Dr Thirsk became obsessed with space travel in his early school years after a teacher put on a broadcast of an American astronaut mission into space.
“Many years later, after I’d had some engineering and medical training, I was in a doctors’ lounge relaxing and I saw a newspaper with a huge ad in it saying Canada was ready to start an astronaut program, and this grade three dream came back to me,” Dr Thirsk said.
“I applied and I was very, very fortunate to finally be accepted.”
After years of medical preparation, anti-gravity training, and Russian language lessons — handy for work on the International Space Station — Dr Thirsk launched into space.
At 204 days, he still holds the Canadian record for the most time spent in space.
Evidently, Dr Thirsk is familiar with the health challenges associated with space travel.
While he said many of the effects of weightlessness on the human body — such as loss of muscle mass and bone calcium content — were reversible, he still had concerns of the effects of space travel on health.
“Things that are not reversible are things that are due to radiation,” Dr Thirsk said.
“I am concerned in the future about potentially developing cataracts or developing leukaemia or thyroid cancer.”
Image credit: NASA