Hyperspace hub

The hyperspace hubs are a system of interstellar, intergalactic, and inter-universal transportation devices. They permit zero-distance travel between widely separated locations through their gates.

Structure
All known hubs consist of two gates: a small interior gate and a large exterior gate. Gates are circular and, with notable exceptions, one-sided. Interior gates are all 203.2 meters in diameter; exterior gates are 42.87 kilometers in diameter. The hub structure itself is always embedded in a moon. It is theorized that their may be hubs contained in asteroids or dwarf planets, but none have been found. All known hubs have extensive habitable structures surrounding the interior gates, along with infrastructure for controlling and operating the hub and airlocks for docking. Some have a tertiary gate 101.6 meters across that connects solely to a matching gate on the terrestrial planet the hub orbits. In inhabited systems, hub interiors have an atmosphere nearly identical to the nearest inhabited planet, or did prior to the Alliance hub equalization initiative. With only one known exception - the Solar System - there is at most one hub per star system.

Origin
The origin of the hubs is unknown. Though used by the Phfohr, they are not Phfohr technology and appear to have been appropriated by them just as by the Alliance and Federation. An unknown species of aliens, dubbed "the Progenitors" by some, is believed to have constructed the hubs eons ago for unknown reasons. It is suspected that the same aliens were responsible for the metahuman diaspora, scattering metahumanity to its many homeworlds. Other than the hubs, there is no evidence of the existence of these Progenitors, so nothing is known of them other than that someone made the hubs.

Function
Despite learning to operate and manipulate the hubs, neither metahumanity nor the Federation have learned much, if anything, about how they work. They are believed to create wormholes between their endpoints, but how this is done and how it is targeted are entirely unknown. Attempts to reverse engineer the defunct Dysnomia gate have failed entirely. No means have been discovered, aside from the gates, to exceed the Alcubierre limit of 10c.