Space stations allow alliances to set up governance over a region of space. An alliance can have multiple space stations.
Creating a space station: You need a level 20 embassy and a level 20 university to build a space station hull. Build the Space Station Hull like any other ship in your Shipyard. Send the Space Station Hull to an uninhabited planet around a star. It will act like a colony ship with the same happiness used and will replace the planet it is sent to. The space station counts as a colony for your empire. Once the Space Station is founded (by the Space Station Hull landing) the station will be under the control of your whole alliance via a vote of Parliament. Space Stations cost happiness to launch. The cost is the same as starting a new colony. Also in calculating costs for your next colony any Space Stations you control count as a colony for that purpose. This happiness cost does not extend to the remainder of your alliance even though they have just as much control over the station as the owner does.
Upgrading modules: Instead of buildings, the space station has modules. The new station will have a level 1 Station Command Center, level 1 Parliament, and level 1 Warehouse built for free. Upgrading or building new modules requires the appropriate plan. A Space Station Lab is required to build module plans for a space station. Plans for the Space Station Modules have long build times, so having multiple Space Station Labs can help to produce plans faster. Only 1 plan can be in the queue at a time.
Restrictions: If your empire owns a Space Station you may not quit your alliance. If the space station is abandoned, the space it occupied will be replaced by an asteroid. Therefore, a space station can only be built at a given position once. Deployment of the space station, like any colony, breaks isolation.