One cantaloupe, a knife, and five minutes. Your very own (and very tasty) planet-killing superweapon.
Hint 1: Center the “crater” around where the stem was connected so that the darker fibers under the skin point towards the center of it.
Hint 2: Stretch a string around the melon to help guide your equatorial trench.
(Also: you don’t really need that exhaust port. It’s a weakness.)