I am imagining the Astrogation Temples, where you go to have your journey mapped. The mapping takes place in empty rooms with vaulted ceilings, where stone moon scultpures are put into motion on hard light holograms.
Why is it a temple? Because all journeys have religious significance. The navigators are trained in anthropological religious studies, helping humans keep in touch with their humanity while traversing the void. They might offer a parable or an argument or sit you down for a meal with a nearby family or offer guided meditation with their coordinates.
Astrogation computers are available but only used in an emergency. Computers have a rough time around Leviathan. The gas giant’s magnetic radiation wreaks havoc with any complicated computer and A.I. research is strictly forbidden because of the fell effects Leviathan’s pull has on synthetic entities of any kind.
The Ducal Moons are held by the 4 Major Houses: Job, Triton, Rangomai and Mizuchi. In the centuries since their settling, the moons have changed hands a number of times with houses Major and Minor rising and falling on a political tide.
Baikonur was the first moon settled and is held in trust by the Unions and Temple. The Major Houses take turns guarding it, changing every 4 cycles. Baikonur, because of its special place in the orbits, was named for a spaceport on Olde Earth, rather than a nautical port.
Morgan did his public twitter chargen and he rolled up a Traveller Noble and prodded at me to think about knife fights in space.
And we did.
Dozens of moons surrounding a gas giant with a satanic storm eye moving to and fro. The gas giant is called Leviathan with dozens of moons and enough asteroids in its rings that new moons are still discovered.
There are 4 major houses: Job, Triton, Rangomai and Mizuchi charged with defending the ducal moons with the finest atmospheres with a dozen more houses minor picking up the scraps. Those with noble titles and their knights can wield fighting knives. They are trained with rifle and pistol but the ammunition is controlled by the Unions – laborers, crafters, and engineers who make sure those with title don’t drag everyone into frivolous wars.
War Mechs and Battlecruisers are only unlocked if there is an outside threat.
Alien artifacts on the solid planets closer to the system’s sun.
A science-station observatory at the edge of the system; this is where aging nobles who are found to be too warlike are exiled to.