Peel the cantaloupe and remove the seeds. Roughly chop the cantaloupe and cucumber. Place them in a blender with lime juice, salt and sugar. Puree until smooth. Check the flavor; it should be equally sweet and salty. Add a little more sugar or salt if needed.
Add half or all of the jalapeño to the blender. Pulse a few times.
Pour the mixture into popsicle holds. Freeze for one hour, then push popsicle sticks into the center of each cup and return to the freezer until solid. Usually 2-3 hours total.