A Vulcan robot ship was a type of unmanned vessel used by the Vulcan Offworld Service in the mid 21st century. In late 2045 or early 2046, a Vulcan robot ship prospecting for antimatter in the interstellar void was discovered by Sorahl, who was traveling from Earth back to Vulcan on a commandeered DY-100 sub-light vessel. Sorahl was able to override and adapt the robot ship in order to get himself and his commander, T'Lera, back to Vulcan within a year. (TOS novel: Strangers from the Sky)