Being an astronaut is a job like no other. Of the estimated 100 billion people who have ever lived, only 628 people in human history have left Earth. Tim Peake is one of them. A former test pilot who served in the British Army Air Corps, he was the first British astronaut to ever walk in space, and completed his six-month Principia mission to the International Space Station with the European Space Agency when he landed back on Earth in June 2016. Today on Ways to Change the World, he tells Krishnan Guru-Murthy about his journey to becoming an astronaut, his time on the ISS and the crucial role of Elon Musk and SpaceX in future space missions. Produced by Silvia Maresca.