International Space Station: Astronauts celebrate 15 years living in space

Humans have been living on the International Space Station for 15 years straight as of today.

Since the first permanent crew moved in on Nov. 2, 2000, 220 people have come and gone, representing 17 countries. They included Canadian astronauts Julie Payette, Bob Thirsk, and Chris Hadfield, who served as space station commander in 2013.

Several Canadian astronauts and the Canadian-made robot arms Canadarm and Canadarm2 were also instrumental in building the space station, which has grown from three to 13 rooms in the past 15 years, Hadfield told CBC News in an interview.

"When they first moved in, it was sort of like that little temporary bunkie that you build next to the house that you plan to move into," he added. "Those first three guys had a pretty spartan existence. Now there are six guys up there, they're running hundreds of experiments."

Hadfield recalled that during his own stay, there were unique reminders of where he was.

"If you wait a little bit in your bedroom at night, you can hear the ricochets of the meteorites."

Hadfield said astronauts' work on the space station has produced inventions like a portable blood analysis machine that is used in remote locations in Canada today and a brain surgery robot based on Canadarm technology.

It's also helping researchers understand medical conditions such as osteoporosis, which astronauts are prone to in the microgravity conditions on the space station.

The fact that the space station orbits the Earth 16 times a day has also been an opportunity, Hadfield added.

"We get an accurate full understanding of the health of our world … like we've never been able to do in history before."

NASA and its global partners are celebrating the milestone, as are the six men aboard the space station. The U.S., Russian and Japanese crew plans a special dinner. NASA says more than 26,500 meals have been dished up on the space station in the past 15 years.

Commander Scott Kelly, who's on a yearlong mission, said the biggest benefit of the orbiting lab is furthering long-term exploration goals. He and his crewmates consider the space station a bridge or test bed for the technology needed to travel to Mars.

In a statement, NASA administrator Charles Bolden said astronauts on the space station "have been working off-the-Earth for the benefit of Earth, advancing scientific knowledge, demonstrating new technologies, and making research breakthroughs that will enable long-duration human and robotic exploration into deep space."

John Holdren, director of the White House Office of Science and Technology Policy, said "the international partnership that built and maintains the Station is a shining example, moreover, of what humanity can accomplish when we work together in peace."