Place a resource required for the "space race" in the "trade civ" locations. One resource can do. Set up the conditions so that a civ must settle near the resource - no way to connect the resource to the trade network. Then the "part(s)" must be built in that location. A single resource can be the sole requirement for multiple parts since buildability can be triggered by tech advances. A civ will have to find the resource, settle, defend the location & take a long time to build a valuable key to victory. A lot like locating trading partners, creating trading centers near the frontiers, spending decades cultivating exclusive trade networks, etc.