Famous MPA megastructure consisting of multiple Dyson shells, each following the form of one of the Platonic solids.
Image from Anders Sandberg
Stylized not-to-scale illustration of Kepleria's shape and layout. The actual megastructure's edges are much longer relative to their width and to the central star.

Kepleria - Data Panel

SystemName: Kepleria

Primary: Johannes (HD 152219)

Constellation: Scorpius

Right ascension: 16h54m08.51s

Declination: -41°49'36

Stellar Type: Originally A type, now F type after having undergone starlifting to obtain 0.68 solar masses of material for habitats and wormholes.

Companion: None

Region: Mutual Progress Association

Distance from Sol: 531 ly

Planets: Originally 10, all disassembled

Megastructure Type: 5 partial Dyson swarms
Important Local Artificial IntelligencesAI overseer: Sacred Geometry, S4

AI's ethos: Gardener; social guidance; symmetry and order
PolityName: Kepleria

Symbol: The 5 Platonic solids nested inside one another.

Affiliation: Mutual Progress Association

Founded/Colonized: Construction began 6996 and was completed in 9998. Colonization of habitats is ongoing; many are still completely wild and unpopulated by sophonts.

Tech Level: Varies depending on location and society.
Territory and PopulationModosophonts: 13.82 quadrillion
Nearbaselines: 8%
Vecs: 24%
Provolves: 15%
Neogens: 21%
Cyborgs: 9%
Virtuals: 15%
Xenosophonts: 3%
Other: 5%

S1: 41,500
S2: 36
S3: 5

Territories: Johannes system
Government and AdministrationGovernment Type: Varies depending on location and society, but generally with transapient memetic guidance.

Administrative Divisions: Varies depending on location, society, and overseeing transapient.

Constitution: Based on Beta Arae protocols.

Legal System: Based on Beta Arae protocols.
Economics and InfrastructureMajor Industries: Tourism, environment design, gengineering, scientific study

Local Travel: Space transports connect each vertex of each Prime Shape on the megastructure, with an array of routes to destinations both near and far. Internal transport systems run between and within the habitats making up each Prime Shape.

Angelnetting: Complete in most populated areas.
TravelStargates: Kepleria is located at a relay node of the Wormhole Nexus, and so has 100 wormholes locally available for travel.

Beamrider routes: 12 beamlines

Lightways: 12

Hazard Rating: 0 in heavily populated areas, up to 2 in sparsely populated places, up to 5.1 in wild areas.

Freedom of Movement: No restrictions in populated areas, but permits may be required to enter some wild regions under protection from outside contamination.

Throughout the more than 7,000-year history of the Mutual Progress Association, a remarkable amount of mega-scale engineering has taken place, totaling more than all other Terragen civilizations throughout history. This has propelled the MPA to almost all of the top entries on lists of Wonders of the Modern Galaxy. One such entry, one of the most astonishing and famous feats of macro-engineering anywhere, is the megastructure Kepleria, consisting of an open framework, multi-layer, quasi-rigid Dyson structure around the star Johannes (YTS 6465-7800-313), deep in the heart of MPA territory.

The five layers of Kepleria are a reconstruction of Johannes Kepler's 4th century BT concept that the six known planets at the time (Mercury, Venus, Earth, Mars, Jupiter, and Saturn) had orbits that could be perfectly predicted if one nested the five Platonic Solids (polyhedrons whose faces are identical regular polygons) inside each other. Unfortunately for Kepler, his ideas did not stand the test of observation and science, and even in the Information Age one would read of his fascination in history books, not science books. Although history was not kind to Kepler's grand idea, today there is no doubt that he would be very pleased to see it incorporated into an actual structure. It is perhaps an interesting historical footnote that Kepler had a plan to build a small scale model illustrating his concept, but he intended to use it as a beverage dispenser.


The idea for Kepleria was initially proposed by Ptah, The Constructor of Worlds, one of the primary MPA archailects. Ptah took delight in reshaping matter and especially creating new environments and worlds for Eir citizens to live in. While the MPA was founded for reasons other than letting Em play, E was one of the triumvirate of archailect gods (together with Binah and Brunel) that helped form the Association. In fact, Ptah was the most extroverted of the three gods and for that reason was most influential in the development of the composite entity known as the Great Architect or the Creator of Structures, the ruling spirit of the MPA.

