With a round of hugs and handshakes, Canadian astronaut Bob Thirsk was welcomed aboard the International Space Station Friday after a two-day voyage on a Russian Soyuz spacecraft.

Thirsk, along with Russian astronaut Roman Romanenko and Belgian astronaut Frank De Winne, docked with the ISS at 8:34 a.m. ET.

The 55-year-old will be spending the next six months on the ISS, the longest period a Canadian has ever spent in space.

At a post-docking news conference of the new and existing crew members Thirsk was beaming, calling it an historic and happy day.

"You can't image the state of elation that the six of us have right now," Thirsk said. "We've got an incredible potential for success here. This is going to be something incredible. You ain't seen nothing yet. Thank you Canada. "

From the Russian control centre near Moscow, former astronaut and Canadian Space Agency President Steve MacLean congratulated Thirsk.

"It's wonderful to see all six of you up there, all five space partners working together, it's a historic day. All Canadian will be watching, especially you Bob, for the next 180 days," MacLean said.

Then it time for a quick phone call from Thisk's 81-year old mother, Eva.

"It looks great to see you there with all your friends, have a wonderful time and God bless," she said.

"Thanks Mom," was Thirk's response from 350 kilometres up in space.

Thirsk blasted off from the Baikonur cosmodrome in Kazakhstan on Wednesday.

It was the first time a Canadian has travelled aboard a Russian spacecraft. In the past Canadians have hitched rides aboard American space shuttles.

With the arrival, the crew on the ISS grows to six -- the largest-ever on the space station.

During his time on the station, Thirsk will be taking medication given to people with osteoporosis so researchers can examine its impact on minimizing bone loss.

Researchers will also be watching to see how he deals with the psychological effects of isolation and confinement and the longer exposure to ionizing radiation.

The research will help scientists plan for future missions, including to the moon and hopefully to Mars.

Next month, fellow Canadian astronaut Julie Payette is scheduled to visit Thirsk as part of a 16-day mission aboard the space shuttle Endeavour.

It will mark the first time ever two Canadian astronauts have been in space together.

In September, a Japanese cargo vehicle is scheduled to rendezvous with the station and Thirsk will have to use the Canadarm 2 to connect it to the ISS.

Thirsk will also complete an experiment where he'll control a roving robot at the CSA headquarters in Montreal from the ISS.

Prior to this mission, Thirsk's last flight was a 17-day flight aboard Columbia in 1996.