First broadcast: on BBC Two EnglandLatest broadcast: on BBC Two Northern Ireland
Chris Hadfield, Dr Kevin Fong and Dr Iya Whiteley put 12 candidates through a series of physical and psychological tests to find out who has what it takes to be an astronaut. Show more
First broadcast: on BBC Two HDLatest broadcast: on BBC Two Wales
Old fears surface when the remaining candidates face some space agency swim tests. Their teamwork and mental agility are scrutinised in an underwater test, assembling a large cube. Show more
First broadcast: on BBC Two HDLatest broadcast: on BBC Two Wales
The competition becomes more intense as the remaining candidates are deprived of oxygen to see if they can recognise the signs of hypoxia, critical for an astronaut on a spacewalk. Show more
First broadcast: on BBC Two HDLatest broadcast: on BBC Two Northern Ireland
The astronaut candidates fight for their place in the final. Their leadership skills are assessed in a survival test and they head off to the Kennedy Space Centre in Florida. Show more
First broadcast: on BBC Two HDLatest broadcast: on BBC Two Wales HD
The finalists head to the Shuttle Landing Facility on Florida's Space Coast for a tough test in weightlessness, and back in London the winner is decided. Show more
First broadcast: on BBC Two HDLatest broadcast: on BBC Two Northern Ireland HD
The remaining astronaut candidates are put through more demanding tests. They have to escape from an underwater capsule and operate a groundbreaking robot - the Mars Rover. Show more