The practical construction of Kepleria became a pet project among the transapients working for Ptah. They felt it fit perfectly into the materialist worldview promulgated by the Association, which believes the very existence of the universe itself is defined by the structure of matter within it and views the creation of physical structures in space as a devotional duty in its own right.

The first shell, Octahedron (or Octa for short), was begun in 6996 and completed in 7231 at a distance of about 0.234 AU from Johannes. The second shell, Icosahedron (or Icosa), was begun in 7217 and completed in 7999 at a distance of 0.702 AU. The third shell, Dodecahedron (Dodeca), was built between 8101 and 8890 at 2.106 AU.

After Dodeca's completion, further progress was delayed for over 270 years. The root of the problem was a difference in viewpoint as to how to proceed with development of the system. The inhabitants of Icosa wanted to completely enclose the star with solar collectors to provide enough energy to run ever more and larger virchworlds; however, this would have cut off power to Dodeca. Meanwhile, many inhabitants of Dodeca, who were descended from a recent wave of bio-materialist immigrants from the Zoeific Biopolity, were engaged in creating extensive vacuum adapted free-space ecosystems on and around their layer, which would have trouble surviving in anything like their original forms if Icosa went through with its plan. Additionally, the Dodecan ecosystems, if allowed to develop as fully as first planned, would cut off energy from the two further layers yet to be constructed. Faced with such a host of apparently conflicting goals, many of the inhabitants of both Icosa and Dodeca and even their regional transapient overseers (who may have simply been humoring them or possibly had their own internal disputes) began to play political games with each other, with everything from the Octa population to construction swarms being used as pawns. Much effort was also put into memetic subversion by both sides.

For most of this period, Ptah attempted to follow Eir usual course of letting things play out according to the will of the sophonts under Em. However, it ultimately became apparent that E would have to intervene in order to get the project finished in a timely manner. As a result of Eir memetic influence (and gift-tech that allowed the modosophont creation of conversion-based plasma processor systems), Icosa was able to continue its development of new virchworlds without the need for solar power and therefore lost interest in intercepting additional energy from Johannes. Dodeca in turn was convinced to temporarily limit its development of vacuum-based lifeforms to those adapted to live on the outer surfaces of the Dodecan layer on the promise that they would have access to a full 1% of the meta-surface of all of Kepleria's other layers, both existing and yet to be built. The few existing free-space ecosystems would be preserved and then moved to the Cube once it was finished.

When the project resumed in 9168, the next layer, Tetrahedron (Tetra), was completed in record time, in 9439. This is especially remarkable considering that construction took place at a distance of 6.318 AU. The dual factors of improved technology and multiple wormholes for transportation of matter contributed to this. The largest and final layer, the Cube, was begun in 9550 and finished in 9998 at a distance of 18.954 AU. This was the fastest rate of building during the entire project.

Kepleria suffered damage during the Oracle War, but the outer layers were the worst affected; some Prime Shapes became detached and began to fall towards the central star, and were rescued and repaired with some difficulty. A worse problem was the free-falling debris caused by the damage, all of which had to be collected before it impacted the inner structures.

Kepleria -Tetra
Image from Steve Bowers
The Prime habitats of Tetra are arranged into long strings, ten to each edge; when stacked, these tetrahedra form a spiral-like structure known as a tetrahelix.

Each Dyson shape is made up of a great many Prime Shapes, themselves made up of various habitats arranged in the same layout as the larger Dyson shape they are a part of. Thus, the Cube is made up of Prime Cubes, the Tetrahedron is made up of Prime Tetrahedra, and so on. The Prime Cube will be considered as an example.

The central structure of a Prime Cube consists of 12 cylindrical and 8 spherical habitats, arranged as the 12 edges and 8 vertices of a cube. At the smallest scale, each cylindrical habitat is 10 km long and 1 km in diameter. The cylinders are divided into 5 levels, representing the fact that there are 5 Platonic solids. The innermost level is 500 m across, and each level outside this is 50 m from ceiling to floor. Since each level goes all the way around the cylinder, this is an increase of 100 m in total diameter with each level. Towers, gengineered trees, or buckyfiber cables may connect the levels.

