John McFallhas become European Space Agency (ESA)'s first ever para-astronaut, who has been recruited to take part in a ground-breaking study to access how feasible it is for someone with a physical disability to live and work in space.
John's life changed overnight when a bike accident in the autumn of 2000, left him without his right leg. But he refused to give up and began pushing himself to the limit.
He learned to walk again with a prosthesis, gradually taking up running for fun initially and later, competitively. He went on to win a bronze medal in the 100m at the 2008 Beijing Paralympics.
John then decided to become a doctor and is currently working as a trauma and orthopedic registrar in Hampshire.
Then came the ‘out of the world’ opportunity to work with ESA.
"I saw that the European Space Agency had announced that they were looking for an astronaut with a physical disability," John says, "and I looked at the person specification and thought, 'Wow, that's me - I would love to give that a go'."
"I'm very much following my heart and I'm following my curiosity," he explains, "and I'm following my passion for science and life."
The para-astronaut experienced his first zero gravity parabolic flight test on Thursday as he took his first 'vomit comet' to space. Parabolic flights are nicknamed "vomit comets" for a reason- it's like riding on a mid-air rollercoaster.
The prosthesis John wears is technologically very complex, incorporating a microprocessor, hydraulics, a gyroscope, accelerometers and other force sensors.
"All those things together make the knee know where it is in space and how fast it's bending or straightening," John says.
He's assessing how well his prosthetic leg is operating in this unusual environment, and the challenge comes when weightlessness kicks in.
"You'll probably see I'm floating around with my leg out straight, because that gravity isn't there," he explains. "So it's harder for me to turn quickly - because my leg doesn't want to bend. I'm just getting used to that and working out how I can move myself in zero-g, but each parabola is a learning opportunity."