Imperial probe droids, or probots, are used extensively by Lord Vader's squadron in the search for the mian Rebel base after the Battle of Yavin. Vader ordered thousands of probots to be sent out to enexplored or uninhabited systems in hope that one might uncover the Rebels; inded, a probot discovered the Alliance base on Hoth.
    The probots Vader used were Arakyd Viper Units, one of the top military probe droids manufactured in the Empire. These probots have two main componenets. The first is and exterior hyperdrive pod, which transports the probot inside across thousandsof light-years to its destination. These pods are one-use-only, meaning that each probot is sent on a one-way trip. After deployment, probots areleft behind to continue observation.
    Upon arriving at the destination world, the pod streaks in to the planet's surface, applying emergency braking thrusters. Observers often mistake arriving pods for meteorites. After impact, the pod opens to release the probe droid.
    Probots are very intellegent droids. Equipped with repulsorlift and thruster units, they can move across planetary surfaces at about forty kilometers per hour. They are cunning and incessantly curious: if there is anything to be found on a world, a probot will find it. They are armed with a blaster, althought they are programmed to avoid conflict and to self-destruct if discovered by enemies.
    Probots have extremely sensitive sensor arrays that are used to detect signs of habitation, with acoustic, electromagnetic, motive, seismic, and olfactory sensors. Optical cameras, zoom imagers, infared scopes, magnetic imagers, radar and sonar transceiver, and radiation meters all combine to give the probot a detailed view of the world around it. Four manipulator arms and a high-torque grasping arm allow the probot to take samples from the planet, while protected and retractable ultrasensitive sensor probes extrude from the arms for detailed close scans.
    The probot on Hoth made detailed observations of the Rebel base, reporting the location of shield generators, artillery emplacements, and troop deployments, thus giving the Empire excellent intelligence before the assualt. While Han Solo and Chewbacca did destroy the probot, the droid had already completed its mission of leading the Empire to the Rebels.