The massive megastructure of Kepleria as seen from 20 AU
Throughout the more than 7000-year history of the Mutual Progress Association, an amazing amount of mega-scale engineering has taken place, totaling more than all other empires throughout history. This has rocketed them to almost all of the top entries on the One-Hundred and One Wonders of the Modern Galaxy list. One of the most astonishing and famous feats of mega-engineering anywhere, and indeed one of the Seven or Sixteen Wonders of the Galaxy in almost every compiled list, is the megastructure Kepleria, consisting of an open framework quasi-rigid Dyson structure around the type A star YTS 6465-7800313, deep in the heart of MPA territory.
The five layers of Dyson structures are a reconstruction of Johannes Kepler's pre-Industrial Age concept that the six known planets at the time (Mercury, Venus, Earth, Mars, Jupiter, and Saturn) had orbits that would be perfectly predicted if one would nestle 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 his idea incorporated into an actual structure. Interestingly enough Kepler had a plan to build one for his own use back in the Sixteenth century c.e., but he intended to use it as a drinks cabinet.
The original plan for Kepleria was initiated by Ptah, Fashioner of Worlds, and one of the primary MPA archailects. Ptah takes delight in creating environments, reshaping matter and especially creating new worlds to live in. While the MPA was founded for other reasons 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 those 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 was a pet project of some of the hyperturing demigods working for Ptah, something they deeply wanted to implement no matter what the cost. In the materialist world-view promulgated by the Association, creating physical structures in space is seen as a devotional duty; the very existence of the universe itself is defined by the structure of matter in within it.
This, the grandest of all megascale engineering projects, was begun in 6996 and the first shell was completed 7231. The first shell was an octahedron at about 0.234 AU distance. The second shell (icosahedron) was begun near the completion of the octahedron in 7151. The Icosahedron was constructed at 0.702 AU and was completed in 7999. The third shell (a dodecahedron) was built between 8101 and 8890 at 2.106 AU. Each shell has a fractal configuration - a honeycombing of triangles in the Octahedron, hexagons in the Icosahedron, etc. Although not the most feasible or easiest approach, the MPA considers these giant structures as much art as anything else. Each of the polyhedrons were and are inhabitable, although the innermost [Octahedron] is chiefly for energy collection (being located only at 1/3 AU). Keeping the shells an open structure solves the problem of light and heat, where the polyhedra are open frameworks surrounding the primary. Each polyhedral edge is a latticework of dynamically supported members; supported within the polyhedra are various sizes of habitat, facing away from the local star, illuminated by reflected sunlight. Local gravity is towards the star, and this decreases rapidly in the outermost shells so much that the outermost habitats rotate for artificial gravity where required. The polyhedra are in turn kept in place using surface structures not unlike drive sails, and are powered by orbiting solar collectors (which form the inscribed spheres of Keeper's models). The polyhedra are linked together not by stiff connectors, but by massdriver streams which keep them in place and allow passengers to ride special shuttles from one polyhedron to the next.
Looking along an edge of the icosahedron section of Kepleria, the closest in.
Completion of the third shell was followed by a severe economic depression and massive rebellions. The higher order MPA hyperturings were forced to intervene on the habitable parts of Dodeca and Icosa. As one could imagine, this was a huge obstacle considering that much of Icosa was covered with jungle and nanotech sealed bunkers. The causes of the rebellion were many, but all related to the over-ambitious scale of the project. The actual trigger seems to have been an internal schism between two of the builders. Octa and Icosahedron had very different views on how to proceed. Octa wanted to fully Dyson-enclose the sun to get enough energy, while Icosahedron was already planting beautiful biospheres on its layer. Both started to play political games with each other, using inhabitants, workers and contractors as political pawns. As a result of this memetic subversion, a large number of local inhabitants/engineers began going on strike, making the economics of the whole project look uncertain and finally causing things to grind to a halt. Heavy-handed responses by local nearbaseline police forces putting down numerous strikes/rebellions with help from foreign mercenaries exacerbated the problem. It became a common sentiment that the managing hyperturings had little regard for the lives of those beings under them, and this caused further unrest (and even some unilateral demopolitical secessions) that lasted for over one and a half centuries.
When the project got back on its feet, in 9168, the next layer, the Tetrahedron, was completed in record time being completed in 9439, which is remarkable considering that it was completed at distance of 6.318 AU. Dual factors of improved technology and multiple wormholes for transportation of matter were attributed to this. The largest and final layer, a giant cube, was begun in 9550 and finished in 9998 at a distance of 18.954 AU! This is an even faster rate of building than the previous layer. The low effective gravity at this distance made the engineering problems somewhat easier, offset by the huge scale.
The cost for such a giant structure was enormous, even for the MPA; the total cost of Kepleria was about twice the total amount of the GDP of the MPA during a three-year period. Together with the other habitable megastructures such as Metropolis Ring City and Oikoumene Dyson these constructs represent two thirds of the total living area of the known galaxy. Many diverse cultures occupy these habitats as clients, most of which are otherwise independent from the Association, but even so the megastructures are a long way from making a clear profit so far.
Kepleria was damaged during the Oracle War, but thanks to the extremely low gravitational attraction in the outer layers, repairs were effected with relative ease.