrows a colony level and it becomes less dependent on everything) or Paradise World if left mostly pristine (which does not always mean it won't produce anything but services, and occasionally recruits) - or at least famous for particular low-tech products or military units. Some planets produce exotic resources, but there are many of those, too.
 * Special variants include Penal World import the undesirables and export spare manpower and products of hard labour, Shrine Worlds serve as pilgrimage destinations and export trained priesthood, Fortress Worlds muster disciplined troops, but often keep most for the local use if they are in currently or permanently strategically important locations, like Cadia. Holy Terra is both the Capital of the Imperium's power structures and institutions.
 * Sometimes played straight, often averted by Traveller, most planets have a variety of trade goods available, usually randomly rolled but influenced by planet type.

Video Games

 * Wing Commander: Privateer put the player in the shoes of a freelance ship owner during a peaceful period of the Terran Confederacy's reign. While the most obvious route to take was killing anything that shot at you, it was entirely possible to make a living solely from trading between the planets, each of which had a specialty. Due to this, each planet would produce certain goods cheaper than elsewhere and purchase some goods for more than other planets.
 * Buy food from a farm planet, sell it to a mining asteroid; buy minerals from the asteroid, sell it to the factory planet; buy machinery from the factory, sell it to the pleasure world; buy titty magazines from the pleasure world, sell it to the farm planet. Ah, the circle of life...
 * EVE Online usually subverts this, there are usually a wide variety of goods available at a given market.
 * while this is true for the stations in the orbits, with the planetary interactions and the general Single Biome Planet, many players play this straight: get a temperate planet as factory world to make tier 3 or 4 products, while the other planet types often make mine worlds to get the supply for the temperate one.
 * Also about the moons, as you can only have only one POS (Player Owned Station) in their orbit: some are deathstars loaded with weapons, others have factories or science facilites, and others are just there to mine the moon if it holds valuable resources.
 * Mostly averted in the X-Universe games, but some sectors specialize in only a few types of goods. Asteroid Belt in Terran Conflict mostly produces different types of minerals from the asteroid mines, for example.
 * Partial example in the Escape Velocity series, where bulk commodities can be purchased at most worlds. Usually, among the generics (food, metals, equipment, luxuries, medical supplies) one or two will be cheaply available and one or two will be more expensive. However, in Nova, many worlds have a "special" commodity that is generally only traded at two or three worlds (some supplying it, others demanding it), which are either quite valuable or just interesting flavor.

Western Animation

 * Invader Zim: The Irken Empire from Invader Zim has conquered numerous alien planets to give them a convenient specialization. Some examples: Blorch, the new parking structure planet; Callnowia, the mail order planet, along with Conveyor Belt Planet for shipping; Conventia, the convention hall planet; Foodcourtia, the food court planet; etc. They have so many they don't even really have a plan for new planets until they conquer them and wipe out the lifeforms present, then they just decide on a whim what kind of new planet might be handy or fun.