My Python has two fixed charge launchers - with practice it is possible to lodge charges in fissures that are almost out of sight around the asteroid: it takes a bit of leading the target but it can be done (I find the offset launchers can help to lead my target correctly, and it is nice to be able to alternate launch angles). I'd suggest practicing on non-opal core asteroids to start with (i.e. don't go for max profit immediately). I find night vision helpful. I'd also suggest, if you can't see any blue fissure icons on your side, sidestrafe in the direction opposite the rotation to bring other fissures into view. (And if the blue icon appears to be moving opposite to the rotation, it is actually on the far side.)