You must build a RM ship/base/sat on each asteroid field (an unfortunate name, as it refers to only the asteroids in a single sector). You can only use one ship or base, or a satellite, to mine each sectore. You can stick as many RM comps on that ship or base as you want. With satellites, you can have 3 in the sector, but they must all be mining different types of resources.
And remember the panels use fuel... . (nothing like having ships run out of fuel out there)
__________________ ALLIANCE, n. In international politics, the union of two thieves who have their hands so deeply inserted in each other's pocket that they cannot separately plunder a third. (Ambrose Bierce)
But they still keep working after your supplies run out, so you only have to worry about it when the mining is no longer profitable and you need to send the ship somewhere else!
(And of course you don't need to worry about it at all with bases and satellites!)
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The Ed draws near! What dost thou deaux?