Beam me Up, Scotty!

So far the locations of the captains found are in these missions.

Mission 3 left of your starting point.

Mission 4 on the ledge separating the bottom and middle lanes to the right of your starting bases turret.

Mission 5 it is just below the base by the bottom turret on a grey ledge

Mission 6 to the right of the diplomats crashed ship in the corner.

Mission 7 on the top of north (second) base just above the left turret on the ledge.

Don't Bother looking in these missions

Mission 1, Mission 2

Spec ops missions - Into Darkness, Uninvited

Beam me Up, Scotty! is an achievement in Iron Marines.