Astronauts: Toughest Job in the Universe

Astronaut Chris Hadfield, former NASA medical researcher Dr. Kevin Fong and psychologist Dr. Iya Whiteley put 12 exceptional candidates through a series of grueling physical and psychological tests to find out who has what it takes to be an astronaut. Using the demanding criteria of space agencies, they must hover a helicopter, take their own blood and be tested for claustrophobia, physical fitness and mental agility. Those who fail to make the grade can be asked to leave at any time.

The remaining astronaut candidates are put through more demanding tests by astronaut Chris Hadfield and his expert panel. Some are pushed to their limits in a simulated emergency splashdown, where they have to escape from an underwater capsule. At the UK's biggest space-tech firm, they must successfully operate a ground-breaking robot, the Mars Rover. A social event gives Chris and the panel a further chance to scrutinise their character. Not all candidates make it through this phase of selection.

Old fears surface when the remaining astronaut candidates face a series of space agency swim tests. Their teamwork and mental agility is scrutinised in an underwater test, assembling a large cube. They learn basic Russian before heading off to the German Space Centre. In a simulation used to train astronauts, they attempt to dock the Soyuz space capsule with the International Space Station. They are subjected to a spin in the facility's rotating chair and more candidates are sent home.

This week, the competition becomes more intense as the remaining astronaut candidates head off to a secret facility in Sweden. They are deliberately deprived of oxygen to see if they can recognise the signs of hypoxia, critical for an astronaut on a spacewalk. Their ability to withstand the strong g-forces of space travel is tested in a human centrifuge. Their communication skills are put to the test as well as their ability to impress Chris and the panel with their specialist space knowledge.

The astronaut candidates fight for their place in the final. Their leadership skills are assessed in a survival test and a 30 metre abseil down a sheer cliff face exposes weaknesses in the group. Chris Hadfield and the panel are joined by two guest experts for probing interviews to grill the candidates on whether they have the right stuff. Those who make it through this stage head off to the Kennedy Space Centre in Florida and carry out a spacewalk dive in an underwater marine lab.

The finalists head to the Shuttle Landing Facility on Florida's Space Coast as Chris Hadfield probes whether they have considered the risks of the job. They experience weightlessness for the first time as their motor skills are tested at 30,000 feet. In the Florida Keys, they dive down to the Aquarius underwater facility, used by NASA for training astronauts.