Image caption Chris Hadfield became the first Canadian to walk in space during his 2001 shuttle mission

Astronaut Chris Hadfield already has a number of firsts to his name.

He was the first Canadian to undertake a spacewalk; and he was the first and only Canadian to board the Russian Mir space station.

He was also the first Canadian to operate his country's major contribution to the space shuttle - its robotic arm, or "Canadarm".

Now, he is about to become the first Canadian to command the International Space Stations (ISS).

"I'm being asked to command the world's spaceship; it's a big responsibility," Hadfield said.

"The leading nations of the world have built a laboratory with no gravity, at huge cost and toil. I'm only one of many commanders in a sequence; I recognise my relative importance. But it doesn't decrease the level of responsibility for the time that I'm the commander.

"So, my number one job of course is to maintain the health of the crew. We need to keep the people healthy and alive and productive onboard. Number two is the health of the spaceship, to keep the space station productive and functioning."

The former Royal Canadian Air Force colonel has been talking about his upcoming mission here at the annual meeting of the American Association for the Advancement of Science (AAAS).

Media playback is unsupported on your device Media caption Chris Hadfield: We need to take progressive steps away from Earth

To date, only one national outside of the US and Russia has been given the status of commander on the ISS, and that was a European Space Agency (Esa) astronaut, the Belgian Frank De Winne, who took the helm of the orbiting outpost in 2009.

Hadfield's big moment will begin when he launches to the station on a Soyuz rocket at the end of this year.

For three months, the 52-year-old will serve as a flight engineer in the Expedition 34 crew. Then, in March 2013, he will assume command of Expedition 35 for three months, before returning to Earth in his Soyuz capsule.

"We run about 100 experiments [on the ISS] consistently, rotating them all the time but there are about 100 experiments up there.

"So, the job of the commander is to build a group of people, both the astronaut crew and the ground crew that supports us, that can successfully execute the six months I'm up there - the three months that I'm the commander - to get those primary objectives done. Crew health and safety, vehicle health and safety, and then all the science and engineering and experimentation that comes with it."

It will be Chris Hadfield's third trip into orbit. His first was a little more than 16 years ago when he flew on space shuttle Atlantis to the Mir space station.

The Sarnia, Ontario-born astronaut then made his only other flight in 2001, when, as part of the shuttle Endeavour crew, he delivered Canadarm2 to the space station. Canadarm2 is a bigger, more sophisticated version of the robotic arm fitted in the shuttles.

It was during this mission that Hadfield undertook the first ever Canadian spacewalks.

Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter