I'm not sure if it's just my game, but the Lum'en Factory is always starved for resources, desperately so. Not long after starting a new game I managed to get 500000 credits in missions hauling stuff to Lum'en from other places in system within the timespan of a month.
I think the combination of being in a relatively isolated system, along with the huge distances to the nearest planet, combined with the lack of starport (-100% access) completely ruin its economy. By extension its defenses are also ruined, since they lack the supplies to run.