Rebecca Morelle

John Mcfall is The European Space Agency 's first ever para-astronaut, selected to study how feasible it is for someone with a physical disability To Live and work In Space . Bbc News joined him on board a parabolic flight, where he experienced weightlessness for The First Time .

One minute John Mcfall is lying on The floor of a plane. The Next , he starts to float upwards, still horizontal, seemingly levitating towards The Ceiling .

He looks astonished - everyone on this far-from-normal flight does, as they slowly rise into The air. The sensation of being weightless, no longer pinned down by gravity, is extraordinary.

You feel totally out of Control - because you are. Any tiny movement against something solid sends you catapulting around The Cabin , bouncing into walls and people. It's like being in a slow-motion pinball machine.

A smile begins to form across John's face - he starts laughing. " It's brilliant, it's amazing, " he says.

Then suddenly, The weightlessness is gone and he falls to The ground.

John is an astronaut candidate with a Difference - he's an amputee. When he was 19 he lost his leg in a motorcycle accident, and now uses a high-tech prosthesis.

He has now been recruited by The European Space Agency (Esa) to take part in a ground-breaking study assessing How To make spaceflight accessible to people with physical disabilities.

" I saw that The European Space Agency had announced that they were looking for an astronaut with a physical disability, " he says, " and I looked at The person specification and thought, 'Wow, that's me - I would love to give that a go'. "

John's used to pushing himself to The Limit . After losing his leg and learning to walk again with a prosthesis, he took up Running - For Fun at first, then competitively. He went on to win a bronze medal in The 100m final at The 2008 Beijing Paralympics.

He then decided to become a doctor and is currently working as a trauma and orthopaedic registrar in Hampshire, But he's had to pause his medical Career - The opportunity to work with Esa was too good to turn down.

" 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. "

I've joined John on board a specially adapted aircraft to take a parabolic flight. As The plane flies steeply upwards, we experience extra gravity - About twice as much as usual - where your whole body is pressed down into The floor.

Then, as The plane gets ready to nosedive back down, there's a moment when we become weightless for About 20 seconds. It's not that gravity has vanished, we're still bound by The laws of physics. Instead, we're actually in Freefall - As Is The plane around us - But this reproduces zero-gravity conditions. The plane repeats this manoeuvre again and again.

There's a reason parabolic flights are nicknamed " vomit comets" - it's like riding on a mid-air rollercoaster.

Thankfully, I don't feel sick, But it's safe to say I'm not a natural astronaut.

I tumble, out of Control , squealing, asking for help to come down. But I end up pinned to The Ceiling - until The period of zero-gravity comes to an end, and I crash down like a sack of potatoes. Luckily The floor of this plane is Well padded.

Meanwhile, John is faring much better, soaring around and gaining confidence with every period of " zero-gravity".

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. "

John thinks that his prosthesis may be too high-tech for this environment, and a simpler one might fare better. And this is The whole point of his project with Esa: working out exactly what needs to be adapted for a person with a physical disability to spend time In Space . It will cover everything, from pre-mission training, to looking at whether a spacecraft would have to be modified to accommodate John's needs.

But he says Everyday Life in a microgravity environment is still The biggest unknown.

" Will I wear a prosthesis? And if I wear a prosthesis, will I have to have something that will accommodate variations in volume in my stump? Would I be able to run on a treadmill In Space ? Will we have to adapt a spacesuit for a spacewalk? If so, in what ways? " he wonders. " All these questions are things we do not have answers for. "

John is acutely aware that his disability is specific to him, and he needs to Take That into account while he's undertaking The study.

" I haven't got a Spinal Cord injury, I haven't got cerebral palsy, or spina bifida. So I'm thinking About how this applies to other disabilities as Well - But we have to start somewhere. "

There's a wider impact too. John hopes The Project will redefine people's expectations of what someone with a physical disability can do.

As The Flight nears its end, John keeps working on and improving his zero-gravity skills. He's now moving About easily and can even land Standing Up , while I continue to thwack down to The floor, every time.

When this project comes to an end, John isn't guaranteed a mission to space, But as The plane starts its preparations for landing, I ask if this experience has whet his appetite For Space , or made him have Second Thoughts About his new job.

" It's given me even more hunger and excitement, " he says with a huge grin. " It's just Awesome - I can't wait. "

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Source of news: bbc.com