A target drone was a type of probe which could be launched from a starship.
In 2372, Doctor Lenara Kahn utilized a target drone in her attempts to create a stable artificial wormhole. Conducting her experiments aboard the USS Defiant, Doctor Kahn's procedure involved launching the drone, which would then send out a magneton pulse to react with a subspace tensor matrix to create an opening in the spacetime continuum. The magneton pulse created a feedback loop which destroyed the drone, but not before successfully creating a short-lived wormhole. (DS9: "Rejoined")