A Vulcan survey ship was a type of spacefaring vessel utilized by the Vulcan High Command for conducting survey missions during the mid-20th century. Among other duties they performed were statistical scans from high orbit.
A well-documented incident found at the Vulcan Science Directorate and Space Council, but without common Human knowledge, involved a Vulcan survey ship in 1957. Sent to investigate the launch of Earth's first artificial satellite, Sputnik, the Vulcan craft's impulse manifold began to malfunction during the third week of intelligence gathering, forcing the Vulcan crew to attempt an emergency landing. The vessel crash landed just outside Carbon Creek, Pennsylvania. The captain perished in the crash, leaving command to T'Mir. In addition to T'Mir, there were two other survivors of the crash: Stron and Mestral.
Later, Mestral asked to be allowed to remain on Earth. Believing it would satiate his curiosity, T'Mir suggested that she could arrange for him to be on the next survey ship that studied Earth. Mestral was displeased by the prospect, believing it would not happen for another twenty years and would be limited to running statistical scans from a high orbit. (ENT: "Carbon Creek")