The class-5 probe or level-5 probe was a medium-range probe carried aboard Federation starships and used as a reconnaissance probe and for planetary analysis. It was equipped with visual sensors, as well as sensors that could detect the chemical contents of an atmosphere and geological sensors. It maintained orbit with impulse thrusters. The probe had an operational life span of over two hundred years, by which time its thrusters would permanently degrade. (VOY: "Blink of an Eye")