I've researched through Sensors Mark IV. According to the tech descriptions, I should be able to build the following starbase modules: Perimeter Scanners, Sector Scanners, Sector Surveilance Scanners, and Ultimate Surveilance Scanners.
But none of these ever show up as choices when I move a constructor to a starbase. How do you build these modules? I've checked on mining and economic starbases - are they only available for some other type?
