Canadian astronaut Robert Thirsk says that while an astronaut's greatest fear is injury or death, he is most worried about making a mistake during his six-month mission aboard the International Space Station.

Thirsk arrived at the station Friday aboard a Russian Soyuz spacecraft along with Russian astronaut Roman Romanenko and Belgian Frank De Winne. They joined astronauts Koichi Wakata and Mike Barret, and crew chief Gennady Padalka.

During a news conference Monday morning from the station, Thirsk, 55, said his greatest challenge was to learn to work quickly and efficiently to complete the multitude of repairs and experiments.

"I think for the newer members of this six-person crew, it's a little bit like herding cats for Gennady, trying to get us all organized and getting us all to accomplish our tasks in a day. The learning curve is steep," Thirsk said when responding to questions from Canadian reporters.

"Astronauts always have fear of injury or death, but our greatest fear is of making a mistake," Thirsk added. "So I just hope I can get through this six months without making any serious mistakes."

Among other tasks, Thirsk will take medication given to people with osteoporosis so researchers can examine whether it will help astronauts minimize bone loss.

As well, he will be tested for the psychological effects of isolation and confinement and will be monitored for exposure to ionizing radiation.

In relaying the day's schedule, Thirsk said the crew awakes at 6 a.m., eats breakfast and then reviews the day's messages from the four mission control centres around the world.

They get to work shortly after 8 a.m., break for lunch, then continue working until it's time to work out, which they do for a couple of hours every day, Thirsk said.

Before going to bed, the team will communicate with friends and family via email or an IP phone.

Thirsk said that because astronaut training centres contain fairly accurate replicas of the space station, it looks much as he expected.

Except he was surprised by how much stowage here is onboard, and that everything appears to be contained in Ziploc bags.

"This is a surreal world here," Thirsk said. "I sometimes feel like I'm in the middle of a Salvador Dali painting here."

The native of New Westminster, B.C. said he's brought a little bit of Canadiana with him to help with homesickness, including a copy of "Anne of Green Gables" and a signed photo of one of his heroes, hockey legend Jean Beliveau.

"I think he's a class act," Thirsk said of the former Montreal Canadiens star. "He's a role model for me. If I'm going to stay calm and collected on this expedition he's a good example for me to follow."

The arrival of Thirsk and his colleagues put six astronauts aboard the station for the first time in its history.

While the crew said there is plenty of room for them to comfortably work and eat their meals, it may be a different story later this month when seven more crew members arrive.

Among them will be Canadian astronaut Julie Payette, who will take off June 13 on board the space shuttle Endeavour for a 16-day mission.

With files from The Canadian Press