Maitland's ship

Captain Maitland's ship was a human spaceship that ventured to the Sense Sphere.

History
Thanks to the hostilities of previous humans searching for molybdenum on the Sense Sphere, the Sensorites attacked the minds of the crew. Captain Maitland and Carol were put in a death-like form of stasis while periodically awakened and fed by the Sensorites, while the mineralogist John had his mind opened and had turned insane, but could tell good and evil.

The First Doctor landed on this ship and had the lock to his TARDIS stolen by the Sensorites. After John was cured and the planet's disease, in actuality atropine poison in the aqueducts, was figured out by the Doctor on the Sense Sphere, the ship returned home, having taken the surviving members of the last human expedition — who were responsible for poisoning the Sensorites — into custody. (TV: The Sensorites)

Behind the scenes

 * The closing scene of the story, in which the Doctor and his companions witness on the TARDIS scanner Maitland's ship heading back to Earth, is the first time in the series that a spaceship is seen flying through space.
 * Neither the character of Maitland nor the sets of the spaceship are seen again after "Hidden Danger".