Astronaut
Astronaut was a term used to describe early Earth space travellers. Various individuals that were part of the British and American space programmes were called "astronauts". (DW: The Ambassadors of Death) Wilfred Mott claimed to have always wanted to be an astronaut, when he noted he had accidentally become one after being transported to the Vinvocci spaceship. (DW: The End of Time)
The "Impossible Astronaut"
An Apollo 11 space suit was stolen by the Silence and used as mobile life support for Melody Pond in 1969. Footage of astronaut Neil Armstrong's first step on the Moon was later used to defeat the Silence. (DW: The Impossible Astronaut, Day of the Moon)
In her adulthood, Melody Pond, now known as River Song, was taken by Madame Kovarian and the Silence to kill the Eleventh Doctor. She was submerged in Lake Silencio, Utah, to wait for the Doctor where she would kill him at 5:02pm on 22nd April, 2011. Kovarian explained that "an impossible astronaut will rise from the deep and strike the Time Lord dead". (DW: Closing Time) However, the Doctor managed to cheat death as he had the Teselecta in his place. (DW: The Wedding of River Song)
