One strategy for Danger Zone level 18 is to send the Black bird along the southern hemisphere of the planet, detonating after it reaches the structures. Send Terence along a similar trajectory, only further from the planet. The goal is to pass through the bubbled pig and into the top structure. With a little luck, either Terence, the asteroid, or debris will reach the TNT atop the planet, clearing the level. The score in the video below is 141,510.