In the last month of the space shuttle programme, Kevin Fong is granted extraordinary access to the astronauts and ground crew as they prepare for their final mission.

In 2011, after more than 30 years of service, America's space shuttle took to the skies for the last time. Its story has been characterised by incredible triumphs, but blighted by devastating tragedies - and the BBC and Horizon have chronicled every step of its career.