On the 15th December, Tim Peake will launch into space to be Britain's first astronaut on board the International Space Station. For the past two years, Tim has been filming a video diary for Horizon showing the risks, pressures and rigorous training required to launch into space. Horizon also talks exclusively to his wife and two children as they prepare to wave him goodbye on his voyage to space. From training in the Soyuz capsule, centrifuges, space station mockups, virtual reality and a huge pool to replicate spacewalks, to dealing with the physical dangers of weightlessness, witnessing his first launch and spending time away from his wife Rebecca and his two sons, this is an intimate portrait and remarkable insight into the world of an astronaut.