Once a base has at least one spaceport built, it can start a trade route with another base.
The initial cost of the trade route is determined by the distance between the two bases; for example, a trade route from a base located in A00:49:10 to a base located in A00:59:10 will cost 10 credits, since they are 10 lightyears apart. If a trade route is set between 2 different players, both players pay half the trade route cost.
A trade route will provide income to a bases, equivalent to:
Trade Income = Sqrt(Lowest base's income) x [ 1 + Sqrt(Distance)/75 + Sqrt(Players)/10 ]
Where Players is the number of players involved in your trade network.
A base can have one trade route for each 5 levels of spaceports - 1 route at level 1, another at level 5, another at level 10, etc.
Trade routes can be plundered by other players, which terminates the trade route and gives a profit to the plunderer, equal to the trade route's cost.
Closing trade routes
When a trade route is canceled, each trading partner receives a 50% refund. The route then enters a "Closing" status for 12 hours if under 1000 distance, or 24 hours if longer. Pillaging a base yields 50% of the cost of any closing trade routes, which are then terminated.