Chris Hadfield holds the distinction of being the first Canadian astronaut to walk in space.
He has since written three books, made television programmes, spoken at schools and taught at university, and his knowledge is much in demand.
"I think the things that I've done are still pretty rare in the human experience," he told Matt in our Friday profile interview.
"Once you have had an experience like commanding a space ship or seeing the world thousands of times, what do you do with that experience? Do you just keep it to yourself or try and find a way to let other people get it and roll it into their own decision making?"
Chris described NASA's main aim as "to use the high ground of space to better understand our own planet and find out what we're doing right and what we're doing wrong."
Listen to the full interview below:
