The Soyuz docked on schedule with the station at about 8:34 a.m. ET. The Russian spacecraft had launched from the Baikonur Cosmodrome in Kazakhstan at about 4:34 p.m. local time on Wednesday.
Thirsk, Russian cosmonaut Roman Romanenko and Belgium's Frank De Winne will join the station's current crew, doubling the station's complement to six crew members for the first time in its history.
Russian Gennady Padalka, U.S. astronaut Michael Barratt and Japan's Koichi Wakata are already at the space station. In addition to performing scientific experiments on the space station, the 55-year-old Thirsk will serve as the crew's medical officer and robotics specialist.
It is the second mission in space for the British Columbian, who was born in New Westminster. He made his first 16-day space flight aboard the U.S. space shuttle Columbia in 1996.
Thirsk is the first Canadian to go to space aboard a Russian spacecraft. Canadian astronauts usually blast through the atmosphere via American space shuttles.
But it's a mode of transportation likely to be more common in the future, as the United States is planning to retire the space shuttle fleet in 2010.
Also on Friday, the Russian Space Agency said it has signed a $306 million US deal with NASA to ferry American astronauts to the space station in 2012, covering four planned launches aboard the three-person Soyuz.
Canadian astronaut Julie Payette is scheduled to join Thirsk aboard the station in June, as she is part of a seven-person crew set to blast off from Earth on the space shuttle Endeavour on June 13.
It will be the first time two Canadians will be in space at the same time. Payette and the Endeavour team, however, will only be staying a short time, as their mission is scheduled to last just 16 days."