it should be noted that using 'v' to target turrets often doesn't work well at range, particularly for those of us using joysticks.
that said, my frustration with this part of the mission was more about the task overload. finding the turrets would have been do-able, if i weren't also having to simultaneously defend against bombers, stay alive, and try to pay attention to the book of dialogue scrolling by so fast that i couldn't read it all even if i did nothing else. i was helped a little by knowing that there were beams on the front of the deimos, but that didn't help me with the sides, and IMO the mission shouldn't assume the player knows that.
i'm really terrible with mission names, i don't know which one pawns was. but nothing sticks out in my mind as "learning" the beam locations. i knew the bit about green beam on front from retail.