I got the impression that the mine field beyond Star One had been in place for some time, possibly even centuries.
It's funny how they give that impression and yet, according to Pressure Point and Gambit, Star One has only been there 30 years, and the crew rotated fairly regularly (I say rotated, the existing crew are likely killed to maintain the secret). Dureena must have arrived fairly recently as that bloke was fond of her.
My point - how was the minefield controlled before Star One? From Control on Earth?