Each vertex is twice the diameter of the cylinders, which makes them 2 km across at this scale. While the cylinders are rotated for artificial gravity, the vertices exist in freefall. Within each vertex are 13 smaller spheres of equal size. The central sphere is computronium, supporting either a managing transapient or a set of virchworlds. The other 12 spheres are arranged in a cuboctahedral arrangement around the central sphere. Each sphere may be enclosed and support a different environment, or be an open framework, perhaps surrounded by gengineered freefall plants and related ecosystems. The surrounding space in the vertex may be filled with liquid, gases, or vacuum. Artificial lighting illuminates the interiors.

This 10 km by 10 km cube of habitats is set within the center of another, larger cube of habitats, which in turn is set inside a larger cube and so on up to a total of five layers of habitats. Each smaller cube is connected to the next layer up via dynamic compression members and transport routes between the vertices of the different levels. Each level of the Prime Cube is bigger than the last by a factor of 10. The next level, for example, is 100 km by 100 km, made of cylinders 100 km long and 10 km in diameter, with internal levels separated by 500 m, and vertices 20 km across. This, in turn, is set within another level 1,000 km by 1,000 km, which is within another level measuring 10,000 km by 10,000 km, which itself is within the largest level, which is 100,000 km on a side.

The cylinder habitats of the outermost level of a Prime Cube are 100,000 km long and 10,000 km in diameter, with each of the 5 levels separated by 500 km, and the innermost portion being 5,000 km across. The inner volume is typically lit by plasma processors and may contain freefall atmospheric masses, smaller free flying habitats, Dyson trees, asteroids or some combination of all of these within its open interior. A few cylinders of this size are reinforced with magmatter so as to stay in one piece while being rotated for 1g of artificial gravity, but most rotate more slowly for low gravity, generally about 0.15g. Some even have no artificial gravity at all.

The largest vertices are 20,000 km across and use circulating mass streams to hold their outer shells rigid. Their interior computronium nodes are moon brain size and sometimes incorporate plasma processors.

A Prime Shape can support a wide variety of ecosystems. The pillars connecting different levels in the cylindrical habitats may support multiple vertical ecologies at different altitudes, while the ceilings support 'upside down' ecosystems. The outer surface of many habitats support vacuum adapted ecosystems and a number of Prime Cubes have vacuum adapted 'jungle' environments stretching across the hundreds of thousands of kilometers of one or more of their faces.

This setup of cylinders, vertices, and levels is followed by the other four Prime Shapes in their respective Dyson layers. Each edge of each Dyson shape is made of 10 parallel rows of the corresponding type of Prime Shape. Going across the edge of the Dyson shape, 5 rows are set at an angle to the other 5 rows, with the corner facing away the central star. This angle is known as the dihedral angle, and is different for each shape - for Cube the angle is 90° , for Tetra the angle is 70.53°, for Octa 109.47°, for Dodeca 116.56° and for Icosa 138.19°.

Given the size of the different shapes, Kepleria contains one of the largest and most diverse collections of living space in the Terragen Bubble. The Cube alone has well over 2.5 billion times the surface area of Earth.

Docking structures, mass stream linkages, magmatter cables, and reactionless drives are attached to the exteriors of many vertices. These hold the entire structure stable and support transport networks connecting different parts of Kepleria together. Internal transport systems also extend throughout each populated habitat and allow a passenger to reach any connected point within an individual Prime Shape in a matter of hours.

Although not the most efficient approach to harvesting a star's energy, the MPA considers these giant structures as much art as anything else. The MPA's motto for Kepleria is "Diversity! Diversity! Diversity!" and this has certainly been fulfilled. With its vast size and variety of ecosystems, gravity levels, societies, clades, and virchworlds, Kepleria has lived up to the MPA's grand vision.

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Development Notes
Text by ProxCenBound, D. David Barbeau, and Steve Bowers
Original by D. David Barbeau and Steve Bowers; revised by ProxCenBound on 12 November 2017
Initially published on 01 March 2001.

Additional Information
Fiction featuring Kepleria

Traveler's Notes: Kepleria