The Committee to Nuke Elysium

To get used to the dizzying feeling of weightlessness, astronauts spend a considerable chunk of time in water. The initial test is to swim three lengths of a 25-metre pool without stopping. That might sound easy, but candidates must then do it again, and also tread water for 10 minutes… in a spacesuit. As if that’s not enough, each astronaut has to undergo a military water survival training course and become fully scuba qualified to start getting used to the exciting – but risky – sensation of being in space.

Wannabe astronauts get a more authentic taste of weightlessness as passengers in the so-called Vomit Comet – a converted C-9 jet aircraft that performs parabolic manoeuvres to produce periods of weightlessness that last about 20 seconds. Though that might seem fun as a one-off – even Stephen Hawking volunteered for it – prepare to feel queasy: the process is repeated up to 40 times in a day for trainees.