Mars Probe 7

Mars Probe 7 was a British spacecraft sent on a mission to Mars in the 1970s. Its crew included Joe Lefee and Frank Michaels. Shortly after landing on the planet, all communications from the crew ceased, even when the ship departed. Concerned, the British Space Programme sent Charles Van Lyden in the Recovery 7 to rendevous with Mars Probe 7. Van Lyden, like Lefee and Michaels, was captured by aliens, who sent three of their ambassadors to Earth in the ship. Shortly after arrival, UNIT was transporting Mars Probe 7 to the space control centre by UNIT when it was stolen by General Carrington's men. The ship was later relocated by the Third Doctor, but when it was opened, it was found to be empty. (DW: The Ambassadors of Death)