Put a 1-quart lidded container (or loaf pan) in the freezer to chill.
Make a simple syrup: Combine the sugar and water in a small saucepan over medium heat, stirring until the sugar dissolves, 2–3 minutes. Let cool to room temperature, 15–20 minutes.
Prepare the melon: If not already done, halve the cantaloupe, scoop out seeds, peel, and cut into cubes.
Chill the base, covered, until very cold, 2–3 hours, or set over an ice bath until it reaches fridge-cold (about 40°F/4°C).
Ice-cream-maker method: Churn the cold base according to your machine’s instructions until the consistency of soft-serve, 15–25 minutes.
No-machine method: Pour the cold base into a shallow metal pan and freeze 45 minutes. Whisk vigorously or scrape with a fork to break up ice crystals. Repeat every 30 minutes until fine crystals form and the sorbet is nearly frozen and smooth, 2–3 hours total.
Pack the sorbet into the chilled container, press parchment directly onto the surface, cover, and freeze until firm but scoopable, 2–3 hours.
Before serving, let the sorbet stand at room temperature for 5 minutes for easier scooping. Serve immediately.