It is not a constructor function.  Finally, something you don't need yet another constructor for.     (Actually I love constructors and watching clouds of them roam my empire improving things.)  If you select the asteroids, it will let you "Buy" an asteroid mining station on that patch of asteroids.  It costs 500 credits and gets you 1 production per turn minus whatever the distance decay is.  I don't know that one yet.

Edit: ninja'ed

My opinion is that while this game totally revolves around Raw Production, it seems a bit costly to spend 500 credits to build a mine returning only 1 RP. Yes, I know that RP can end up getting multiplied with bonuses a couple of times, but this still seems costly. I'd like to see the cost/mine lowered somewhat. Opinions please.

EDIT: As far a costs to build mines, I have to ask what is the baseline cost for the Merc that gives +5 RP to a planet?

thx .. neilkaz ..

700 sounds low, maybe it is 900. Anyhow, I think that cost/mine should be only 250 credits or at most 300.

I agree they are expensive.  And there aren't that many percentage bonuses for production, either.  So, it is hard to make back your original investment in credits with return in production.  I think the price should get discounted as you get mining techs.