Asteroid mines yield ("beam") extra manufacturing points to the nearest same civ planet. Planet can be changed by selecting the mine then right-clicking on the new target planet. % of total possible points recieved from a particular mine is diminished by the distance to the target planet. Later levels of Space Mining technology increase the points produced by upgraded mines, but the mining ship DOES need to revisit to upgrade the mines. Manufacturing points from asteroid mines are "potential" production just like factories, that is, they still have to be funded with money.
drrider
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