A transwarp hub is a form of warp technology which allows for faster than light travel at speeds exceeding the theoretical limits of standard Federation speeds as marked by the Warp scale whose maximum speed is Warp 10.
The best examples of transwarp hubs were constructed and utilized by the Borg. By the late 2370s, the Borg transwarp network consisted of six hubs located throughout the galaxy including at least one near the Delta Quadrant/Beta Quadrant border, hidden in a nebula in Grid 986.
The successful use of these hubs requires the addition of numerous interspatial manifolds to keep the transwarp conduits open. Additionally an even larger structure would be needed to keep the transwarp apertures open long enough to allow a ship to go through. This is a long and complex construction task and took some years to accomplish for the Borg, even with their vast resources.
In 2378, the USS Voyager encountered the hub in Grid 986 after it detected elevated neutrino and graviton levels coming from it. At first the readings were taken to indicate that there were thousands of stable wormholes present in the hub but brief exploration of the nebula revealed the true nature of the readings. The hub was defended by the Queen and at least 47 Borg cubes. Additionally, the shielding for the aperture structure was controlled by the Queen directly from Unimatrix One and could only be destroyed from there. Accordingly, Voyager initially chose to retreat rather than face the armada of cubes that protected the structure. However, the vessel eventually returned to the hub, destroying an interspatial manifold with modified transphasic torpedos. The vessel destroyed the manifold only after passing through aperture 823 and returning to within one light-year of Earth, ending their seven-year exile in deep space. A simultaneous attack at Unimatrix One by Admiral Kathryn Janeway ensured that the whole Borg tranwarp network collapsed on itself, along with an unknown number of Borg drones and vessels.
It is possible that portions of the actual hub network remain intact, but without the components to allow it to be used for transwarp transport.
- In an alternate timeline, Voyager did not utilise the transwarp hub. It took the ship an extra 17 years to get home, costing them another 22 lives within the crew, including Seven of Nine's. The decision not to use the hub to get home caused Kathryn Janeway great pain, until she eventually completed a plan to change history in 2404. She went back in time to 2378 to get the crew to return home early. (VOY: "Endgame").