'In 1995 I reported to NASA to train as an astronaut. Three years later, I flew aboard the Space Shuttle Columbia on its 25th flight (code-name STS-90 Neurolab): a 16-day, 6.3-million mile mission dedicated to understanding how the nervous system functions in space.
'As the crew medical officer, I was one of the scifiles on board performing experiments on myself and the six other crew members. I was also one of the engineers, sitting on the flight deck during the lift-off phase.
'It took just eight and a half minutes to get into space. But the real thrill of being in space begins when you look out of the window; orbiting 150 miles above the Earth, once every 90 minutes; experiencing a sunrise or sunset every 45 minutes while listening to Louis Armstrong.
'My career background is emergency medicine, and in 1992 I was lucky enough to be selected to join the Canadian Space Agency. Now I'm based at the Johnson Space Center in Houston, directing research into programs to safeguard astronauts' health in space - and back on Earth.'
So you want to be a scientist?
'My advice is: Preparing to be a scientist is a lifelong activity.
'Being a scientist is about curiosity, wondering how things work. I was an average student all the way through school. So have the courage and conviction to pursue your dreams. Impossible is no longer a word that I use.
'Anything is possible.'
'We go to school to learn to be scifiles, and then go back to class to study to be astronauts.
'Mission specialist astronauts with specific jobs to do are trained to perform space walks, operate the robotic systems and work all the onboard shuttle systems. Training to fly in space is demanding, but it's like learning any other subject. And NASA is a school.
'Lectures teach about life on board the space shuttle and practical sessions deal with the technicalities of operating equipment in a weightless environment or working in space suits. We spend a lot of time in simulators. As a result, back on earth, you become aware how heavy your body is, constantly pulled down by gravity.
'Ongoing research at the Johnson Space Center is investigating how to protect astronauts from the hazards of the space environment, including microgravity and space radiation; how to maintain their medical, physical and psychological well-being before, during and after space flights, and how to prepare people for space missions of months rather than days.'
Under the microscope
What's the best thing about space travel?
'Appreciating the complexity of our planet's ecosystem, seeing the changes which we're making to the Earth.'
'I now find aeroplane travel tediously slow!'
'The funny thing is that the stars don't look any closer out in space.'
Spaceflight has information on how to become an astronaut, including how to do it if you're not a US citizen
The National Space Biomedical Research Institute seeks solutions to health concerns facing astronauts on long missions
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